In 1983, University of Arizona Tree Ring researchers warned:

Our results show that the projected climatic change would have serious overall effects on the west. The number of sub-regions that are expected to have water shortages by the year 2000 would essentially double. The regions drained by the Colorado River and the Rio Grande would be especially hard hit as there is presently little, if any, unallocated water in these basins. Allocation changes required to meet a diminishing water supply would be extremely difficult in these basins due to the complex web of international treaties, interstate compacts and both federal and local laws.^[1]

About 42% of Arizona's water use comes from groundwater, 36% from the Colorado River, 18% from in-state rivers, including the Salt and Verde and 4% from high-quality treated wastewater called effluent.^[3]

Water resources have been managed primarily by the Salt River Project (SRP), the Central Arizona Project (CAP) and water utilities in the Phoenix and Tucson metropolitan areas. Their geographic domains, business structures and relationships with Arizona's Tribes have been shaped by more than 150 years of evolving federal and state laws and regulations.

Sources:

Water Geology

The canyon's average depth is 4,000 feet deep. It is 6,000 feet deep at its deepest point and 18 miles at its widest.^[1]

The canyon's uppermost layer is Kaibab limestone,hard sedimentary rock, composed mainly of calcium carbonate or dolomite, used as building material and in the making of cement which was formed at the bottom of the ocean. It now sits at the top of the Colorado Plateau, more than 9,000 feet above sea level.^[2]

Plate tectonicsa theory that explains the movement of Earth's lithospheric plates over its mantle lifted the Colorado Plateau between 70 and 30 million years ago. The river exposed spectacular layers of sedimentary rock, deposited by water. The oldest canyon rocks have been dated at 1.8 billion years.^[2]

The two current hypotheses explaining the uplift are shallow-angle subductionoccurs at convergent tectonic plate boundaries where a denser plate moves under a less dense plate or uplift caused by isostasy.state of gravitational equilibrium between Earth's crust and mantle, the crust floats at an elevation that depends on its thickness and density^[2]

Antelope Canyon, east of Page, is a small slot canyon,a long, narrow canyon channel with vertical sedimentary rock walls that formed after thousands of years of desert weather extremes. Its red color is due to the iron oxides that mixed with the sand that formed the canyon walls 191 to 174 million years ago.^[3]

The canyon is divided into two sections. Located at an elevation of 4,000 feet, Upper Antelope Canyon is the most famous, and is also known as "The Crack." The Navajo name for Upper Antelope Canyon, which is about 100 yards long and 120 feet deep, is Tsé bighánílíní, which means "the place where water runs through rocks." The canyon floor is usually dry and flat, but wet during monsoon season.^[3]

Lower Antelope Canyon is about 4.5 miles northwest of Upper Antelope Canyon. It is a little more than a mile in length, and narrower than the Upper Canyon along the canyon floor. The Navajo name for Lower Antelope Canyon is Hasdestwazi, meaning "spiral rock arches." It is also called "The Corkscrew."^[3]

Upper and Lower Antelope Canyon are a part of a system of several streams that flow into Lake Powell.^[3]

The 84,000 acres of Canyon de Chelly National Monument in the northeastern corner of the state, is located on the Navajo Nation in Chinle. About 40 families live within the park boundary which is managed by the National Park Service and the Navajo Nation.^[4]

Like the Grand Canyon, Canyon de Chelly was formed by running water. The Tsaile and Whiskey Creeks joined to form the Chinle Wash, which carved through de Chelly sandstone deposited during the Permian Period, 230 to 205 million years ago. In some places, the canyon is 800 feet deep.^[5]

The canyon provided protection to ancient Puebloans, who inhabited the canyon until the 1300s. The Hopi later migrated to the area, which was later settled by the Navajo.^[5]

Tonto Natural Bridge, about 10 miles north of Payson, is considered the largest natural travertinea white, tan, cream, rust-colored fibrous or concentric limestone mineral deposited by mineral hot springs bridge in the world. It is 183 feet high over a 400-foot long tunnel that is 150 feet across at its widest point.^[6]

Pine Creek, where the bridge is located, was formed by a rhyolitean extrusive igneous rock with a very high silica content, usually pink or gray in color with grains so small that they are difficult to observe without a hand lens, made up of quartz, plagioclase, and sanidine, with minor amounts of hornblende and biotite lava. The rock eroded, leaving purple quartz sandstone, which was lithified,transform from sediment into stone tilted, faulted and eroded.^[6]

The area was covered by seawater, leaving sand and mud comprised of limestone sediments. More volcanic eruptions covered the sediment with lava, forming a basalta dark, fine-grained volcanic rock that sometimes displays a columnar structure, typically composed largely of plagioclase with pyroxene and olivine cap which eroded and was shifted, creating the canyon.^[6]

About 5,000 years ago, precipitation began seeping underground through rock fractures, creating limestone aquifers and springs which carried dissolved limestone and calcium carbonatea white insoluble solid occurring naturally as chalk, limestone, marble and calcite, forming mollusk shells and stony corals creating a travertinea white, tan, cream or rust-colored fibrous or concentric limestone mineral deposited by mineral hot springs dam. The dam was eroded from below creating the bridge.^[6]

Kartchner Caverns is another spectacular geologic wonder. Located in southern Arizona, the cave was discovered in 1974 by Gary Tenen and Randy Tufts, who were exploring the limestone hills at the eastern base of the Whetstone Mountains. Unprotected caves can be seriously damaged, so Tenen and Tufts thought about developing the cave themselves. They kept the cave secret until February 1978 when they told property owners James and Lois Kartchner about their discovery.^[6]

Arizona State Parks finally purchased Kartchner on September 16, 1988, after 10 years of research, planning, construction, and legal issues which cost more than $28 million. The Conservation Celebration of Kartchner Caverns State Park was held on November 5, 1999. The lower caverns opened to the public on November 11, 2003.^[7]

The cave's formation began with a shallow inland sea that covered the area 330 million years ago. The sea deposited sediment layers and fossils that hardened into Escabrosa limestone. Over the last 10 to 15 million years, the limestone uplifted, forming the Whetstone Mountains.^[8]

A block of the limestone dropped down a fault thousands of feet below the mountains. Acidic rainwater penetrated the limestone block, creating the cave rooms and passages. Over thousands of years, dripping water formed speleothems.a mineral deposit formed in a cave^[8]

Sources:

Water History

Agriculture in the Salt River Valley began over 2,000 years ago with the Hohokam, who lived in the valley until about 1450. They constructed a sophisticated canal system that watered tens of thousands of acres of valley farmland.^[1]

Settlers arrived in the Salt River Valley during the 1860s when a U.S. Army outpost was established in 1865 at Camp McDowell, near the intersection of the Salt and Verde Rivers. Soldiers built canals from the Verde River and planted crops.^[1]

In 1867 settlers from Wickenburg led by Jack Swilling came to the valley and dug a ditch adjacent to a prehistoric Hohokam canal. One end of that ditch is now buried beneath north runway of Phoenix Sky Harbor International Airport.^[1]

The city of Phoenix, named in honor of the departed Hohokam community, was formed in 1870, when those living along Swilling's Ditch formed the Salt River Town Association, establishing their new town along a half-square-mile area between what is now Seventh Street and Seventh Avenue, south of Van Buren Street. They called the new town Phoenix. Swilling's Ditch was later named the Salt River Valley Canal.^[1]

Over the next decade, several canal companies combined, but water rights became contentious. The Arizona territory applied the "doctrine of appropriation," which recognized "beneficial use." Anyone could divert water from a river or stream with a few provisions:

• the first person to take a given amount of water and use it beneficially acquired a permanent first right to take that amount of water from the river
• the next water diverter could take water only after the prior user's water demand had been satisfied
• later water users had lower priorities
• water rights remained with the land, and were not transferrable to the land on which the water was used.^[1]

In 1863, Judge William Howell drafted the 400-page legal code for the entire Arizona Territory. The Howell Code included water rights provisions, establishing the state's surface water as public property. His system ensured that during a drought, some farm land was guaranteed to get sufficient water to maintain food crops. Control was no longer strictly in the hands of canal companies.^[1]

A seven-year drought, which began in 1891, was the result of low snowfall in northern valleys that supplied water to the Salt and Verde Rivers.^[1]

Wormser v. Salt River Valley Canal et al. (1892) became a landmark in Arizona water rights law. Judge Joseph Kibbey held that water rights belonged with the land, and could not be transferred, sold, or rented for use at other locations.^[1]

On August 17, 1898 President William McKinley signed Proclamation No. 19, creating the Apache-Sitgreaves National Forest in the northeastern Arizona Territory. It was followed by the Tonto National Forest, created on October 3, 1905.^[1]

The 1894 Carey Act granted millions of acres to the states and territories to finance irrigation so that local governments and private partnerships would construct storage dams and create irrigation districts,a special political taxing district established for agricultural improvement or irrigation and conservation purposes but the act failed to launch substantial irrigation projects because the states, territories and investors could not meet financial obligations.^[1]

By the depression of the mid-1890s investors were apprehensive about funding water projects and political conversations resulted in the 1902 National Reclamation Act, providing government funding for reclamation projects. Users would reimburse the federal government once they took over the completed projects.^[1]

The Salt River Valley Water Users Association (SRVWUA), formed in 1903 by commercial and local farmers, small ranchers and businesses and wealthy businessmen, filed its articles with the Maricopa County recorder on February 7, 1903 and two days later with the Secretary of the Arizona Territory.

SRVWUA enabled residents to use their land as collateral for the federal funds to construct Roosevelt Dam. Because the association represented a broad constituency it united water users in the Phoenix area and reduced litigation and competition for water resources. Area landowners could join SRVWUA for a fee of ten cents per acre.^[1]

In 1904 SRVWUA initiated Patrick T. Hurley v. Charles F. Abbott et al., 259 F. Supp. 669 (D. Ariz. 1966), to clarify water rights. The federal government joined the suit as a cross-complainant on behalf of the Indians of the Salt River and Fort McDowell Reservations.^[1]

By 1908 2,000 people were living in the town of Roosevelt.^[1]

In March 1910, Judge Edward Kent issued his Hurley opinion, which defined the three classes of valley water:

• Class A lands were those that had been continuously cultivated since first irrigated
• Class B lands had been irrigated in the past but not after 1903, they had low-priority rights and had been left without water during the drought of 1897-1904
• Class C lands were those with no history of irrigation.^[1]

Kent also determined water allocations to the Salt River and Fort McDowell Reservations and gave them the highest priority.^[1]

The Roosevelt Dam was dedicated in 1911. By 1915 Roosevelt Lake had filled with snow runoff even though 1,000 acre-feet of water per day was being released for irrigation. In 1917 the federal government transferred operation of the Salt River Project (SRP) to SRVWUA, which sent the first reimbursement payment of $132,000 to the federal government in December.^[1]

Sources:

 
Colorado River Basin^[*]

The Colorado River is about 1,450 miles long. The headwaters of the Colorado River are located in Rocky Mountain National Park near Grand Lake, Colorado.^[17] It is about 1,450 miles long and flows across the international border into Mexico. The drainage basin area is about 246,000 square miles and includes all of Arizona and parts of California, Colorado, New Mexico, Nevada, Utah and Wyoming.^[1]

The river system supports $1.4 trillion of the annual U.S. economy and 16 million jobs, about 1/12 of U.S. domestic product. Without Colorado River water Arizona's gross state product would drop by more than $185 billion per year and the state would lose more than 2 million jobs.^[16]

For every 1C^o temperature rise Colorado River flow has decreased by 9.3%, a depletion of 1.5 billion tons of water lost to evaporation or lack of melting snowpack.^[16]

In addition to temperature changes dust may also control the speed at which spring snowmelt feeds the headwaters of the Colorado River. More dust correlated with faster spring runoff and higher peak flows because dust-covered snow is darker and absorbs more heat than white snow.^[18]

Windblown dust has increased in the Southwest due to climate change and human land-use. As rainfall decreases protective soil is removed exposing bare soil. Winter and spring winds pick up the dusty soil and drop it on the Rockies to the northeast at an annual rate of about five times higher than in the mid-1800s.^[18]

The major tributaries of the Colorado River, from northeast to southwest, include the Green, Dirty Devil, Escalante and San Juan Rivers. The Green River also has several major tributaries (from northeast to southwest) including the Uinta, White, Willow Creek, Price and San Rafael Rivers.^[2]

The Colorado River used to flow into a marsh in the Gulf of California.
Gulf of California
NASA
Nov. 30, 2003
Wikipedia Gulf of California
https://en.wikipedia.org/
wiki/Gulf_of_California#/media/
File:Gulf_of_California.jpg
public domain
Now it disappears in the farmlands at the base of the Sierra de Juarez Mountains
Sierra Juarez
Prsjl
Aug. 2, 2009
Wikipedia Sierra Juárez, Oaxaca
https://en.wikipedia.org/
wiki/Sierra_Ju%C3%A1rez,_Oaxaca#/
media/File:Yagila.JPG
CC BY-SA 3.0 in Mexico, until nothing remains. Only about 10 percent of all the water that flows into the Colorado River reaches Mexico, where it is used for farming.^[3]

Modern use of Colorado River water began in the late 1800s when water was diverted to California's Imperial Valley
The Imperial Valley from the highway between Tijuana and Mexicali
CharismaticDespot
Jun. 12. 2019
Wikipedia Imperial Valley
https://en.wikipedia.org/
wiki/Imperial_Valley,_California#/
media/File:ImperialValleyfromBC.jpg
CC BY-SA 4.0 for irrigation. Competition for Colorado River water has resulted in decades of political and legal confrontation and compromise.^[4]

The Colorado River is an important water resource for areas outside of the basin, including Denver, Salt Lake City, Albuquerque, Los Angeles and San Diego for municipal water, and the Imperial Valley in California for agricultural water. The river and its tributaries provide water to the nearly 30 million people, both within and outside of the basin and it irrigates nearly 4 million acres of agricultural lands.^[1]

In the early 1900s, Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming negotiated for shares of the Colorado River.

Current annual allotments in the Lower Basin were established in 1928 as part of the Boulder Canyon Project.^[6]

Arizona, Nevada and California comprise the Lower Basin and receive 2.8 million acre-feet, 300,000 acre-feet and 4.4 million acre-feet respectively. The 1944 U.S.-Mexico Water Treaty provides 1.5 million acre-feet of Colorado River water to be delivered to Mexico annually.^[5]

Current specific annual allotments in the Upper Basin were established by the Upper Colorado River Basin Compact of 1948.^[7]

Arizona's Colorado River water has a unique priority rights system:

• first: present perfected rights, described in Arizona v. California are the most senior
• second: federal reservations and perfected rights established before September 30, 1968
• third: water rights held by water users who executed contracts with the U.S. on or before September 30, 1968
• fourth: held by water users with contracts, secretarial reservations or other rights established with the U.S. after September 30, 1968 and CAP
• fifth: contracts for any unused Arizona entitlement water
• sixth: water users have contracts for any surplus apportionment of water^[11]

The Bureau of Reclamation plays a major role in the control and distribution of surface water within the Colorado River Basin through management of large federal water projects like Glen Canyon Dam and Lake Powell and Hoover Dam and Lake Mead.^[1]

More than 10% of the river's water is lost, due to reservoir evaporation and seepage. Upper Basin states are already charged for evaporation from federally-managed reservoirs, but Lower Bsin states are not, based on the Supreme Court Arizona v. California decision.^[12]

The new Lower Colorado River Basin System Conservation and Efficiency Program, funded by an initial allocation through the Inflation Reduction Act and managed through the Bureau of Reclamation, will help increase water conservation, improve water efficiency, and prevent system reservoirs from falling to critically low elevations that would threaten water deliveries and power production.^[13]

Hoover Dam is located in Black Canyon on the Colorado River at the Arizona-Nevada border. It was constructed between 1930 and 1936 and is the highest concrete arch dam in the U.S. It created Lake Mead, which extends for 115 miles (185 km) upstream and is one of the largest artificial lakes in the world. The dam is used for flood and silt control, hydroelectric power for 1.3 million,^[15] agricultural irrigation and domestic water supply.^[9]

Glen Canyon Dam is the second highest concrete-arch dam in the U.S. and created the 26.2 million acre-feet of water storage capacity in Lake Powell. The Glen Canyon power plant produces around 5 billion kilowatt-hours of hydroelectric power annually, distributed by the Western Area Power Administration to Wyoming, Utah, Colorado, New Mexico, Arizona, Nevada and Nebraska. Hydropower revenues help fund environmental programs associated with Glen and Grand canyons.^[10]

To the delight of many hikers, Lake Powell's low water level recently revealed long-hidden Cathedral in the Desert and the Gregory Natural Bridge. These formations were flooded when Glen Canyon Dam was completed.^[14]

On May 22, 2023 Arizona, California and Nevada agreed to take less water from the Colorado. In return the federal government will pay $1.2 billion to irrigation districts, cities and Tribes related to the cutbacks. The agreement will end in 2026. The reductions are about 13% of Lower Colorado Basin water use, about 3 million acre-feet of water over the next three-an-a-half years.^[19]

One acre-foot equates to a yearly supply for three Arizona families.^[5]

Sources:

Sonoran Desert

The desert covers 100,000 square miles of California, Arizona, Sonora, Mexico and Baja California.^[1] and is part of the Basin and Range province composed of long, low valleys bordered by parallel mountain ranges formed more than 40 million years ago by volcanic activity that also formed the Chiricahua, Superstition, Ajo, Kofa, Galiuro and Gila mountains.^[2]

About 12 million years ago the Basin and Range area expanded and stretched. Around 8 million years ago the expansion stopped and stabilized, leaving about 5,000 feet (1,525 m) of gravel, sand and clay in valleys that resulted in our current desert aquifers. About 6 million years ago California's San Andreas fault separated Baja California from the main part of the Sonoran Desert.^[2]

The desert's northeastern boundary is the mile-high escarpmentlong, steep slope, especially one at the edge of a plateau or separating areas of land at different heights called the Mogollon Rim
Mogollon Rim from east of Pine, Arizona
K. Dooley
Oct. 10, 2009
Wikipedia Mogollon Rim
https://en.wikipedia.org/wiki/
Mogollon_Rim#/media/File:
Mogollon_Rim_east_of_Pine.jpg
CC BY 2.0 of the Colorado Plateau.^[2] The desert's eastern edge in southeast Arizona is composed of high valleys and mountain ranges including the Pinaleno and Chricahua mountains. The southeast edge is at the Sierra Madre Occidental, 30 million year-old volcanic rocks in Mexico. In the west the desert is bordered by mountain ranges between 3,000 and 10,000 feet.^[2]

The desert contains three basaltic volcanic fields that formed in the last 4 million years. The most famous, the Pinacate in Sonora, Mexico, has a 4,000 foot stratovolcanoa volcano built up of alternate layers of lava and ash surrounded by hudreds of cinder conesa cone formed around a volcanic vent by fragments of lava thrown out during eruptions.^[2]

The oldest stratified rocks have been dated to about 1,200 million years ago. They contain algae and small mushrooms that survived despite Precambrian tides.^[2]

Paleozoic (570 to 240 mya) shales and limestones include trilobites,an extinct fossil arthropod recognized by its distinctive three-lobed and three-segmented form shark and fish teeth, crinoids,any of a large class of invertebrates that are echinoderms and usually have a cup-shaped body with five or more feathery arms coral, bryzoans,a non-moving aquatic invertebrate of the phylum Bryozoa which comprises of the moss animals conodonts,a fossil marine animal of the Cambrian to Triassic periods, having a long wormlike body, numerous small teeth and a pair of eyes, may be the earliest vertebrate clams, brachiopods,animal with a hard valve on its upper and lower surface oysters and cephalopods.an active predatory mollusk of the large class Cephalopoda such as an octopus or squid^[2]

Mesozoic (150 to 90 mya) fossils include lizard tracks, turtles, horsetails and petrified wood, formed when the land rose and water drained. Late Cretaceous rocks in the Santa Rita mountains include sauropods,a very large plant-eating quadruped dinosaur with a long neck and tail, small head and massive limbs horned and duckbilled dinosaurs and ancient mammals.^[2]

Cenozoic rocks include fossil ancestors of modern horses, titanotheresan extinct herbivorous hoofed mammal of the family Brontotheriidae of the Eocene and Oligocene epochs and oreodonts.an extinct, four-toed, ruminant, artiodactyl mammal of the Merycoidodontidae and Agriochoeridae families living in North America from the Eocene to the early Pliocene and resembling swine

Pleistocene fossils from the last two million years include camels, bison, modern horses, mastodons,any of various extinct mammals of the elephant family existing from the Miocene through the Pleistocene distinguished by molar teeth with cone-shaped cusps mammoths, giant ground sloths, wolves, lions, giant beavers and bears.^[2]

The Pleistocene climate was characterized by glaciers and world-wide climate changes. Arizona mountain glaciers existed above 9,000 feet (2,740 m), producing strong streams that transported rocks, soil and other debris from mountains and depositing it in canyons. The flowing water created alluvial fansa fan-shaped mass of deposited material atthe mouth of a river or stream that produced bajadas.a broad alluvial slope from the base of a mountain range into a basin formed by joined alluvial fans Below the bajadas are pedimentsa broad, gently sloping expanse of buried rock debris extending outward from the foot of a mountain slope, especially in a desert that prevented some valley alluvium and its water from flowing outward.^[2]

Thousands of years of weathering have created rounded boulders and hoodoosa column or pinnacle of weathered rock along Gates Pass Road west of Tucson in Saguaro National Park, in the Santa Catalina mountains north of the city along Mt. Lemmon Highway, in Texas Canyon along I-10 east of Benson and on Camelback Mountain in Phoenix.^[2]

The desert's extreme climate is characterized by sunny winters and a summer monsoon season. It is home to at least 60 species of mammals, more than 350 bird species, 20 amphibians, 100 reptiles, about 30 species of native fish, more than 2,000 species of plants^[3] and the only jaguars in the U.S. and the world's only saguaro cactus.^[1]

Sources:

Tribal Water

The court found that when the federal government created the Fort Belknap reservation
Fort Belknap reservation
AWMcphee
Jul. 24, 2019
Wikipedia Fort Belknap Indian Reservation
https://en.wikipedia.org/
wiki/Fort_Belknap_Indian_Reservation#/
media/File:1150R_Fort_Belknap_
Reservation_Locator_Map.svg
CC0 public domain it reserved the right to use a sufficient amount of the river's water to fulfill the purposes of the reservation as a homeland for the Gros Ventre and Assiniboine people.^[1]

The Winters Doctrine rights now apply to tribes in Arizona and across the country. These rights

• are considered as having been established as of the date the federal government created the reservation involved
• mean tribal rights are nearly always senior to those of most other current users of Western water
• cannot be forfeited by non-use, as can the rights held under state law according to the principle of prior appropriation
• scope is sometimes quantified as the amount of water needed to support practically irrigable acreage on a reservation, but the rights, once quantified, can be used for non-agricultural purposes
• involve the future reservation needs.^[1]

In 1979 a Supplemental Decree established "present perfected rights to the use of the mainstream water in each State and their priority dates," describing Tribal water rights and noting those rights "shall continue to be subject to appropriate adjustment by agreement or decree of this Court."^[4]

The Court referred the matters to a new special master who determined that the Secretary of the Interior's orders issued between 1969 and 1978 had determined the Tribes' reservation boundaries for purposes of the 1964 Decree. Those boundary lands determinations increased reservation land areas and entitled Tribes to additional water.^[4]

The special master also decided that there were additional lands in the 1964 boundaries entitled to water. In a 1983 ruling the Court rejected this recommendation, refusing to reopen the 1964 Decree to award the Tribes additional waters. The Court held that the Secretary's findings were not final determinations because the affected states had not had an opportunity to seek judicial review. The California water agencies challenged the Secretary's findings in federal district court.^[4]

After this ruling the states and agencies petitioned the Court to reopen its 1964 Decree, seeking a ruling on whether the Quechan, Fort Mojave and Colorado River Indian Reservations were entitled to additional boundary lands and whether the Tribes were entitled to additional water rights.^[4]

The Court appointed two new special masters who issued orders resulting in a report recommending the Court approve proposed settlements regarding the Fort Mojave and Colorado River Indian Reservations. The special masters' report did not favor additional water for the Quechan Tribe on the grounds that a judgment of the Court of Claims had divested the Tribe of any claim to the boundary lands and corresponding water rights.^[4]

In a 1989 ruling the Supreme Court approved the Fort Mojave and Colorado River Reservations settlement agreements. In 2000 the Court rejected the special master's recommendation that the Quechan Tribe was precluded from pursuing a claim.^[4]

After the 2000 ruling the parties made several attempts to settle the claims of the Quechan Tribe, resulting in agreements with Arizona, California and Colorado water districts that were approved by the Supreme Court in 2005. The settlements provided the Tribe with over 26,000 acre-feet of water per year.^[4]

Even though Tribes in the Colorado River basin are among the most senior water rights holders, the amount and access for the Havasupai, Hopi, Hualapai, Kaibab Band of Paiute Indians, Navajo Nation, Pasqua Yaqui, San Juan Southern Paiute, Tonto Apache and Yavapai-Apache Nation Tribes is unresolved.^[5]

The Colorado River borders more than 100 miles of Hualapai land in the Grand Canyon, but the Tribe can't access that water.^[6] H.R.7633 - Hualapai Tribe Water Rights Settlement Act of 2022, introduced in the U.S. House of Representatives by Arizona Rep. Tom O'Halleran in April, has not yet passed.^[7] Tribal members must fill water trucks from fire hydrants via a 30-mile round trip to Peach Springs outside of the Grand Canyon to obtain water.^[6]

The Hopi depend on corn, part of the basis of their creation story, in which their creator gave them a gourd of water, a planting stick and a short ear of blue corn. For generations they have depended on snowmelt to irrigate their gray, red and white corn fields between the First Mesa and Second Mesa reservation in northern Arizona. Now corn fields are affected by hotter weather, stronger winds and crop-eating animals like deer and elk that can no longer find food elsewhere.^[9]

Sixty miles to the west Hopi farmers use the Pasture Canyon reservoir, built by Mormon settlers in the late 19th century, to irrigate Moenkoepi fields via irriagtion ditches which supply water to corn and beans.^[9]

Because many Hopi ceremonies required corn Arizona's continuing drought has affected the Hopi way of life, but Tribes are now depending on irrigation and are planning new ways to provide water for their fields.^[9]

A bill signed by President Biden in January 2023 allows the Colorado River Indian Tribes (CRIT) to lease their 650,000 acre-foot water allocation.^[10]

In April 2023 the Gila River Indian Community (GRIC) announced that it will leave a substantial part of its Colorado River allotment in Lake Mead for the next three years. In return, the Biden administration will pay the Tribe about $150 million which will be used to restore wells and build water-related infrastructure on Tribal land. The federal government will fund a $83 million pipeline to deliver recycled wastewater to the reservation for farming.^[10]

On May 3, 2023 the EPA proposed federal baseline water quality standards for Indian reservations lacking CWA standards for half a million Tribal members. The goals are to protect 26,000 miles of rivers and streams, 1.9 million acres of lakes, reservoirs and other surface waters and aquatic life. If enacted the new regulations would introduce a common set of policies for Tribal waters.^[11]

Sources:

Most of Arizona lies within the Colorado River drainage basin.an area of land where precipitation collects and drains into a common outlet, such as a river, bay or other body of water

The Gila, Salt and Verde rivers began forming between 2 and 3 million years ago around the beginning of the Quarternary period. All three rivers began in basins that filled up and overflowed.^[5]

Dams and irrigation systems now prevent the water from these rivers from draining into the Mogollon Rim and nearby mountain ranges. Without retention this water would move down canyons and valleys and into the Gulf of California.^[5]

A Nature Conservancy study determined that 35% of Arizona's natural, perennialpresent all seasons of the year flowing rivers had been altered or have disappeared due to dams, diversions and groundwater pumping.^[4]

A Center for American Progress Disappearing Rivers analysis added climate change and development to the list of factors affecting Arizona's rivers. The report concluded that 48% of the state's rivers no longer flow freely because of obstructions, which include 373 dams, and 33% flow through lands significantly altered by human activity.^[6]

The report also recommended

• protecting Arizona's rivers with a state river protection system
• conserving and restoring river headwaters by directing funding to projects that protect and restore forest headwater resources
• expanding partnerships with federal and city agencies and drinking water utilities
• reevaluating dams and floodcontrol infrastructures through modernization and restoration processes
• collaborating with private landowners
• planning for continuing water scarcity by reducing demand and creating innovative streamwater protection solutions^[6]

In 1999 wildlife officials released 16 into the San Pedro Riparian National Conservation Area about 80 miles southeast of Tucson. According to the Watershed Management Group a recent survey demonstrated that a few dozen now live along the San Pedro River in both Arizona and Mexico. The beavers compete with wayward cattle that eat some of the same vegetation consumed by the beavers.^[7]

Beavers' dams expand wetlands that store carbon and create marshes that are less fire-prone than dry areas. But they sometimes annoy ranchers whose fields are flooded as a result of the beavers' activities. They are, however, a valuable part of the San Pedro environment.^[7]

Arizona's 10 Longest Rivers
river↕	length mile/km↕	information	related image
Colorado	1,450/2,330	drains an open, arid watershed in two Mexican and seven American states begins at La Poudre Pass in the Southern Rocky Mountains of Colorado, at 10,184 feet, 3,104 meters, above sea level rises from the Rocky Mountains flows through the Grand Canyon and Colorado Plateau before joining Lake Mead where turns towards the international border once in Mexico, it flows towards River Colorado Delta[1]	La Poudre Pass at the Continental Divide R. Deschner Aug. 17, 2000 Wikipedia La Poudre Pass https://en.wikipedia.org/ wiki/La_Poudre_Pass#/media/ File:Rock_Mountain_National _Park_North_Entrance_Sign.JPG CC BY-SA 3.0
Gila	650/1,050	main Colorado tributary source in Sierra County on the Continental Divide's slope flows through Gila National Forest drains 60,000 square miles arid watershed mainly in the U.S. extends to the north parts of Sonora dry near Yuma, about halfway through its 500-mile trip to the Colorado River was once navigable, from its mouth to Phoenix South of Phoenix, it crosses the Gila River Indian Reservation as an intermittent stream due to irrigation diversions[1],[2] likely began in the Safford Basin the San Carlos Indian Reservation[5]	A beaver dam in the Gila River M. Kowal Jun. 4, 2021 Wikipedia Gila National Forest https://en.wikipedia.org/ wiki/Gila_National_Forest#/media/ File:A_beaver_dam_spans_a_section_of _the_Middle_Fork_of_the_Gila_River.jpg CC BY-SA 4.0
Little Colorado	315/507	branch of Colorado River it and its main tributary, the Puerco, drain about 26,500 square miles of watershed in west New Mexico and eastern Arizona lower part of the river is the most extended arm of the Grand Canyon's longest arm which stretches for about 57.2 miles before joining Colorado River[1]	Puerco River Finetooth Sep. 26, 2010 Wikipedia Puerco River https://en.wikipedia.org/ wiki/Puerco_River#/media/ File:Puerco_River_in_ Petrified_Forest_NP.jpg CC BY-SA 3.0
Salt	200/320	longest branch of Gila drains an area of about 13,700 square miles its headwater tributaries, East Fork and Black River, stretch its length to 300 miles got its name because it flows through a large salt deposit after merging with the Black and White River in the White Mountains in Gila County[1] began in what is now known as Roosevelt Lake overflowed across surrounding mountains and into the East Valley, through the Superstition Mountains to south of Fountain Hills[5]	Gila Mountains D. G. De Vries Jan. 1, 2005 Wikipedia Gila Mountains (Yuma County) https://en.wikipedia.org/ wiki/Gila_Mountains_(Yuma_County)#/ media/File:Context_view,_looking_ downhill_from_afterbay_at_the_ east_rear_of_the_Pumping_ Plant_-_Wellton-Mohawk _Irrigation_System,_Pumping _Plant_No._2,_Bounded _by_Interstate_8_to_south, _Wellton,_HAER_AZ-68-B-2.tif public domain
Santa Cruz	184/296	with headwaters in San Rafael Valley it flows through northern Sonora, Mexico, and Southern Arizona, and past Santa Cruz to Sierra San Antonio, where it returns to the U.S. then flows northwards past Marana to Gila River and Santa Cruz flats, with the Santa Rita Mountains and San Cayetano on its east and the Sierrita Mountains and Atascosa on its west[1]	San Rafael Valley The Old Pueblo Oct. 4, 2014 Wikipedia San Rafael Valley https://en.wikipedia.org/ wiki/San_Rafael_Valley#/media/ File:San_Rafael_Valley_Arizona_2014.JPG CC BY-SA 4.0
Verde	170/270	major tributary of the Salt one of the most significant Arizona-based perennial streams with a mean flow rate of about 602 cubic feet per second rises from a dam in Lake Sullivan then flows for 125 miles through the state, private land, and the Tonto National Forest[1] originates from a series of springs 20 miles north of Prescott in the Big Chino Valley is one of only two Arizona watercourses to receive the Wild and Scenic River designation the other is Fossil Creek, which feeds into the Verde[5] Clover Springs project restored 2,800 feet of stream channel in the headwaters of West Clear Creek[8]	Verde River upstream of Clarkdale Finetooth Mar. 10, 2013 Wikipedia Verde River https://en.wikipedia.org/ wiki/Verde_River#/media/ File:Verde_River_near_ Clarkdale,_Arizona.jpg CC BY-SA 3.0
Puerco	167/269	flows in Northeastern Arizona and northwestern New Mexico through the Painted Desert one of the branches of Little Colorado drains a 2,654 square mile area has an average discharge rate is about 70 cubic feet per second dry most of the year overflows during downpours[1]	Painted Desert Joyradost Jan. 1, 2000 Wikipedia Painted Desert https://en.wikipedia.org/ wiki/Painted_Desert_(Arizona)#/ media/File:Painteddesert1.JPG public domain
Virgin	162/261	source on a Navajo Reservation in Utah flows in Arizona, Utah and Nevada was designated as the first scenic and wild river in Utah during Zion National Park's centennial celebrations was named by Jedediah Smith as Adams River in 1826, but map maker John Fremont changed its name[1]	Zion National Park seen from Angel's Landing Diliff Sep. 13, 2004 Wikipedia Zion National Park https://en.wikipedia.org/ wiki/Zion_National_Park#/media/ File:Zion_angels_landing_view.jpg CC BY-SA 3.0
San Francisco	159/256	leading branch of Upper Gila rises near Alpine and then extends to New Mexico before entering Arizona at Clifton drains into the Gila[1]	Alpine, Arizona NASA/Landsat 7 Mar. 21, 2010 Wikipedia Alpine https://en.wikipedia.org/ wiki/Alpine,_Arizona#/media/ File:AlpineAZ.jpg public domain
San Pedro	140/230	northern-flowing river rises from Cananea in Sonora, Mexico last free-flowing river in the southwestern parts of the country hosts more than 60% of the avian species in America, including 300 species of migrating birds and 100 breeding bird species[1]	Cananea, Sonora, Mexico in 1908 SMU Central University Libraries Jan. 14, 2011 Wikipedia Cananea https://en.wikipedia.org/ wiki/Cananea#/media/ File:Cananea,_Sonora,_ca_1908.jpg no restrictions

Sources:

Salt River Project

Starting in the 1920s and for the next 30 thirty years Salt River Valley Water Users' Association (SRVWUA) was the leading valley water supplier.^[1]

A 1920 study discovered that the water table was rising 1.5 feet per year. There were about 43,000 acres with a water level of about 10 feet below the surface. To capture that water 33 wells were dug to remove 200,000 acre-feet of groundwater per year. In locations where building wells was not practical ditches were dug to divert excess water.^[1]

The system was divided into 45 divisions under the supervision of water masters. In 1922, a group of Yaqui Indians from Mexico arrived to work on maintenance crews. SRVWUA provided them with permanent housing, and the crews remained into the 1950s.^[1]

There were several floods during the early 1920s, so Phoenix, Maricopa County and SRVWUA funded Cave Creek Dam which stopped a major flood in 1923.^[1]

In the early 1920s other groups on the periphery of the Salt River Project (SRP) attempted water irrigation programs. The Auxiliary Eastern Canal Landowners' Association (ECLA) wanted to buld a dam at Mormon Flat and irrigate 35,000 acres with a combination of floodwater and groundwater, but SRVWUA had a prior water claim to the Salt and Verde water that ECLA wanted.^[1]

The Verde River Irrigation and Power District (VRIPD) wanted to divert water that was being used by the SRP, but like ECLA, lacked funding and political support to build the proposed Verde Dam.^[1]

In 1930 groundwater had become scarce, with reservoir storage at close to 100,000 acre-feet. SRP turned to groundwater and installed 45 high-capacity pumping plants in less than a year.^[1]

SRVWUA then had a bonded debt of $11 million for three Salt River dams, and owed the federal government $4.8 million for the balance of the Roosevelt Dam costs. SRVWUA requested another $3.6 million from the federal government, agreeing to pay back all of its federal debts over the next 20 years.^[1]

During and after the Great Depression, SRVWUA managed to maintain its credit rating and managed to collect payments from water users.^[1]

In 1933 the Public Works Administration (PWA) provided the U.S. Bureau of Reclamation, which established an office in Phoenix, $19 million to finance the Verde project. But reports indicated that the project was ill-advised.^[1]

In 1936 the Maricopa County Board of Supervisors approved SRVWUA's request to form the Salt River Project Agricultural Improvement and Power District (SRPAIPD), separating the Salt River water and power management functions.^[1]

The Bartlett Dam was started in 1937 and completed in 1939, creating a 2,185 acre reservoir that stored 180,000 acre-feet of water. This dam was financed with federal funds and built by the Bureau of Reclamation, symbolizing the relationships between SRP and the federal government.^[1]

Phelps Dodge Corporation needed additional water for its Morenci mining operations on the Gila River in southeastern Arizona, In 1944 construction on the Horseshoe Dam, paid for by Phelps Dodge, began. It is the only earth and rockfill dam in the SRP system.^[1]

In 1947 21-year-old University of Arizona graduate, Louisa Simons, became SRP's first female engineer.^[1]

By the end of WW I, the Phoenix area economy was booming. In 1948 the percentage of SRP customers increased by 28.5% because of new housing subdivisions and new businesses.^[1]

The SRP dam system developed over several decades:^[2]

• Salt River dams➔
  • Theodore Roosevelt Dam, started in 1905 and completed in 1911, was later refurbished to a height of 357 feet. It provides enough water storage for the needs of a million people, and has hydrogeneration capacity of 36,000 kilowatts.^[3]
  • Horse Mesa Dam 27 was completed in 1927 and is 305 feet high and 660 feet long. It has three hydroelectric generating units that produce 32,000 kilowatts and one pumped storage hydroelectric unit added in 1972 that produces 97,000 kilowatts.^[4]

  

  • Mormon Flat Dam was built between 1923-25. It is 224 feet high and 380 feet long. The dam has two hydroelectric generating units. One is a conventional unit rated at 10,000 kilowatts and the other is a pumped storage unit built in 1971 rated at 50,000 kilowatts.^[5]
  • Stewart Mountain Dam was built between 1928 and 1930, and is 212 feet high and 583 feet long. A 13,000 kilowatt hydroelectric generating unit is operated at the dam during the summer.^[6]

• Verde River dams➔
  • Horseshoe Dam was built between 1944 and 1946 by the Phelps Dodge Corporation and the Defense Plant Corporation as part of a water exchange arrangement. The earthen dam is 144 feet tall and 1,500 feet long, including the spillway. It has no hydroelectric generating capabilities. The dam created a reservoir.^[7]
  • Bartlett Dam was built between 1936 and 1939. It is The multiple-arch dam is 308.5 feet high and 800 feet long. It has no hydroelectric generating power. This dam has a reservoir.^[8]
  • Granite Reef Diversion Dam construction began in October 1906 and was completed in May 1908. This little The dam is only 29 feet high and is 1,000 feet long. It does not generate power.^[9]

• East Clear Creek dams➔
• C.C. Cragin Dam project consists of a number of facilities, including electrical transmission line, and a generating plant. Most of the project is located in the Coconino and Tonto National Forests.^[10]

Urbanization created a new problem. Ditches and canals became traffic hazards and trash and weed collectors. By 1954 seven miles of canals and were lined with concrete and 28 miles of ditches were replaced with pipes at a cost of $40,000 per mile. They became separations for new roads and subdivisions.^[1]

In the 1960s, the metropolitan area needed new water resources, which then included treated wastewater released into the Salt River bed.^[1]

In February 1980 three heavy rainstorms put enormous pressure on the entire SRP dam system. Roads washed out and power houses were flooded. SRP released 180,000 cubic feet per second from the system, the largest controlled flow ever to go down the Salt River, to avoid reservoir flooding.^[1]

The Ninth Circuit Court of Appeals James et al. v. Ball et al., 613 F.2d 180 (1979) decision challenged the way that SRP allowed its membership to vote. In 1981 the U.S. Supreme Court overruled the Appeals Court and ruled in SRP's favor, and landowners who had more acreage had greater voting rights.^[1]

The 1988 Salt River Pima-Maricopa Indian Community Water Rights Settlement agreement provided the Tribe with financial support for water use planning and agricultural and industrial development. It also served as a model for future agreements with the Fort McDowell Indian Community in 1993, the San Carlos Apache Tribe in 1999 and the Zuni Tribe on the Little Colorado and the Gila River Indian Community (GRIC) in 2002.^[1]

During the next 30 years, SRP dealt with an increasing customer base as the population of the "Valley of the Sun" increased by several million. SRP celebrated its 100th anniversary in 2003. A drought significantly reduced the Roosevelt Lake water supply, and as the water level decreased, willow and salt cedar trees began lining its banks, becoming a home for several bird species including the endangered southwestern willow flycatcher.^[1]

If and when the water level increased, this new bird environment would be eliminated, so SRP received a permit from the US Fish and Wildlife Service to offset the impacts to the flycatchers and three other protected bird species. SRP created the Roosevelt Lake Habitat Conservation Plan, establishing 2,200 acres of permanent flycatcher habitat in riparian zones across central Arizona to provide the birds with a new and more permanent home.^[1]

In 2004 Congress passed the Arizona Water Settlements Act that resolved many of Arizona's water issues and resolved tribal water disputes.^[1]

In 2010 the White Mountain Apache Water Rights Quantification Settlement Judgment and Decree ended conflicts between SRP, the state and the Tribe. This agreement was of special importance because the headwaters of the Salt River are on Apache land.^[1]

SRP remains a community-based nonprofit utility annually supplying nearly 800,000 acre-feet of water and power to more than a million customers.^[1]

Sources:

 
Drought

Researchers analyzing tree rings from southern Montana to northern Mexico and between the Pacific Ocean and the Rocky Mountains identified past moisture levels and found that severe droughts were marked by a lack of soil moisture. They also discovered that megadroughts occurred repeatedly in that region between 800 and 1600, confirming that droughts were a natural occurence.^[16]

But climate change has made droughts far worse than those of the past. Human-caused climate change responsible for about 42% of the soil moisture deficit since 2000. Warmer temperatures increase evaporation, drying soil and vegetation.^[16]

In 2018 and early 2019 Arizona Department of Water Resources (ADWR) and Central Arizona Project (CAP) led nearly 40 stakeholders through months of public and small group meetings with the goal of negotiating reductions from Colorado River allocations.^[4]

In 2020 and 2021 the river operated at Tier Zero status, requiring Arizona to forego 192,000 acre-feet of the state's 2.8-million acre-foot annual entitlement to Lake Mead. The reduction was entirely from the CAP system.^[3]

In August 2021 the U.S. Secretary of the Interior declared the first-ever Tier 1 shortage for Colorado River operations requiring Arizona to further reduce uses to a total of 512,000 acre-feet from the CAP.^[3]

On February 14, 2023 Lake Powell, about 22% full, dropped to a record low of 3,522 feet above sea level, the lowest it has been since it was filled in the 1960s. The level is expected to continue declining until May, when mountain snowmelt will join streams flowing into the lake.^[10]

The bottom of Lake Powell is now covered by a layer of Colorado River sediment, estimated to be at least 100 feet thick. The layer is called the Dominy formation, named after Floyd Dominy, who led Glen Canyon Dam construction as the head of the Bureau of Reclamation. Dominy claimed that it would take thousands of years for the reservoir to fill with sediment.^[11]

In 2022, Cathedral in the Desert, a feature that has not been visible since the 1960s, could be accessed by boat. By 2023 visitors had to secure boats downstream and walk 15 minutes along a small creek through which even small boats cannot pass. As the reservoir continues to decline, the journey by foot will increase.^[11]

Some environmentalists view Lake Powell's decreasing water supply as an opportunity for the area to return to its natural state, before the Glen Canyon Dam was built. Because the water level has declined, however, hydropower turbines are now using warm surface water, making conditions more hospitable for non-native fish which are competing with native species.^[11]

The seven Colorado River Basin States, along with water entitlement holders in the Lower Basin, developed Upper Colorado River Basin Drought Contingency Plan and a Lower Colorado River Basin Drought Contingency Plan.^[1] The Upper and Lower Basins of the Colorado were each allocated 7.5 million acre-feet of water.

The Upper Basin plan is designed to:

• protect critical elevations at Lake Powell
• assure compliance with the 1922 Colorado River Compact
• authorize storage of conserved water in the Upper Basin for a future Demand Management Program.^[1]

• require Arizona, California, and Nevada to contribute additional water to Lake Mead storage
• incentivize additional voluntary conservation of water to be stored in Lake Mead.^[1]

• endorsed both the Upper Basin and Lower Basin draught contingency plans
• agree to implement both draught contingency plans in good faith
• agree to consult during operations to avoid future litigation
• reserved legal rights in the future.^[1]

On August 16, 2022 the Department of the Interior declared that the Colorado River will operate in a Tier 2 shortage condition starting in January, 2023. The Department estimated that Lake Mead's water level will fall below 1,050 feet above sea level, the Tier 2 threshold.^[5]

A Bureau of Reclamation and Western Illinois University study concluded that it was possible and extremely expensive to move water from the Mississippi River to the drought-stricken west, but at $1,700 per acre-foot requiring an 88-foot diameter pipe. And there are no guarantees that the Mississippi will not experience drought.^[12]

The Arizona Department of Water Resources provides extensive resources on the current conditions of the Colorado River.^[2]

Drought has led to additional problems for some Arizona residents. Rio Verde Foothills is an unincorporated community of about 2,200 homes outside of Scottsdale, which has been trucking water to about 500 Rio Verde homes.^[6]

More than ten years ago Scottsdale warned Rio Verde residents that they would need to find a different water source.^[6] In November 2021 Scottsdale notified Rio Verde that the Colorado Tier 1 shortage and the city's drought management plan required the stoppage of water deliveries as of January 2023.^[7] Scottsdale officials said their first responsibility was to Scottsdale residents.^[6]

Some Rio Verde property owners banded together to try to create their own water improvement district. But the Maricopa County Board of Supervisors voted down their petition, citing other residents' objections that claimed properties could be condemned to build a new water delivery system.^[6]

In October 2022 Canada-based water company, Epcor Utilities, filed an application to supply Rio Verde Foothills with water. If the project were approved the utility would have to purchase land and construct a standpipe and drill a new well, which could take two to three years. Only homes built before 2024 would receive water provided by Epcor.^[6]

Hobbs also ordered the creation of a new Water Policy Council, with the goal of updating the 1980 Ground Water Management Act. That act requires subdividers in Maricopa, Pinal and Pima counties to prove that 100 years of assured water supply exist for proposed housing developments.^[8] That proof must include legal availability, financial availability, good quality, physical availability and renewable resource availability.^[15]

January 2023 snows provided a slight improvement to Arizona's drought situation. At the Verde River watershed snowpack as of February 1, 2023 was about 300% of normal and twice winter's usual peak accumulation. SRP predicted that Horseshoe and Bartlett reservoirs will fill to capacity and spill as much as 100,000 acre-feet.^[13]

In February 2023 the Mesa City council approved $3.4 million for funding to on drill 12 new groundwater wells by 2029. On March 6, 2023 the council decided to spend $13 million to build a new 10-mile pipeline to deliver some city reclaimed water to the Gila River Indian Community.^[14]

At the Salt River watershed snowpack was about 111% of normal and about 95% of the typical winter peak. SRP's 2023 prediction states that Roosevelt Lake will reach approximately 90% capacity in spring 2023.^[13]

• Cutting agriculture uses. About 80% of Arizona's Colorado River water is used for agriculture. According to former governor Bruce Babbit planting crops requiring less water, limiting irrigation evaporation and retiring about 10% of land used for agriculture would conserve water supplies.^[17]
• Limiting water use and evaporation in urban areas. The Las Vegas community used 23 billion gallons less water in 2020 than in 2002, despite a population increase of more than 780,000 residents. Since 1999 the city replaced about 197 million acres of grass with desert landscaping. The Nevada legislature passed a law prohibiting Colorado River water from being used to irrigate decorative grass.^[18]
• Slash carbon emissions. All future droughts will be less severe if Earth's warming is stabilized at about 3.6^oF (2^oC) above 19th-century levels.^[17]

Sources:

In 1968 President Lyndon B. Johnson signed the Colorado River Basin Project Act, authorizing construction of CAP by the U.S. Department of the Interior's Bureau of Reclamation. The system enabled 1.5 million acre-feet of Arizona's allotment to be delivered to population centers and reduced groundwater for agriculture and other activities.^[1]

In 1971 the Central Arizona Water Conservation District (CAWCD) was created to provide Arizona a means to repay the federal government for the reimbursable costs of construction and to manage and operate the physical system. CAWCD is usually referred to as Central Arizona Project (CAP).^[1] CAWCD consists of Maricopa, Pima and Pinal counties.^[2]

CAP is a non-profit public utility governed by a 15-member volunteer board of directors. Ten are elected from Maricopa, four from Pima, and one from Pinal counties. They meet twice per month and serve six year terms.^[1]

CAP's operations are managed by a staff of 500, responsible for maintenance, operations, business management, public outreach and resource management.^[1]

CAP construction cost $4 billion. It began at Lake Havasu
Lake Havasu with Lake Havasu City,
Arizona on the east shore
D. Searls
Sep. 23, 2007
Wikipedia Lake Havasu
https://en.wikipedia.org/
wiki/Lake_Havasu#/media/
File:LkHavasu.jpg
CC BY-SA 2.0
in 1973 and was completed 20 years later south of Tucson.^[1]

The canal is 336 miles long. Fourteen pumping plants lift the water more than 2,900 feet before it starts its journey to Tucson, which takes between five and seven days. On its way, the water passes through the hydroelectric pump and generating plant at New Waddell Dam,
New Waddell Dam
U.S. Bureau of Reclamation
May 31, 2011
Wikipedia New Waddell Dam
https://en.wikipedia.org/
wiki/New_Waddell_Dam#/media/
File:New_Wadell_Dam.jpg
public domain
the Lake Pleasant storage reservoir and 39 gates controlling water flow. There are also 50 water delivery turnouts.^[1]

The first part of the canal system is wider and deeper, acting as an internal reservoir, holding 20% of the system water. The canal descends approximately 5 inches per mile. On its way, about 1% of the annual flow, 16,000 acre-feet per year, is lost to evaporation.^[1]

Some Arizonans have wondered why CAP isn't covered by solar panels to prevent evaporation, 16,000 acre-feet per year. A study by the Bureau of Reclamation and CAP concluded that they would be difficult to construct and maintain, would need to be adjusted to track the Sun, and would cost about $4 billion to install.^[11]

CAP water is used for residential, business and tribal customers and agriculture for irrigation.^[1]

The Arizona Reconsultation Committee (ARC) meets monthly to discuss the state of the CAP system, reevaluate previous plans and agreements, conservation efforts, and water renewal projects.^[3]

CAP also has an extensive plan for the possible introduction of non-CAP water, called non-project water. CAP continues to work with Arizona cities and tribes, asked for, and received a lot of positive feedback on its potential plans.^[4]

CAP was recently awarded VESP Platinum, the highest level of ADEQ's Voluntary Environmental Stewardship Program (VESP). To achieve VESP Platinum, CAP achieved a measurable environmental improvement, committed to measuring continuous improvement for three years, instituted an active Environmental Management System, and committed community outreach.^[5]

On November 18, 2020, CAP University held its first class. More than 300 members of the public from several Upper and Lower Colorado Basin states signed on to the 3-hour Zoom meeting which addressed CAP background and history, engineering, land development, power usage, drought contingency plan, sustainability efforts, and the steps that CAP takes to keeps its on-site and field employees safe.^[6]

CAP is planning additional CAP University courses that will explore each of these topics in greater depth.^[7]

CAP is part of Water Utility Climate Alliance (WUCA), a coalition of 12 of the nation's largest water providers. WUCA member agencies provide drinking water to more than 50 million people in the U.S. Other members include Austin Water, Denver Water, Metropolitan Water District of Southern California, New York City Department of Environmental Protection, Philadelphia Water Department, Portland Water Bureau, San Diego County Water Authority, San Francisco Public Utilities Commission, Seattle Public Utilities, Southern Nevada Water Authority and Tampa Bay Water. WUCA engages in climate change research, water management decision-making improvement and water supply protection.^[9]

To learn more about the CAP sign up for Central Arizona Project Know Your Water News.^[8]

Sources:

 
Groundwater

In the last 60 years, Arizona's population has grown about 500%, to about 7 million residents. Arizona's water use has declined to less than 7 million acre-feet per year, 3% less than it was in the 1950s.^[1]

The 1980 Groundwater Management Act (GMA) required that its active-management areas (AMAs) find water alternatives other than pumping it out of the ground. This requires conservation efforts by municipal, industrial, and agricultural users which lead to declining per person water use.^[2]

More than 75% of Arizonans live within the Prescott, Phoenix, Pinal, Tucson and Santa Cruz AMAs. ^[2] Four of the five urban AMAs are required to reduce groundwater reliance so that by 2025, they have created a balance between recharge and extraction.^[1]

The act was not created without some controversy. It was the first of its kind in the country, outlawing irrigation on any new acres of farmland and forced subdivisions in more populated areas to show a 100-year water supply before building.^[3]

ADWR measures groundwater levels in Arizona basins on a rotating basis. AMAs and irrigation non-expansion areas (INA)area designated to protect existing agriculture where groundwater is the main water source have priority. These efforts, called basin sweeps, collect well water, groundwater and water quality data used in water management and planning.^[16]

The GMA created the Joseph City and Douglas INAs. The Douglas INA became and AMA in 2022. The Harquahala INA was created in 1981 and the Hualapai Valley INA in 2022, They are administered by ADWR.^[21]

On June 28, 2021, ADWR updated groundwater conditions in the Pinal AMA. The results demonstrated that between 2016 and 2115 groundwater demand would exceed supply by 8 million acre-feet.^[15]

In January 2023, ADWR published the Hassayampa Groundwater Model, which projects water use west of the White Tank mountains and northwest of Phoenix. The analysis determined that demand would exceed supply by 4.4 million acre-feet of groundwater over a 100-year period for the area, meaning that future subdivisions relying on groundwater would not be approved.^[15]

Outside AMAs there are few groundwater use restrictions, resulting in limited legal protections for local communities that want to prevent new and existing groundwater user from overpumping, reducing groundwater reserves and creating potential shortages.^[2]

Counties and municipalities outside AMAs can sign up for additional protections. Cochise and Yuma Counties and Clarkdale and Patagonia require new development to prove it can meet the 100 year water requirements of AMAs.^[2]

The San Pedro and the Verde Rivers flow because of groundwater, but Arizona water law does not adequately protect the relationship between groundwater and surface water.^[2]

When Colorado River supply exceeds demand, municipalities can store the excess water underground, earning long-term storage credits. The state tracks those credits, and cities can then return that water into the ground when needed. Reclaimed water, however, earns fewer storage credits.^[2]

In 1993 the Arizona State legislature created a groundwater replenishment authority to be operated by the Central Arizona Water Conservation District (CAWCD) throughout its three-county service area. This replenishment authority of CAWCD is called the Central Arizona Groundwater Replenishment District (CAGRD).^[4]

CAP's Non-Indian Agricultural (NIA) supplies are 65% of CAGRD's water supply portfolio, They were reduced in the 2022 Tier 1 shortage and will be eliminated in the 2023 Tier 2a shortage. Other CAP supplies may be reduced in the future.^[11]

CAGRD has been preparing for less CAP water by acquiring long term storage credits (LTSC), which have enabled CAGRD to acquire reliable assets meeting replenishment obligations for 20 years in the Phoenix AMA, and longer in the Tucson and Pinal AMAs, even under severe shortage conditions.^[11]

Every 10 years, as part of its mandatory operation plan, CAGRD sets a target for LTSCs that should be maintained as a water supply reserves. The reserve target for each AMA is equivalent to 20% of the difference between the total 100-year replenishment obligation for that AMA and the total volume of long- and intermediate-term water supplies planned to meet the obligation.^[11]

CAGRD's water acquisition program is focused on securing additional water supplies less susceptible to Colorado River shortage conditions. and will continue to forecast and monitor potential shortage impacts and costs.^[11]

In 1996, the state legislature created the Arizona Water Banking Authority (AWBA). Because farms and cities were not using their full CAP allotments and California had been using the excess Colorado River supply, new water banking laws enabled Arizona to store the unused Colorado allotment in recharge facilities to reduce groundwater overdraft.^[5]

In 1999, the legislature expanded CAWCD's replenishment authorities and responsibilities, passing the Water Sufficiency and Availability Act.^[4]

The USGS used radar to track the changes and found the maximum subsidence of about 2 inches occurred between May 2003 to July 2006, and then declined to 0.9 inches between April 2011 and November 2014.^[6]

Between May 2003 and March 2016, maximum subsidence was as high as 5.3 inches in the Tucson metropolitan area, south of Irvington Road between south 12th Avenue and south Park Avenue. Subsidence was as high as 4 inches in central Tucson south of Broadway between Country Club Road and Craycroft Road.^[6]

The radar data indicated that there was no significant land surface deformation from 2003 to 2016 in Avra Valley.^[6]

There are areas of Arizona outside of AMAs, where groundwater sources are declining. Willcox Basin relies on only rainfall alone for replenishment and is vulnerable during drought.^[12]

When large water-using operations, like the Riverview Dairy, moved in to the area residents noticed that their water disappearing because the dairy was pumping out a lot of groundwater from deep wells, causing residents' wells to dry up.^[12]

A 2018 report from the state water department found that groundwater levels declined by at least 200 feet between 1940 and 2015 in the parts of the Willcox Basin with high agricultural pumping, before Riverview arrived.^[12]

The Willcox Basin groundwater crisis began near the Kansas Settlement and spread across the county as Riverview used more of the aquifers. The crisis now affects Willcox itself, one of the only incorporated settlements in the area, ten miles from the Riverview Dairy.^[12]

Some residents believed that because they lived miles from the dairy, their wells would not be affected, but thousands have experienced dry wells.^[13] They are left to haul water from a Willcox facility.^[12]

Overpumping has produced fissures several feet deep. Some have damaged roads, forcing closures and leaving some residents with worthless property and abandoned homes.^[12]

After Riverview arrived, county politicians pushed for the creation of a municipal water district, which would create communal wells with a reliable water supply. Residents were suspicious because the proposal was supported by the dairy, which helped finance outreach efforts and office space. Some believed rumors that the dairy was going to create a water district for a new planned community. Creation of the water district has currently stalled.^[12]

Years of anti-regulation sentiment have led to a grassroots campaign for restrictions on new wells which could restrict future corporate farming operations.^[12]

Within the 1980 Groundwater Management Act is a provision allowing rural communities to propose a ballot question about whether to establish an AMA. If the ballot question wins a majority vote, the state then appoints a committee to supervise groundwater in the basin. The committee can impose restrictions on new irrigation activity, limiting land area using groundwater.^[12]

A group called the Arizona Water Defenders wants to create a new AMA to regulate groundwater in the conservative Willcox and Douglas Basins. They had no difficulty obtaining the required 250 signatures from Cochise County residents to get the AMA proposal on the ballot.^[12]

The state paused all new irrigation in the area until after the election, stopping the growth of local agriculture. Individual households will not be restricted because their wells are too small to meet threshold regulations, but local farmers may need to comply with a permitting process to drill new wells.^[12]

A group called Rural Water Assurance, co-founded by the president of the county farm bureau, put up billboards along I-10 urging voters to vote no on the AMA. They also filed a lawsuit against the Douglas Basin AMA effort in June 2022, claiming that collected signature were invalid. The lawsuit was dismissed in August.^[12]

If the AMA is created, it can restrict almost all new pumping, but it can't order current users, including Riverview, to stop drawing well water. Basing groundwater levels will continue to drop. Residents will continue to haul water and dig new wells. Water pumping limitations will deter new farms, further slowing the county's economy.^[12]

In October 2022 the city of Queen Creek paid $30 million for 500,000 acre-feet of Maricopa and La Paz county water rights for that water. The city plans on using 5,000 acre-feet per year for the next 100 years. The sellers are part of the Harquahala Valley Water Association and will move the water through the CAP canal.^[18]

On November 8, 2022, Cochise County residents approved Proposition 422 to establish an AMA in the Douglas Basin, joining 82% of Arizona where groundwater is managed by an AMA. Voters rejected a measure by a 2-to-1 margin to create a similar management area in the Willcox Basin, where groundwater withdrawal will remain unregulated.^[14]

In January 2023 the city of Buckeye agreed to pay $80 million for an acre of Harquahala Basin and its water rights. The purchase allows Buckeye to use 5,926 acre-feet per year for the next 100 years. ^[19]

In 2023 Arizona state attorney general Kris Mayes accused ADWR of failing to protect groundwater, by ignoring its responsibility to study the need for new AMAs. The Saudi firm Fondomonte has been pumping groundwater to grow alfalfa in La Paz county to feed Saudi cattle. Mayes promised to cancel the Saudi lease and stated that the use of Arizona's groundwater by the Saudis is illegal, but governor Hobbs said the cancellation is not legally possible. Mayes successfully managed to get the state land department to cancel two requests by the Saudis to drill two additional wells in La Paz county.^[17]

The University of Arizona Project WET provides nine short videos on groundwater storage, pumping, reuse and conservation^[7] and the ASU Kyl Center for Water Policy has an app which the public can use to track Arizona's groundwater level changes.^[9]

Sources:

 
Surface Water

Before June 12, 1919, a person could acquire a surface water right simply by applying the water to a beneficial use and posting a notice of the appropriation where the water was diverted.^[1]

On June 12, 1919, the Arizona Surface Water Code, now known as the Public Water Code, was enacted. The law states that a person must obtain a permit and certificate to use surface water and that "beneficial use shall be the basis, measure, and limit to the use of water within the state."^[1]

Arizona Revised Statute § 45-151(A) defines beneficial uses as "domestic, municipal, irrigation, stock watering, water power, recreation, wildlife, including fish, nonrecoverable water storage pursuant to section 45-833.01 or mining uses..."^[2]

Arizona's protected surface waters include:

• all Waters of the United States (WOTUS)
• any perennial, intermittent and ephemeral reaches and any impoundments of the following rivers, not including tributaries or reaches of waters wholly within tribal jurisdiction or reaches of waters outside of the United States
• Bill Williams River from the confluence of the Big Sandy and Santa Maria Rivers to its confluence with the Colorado River
• Colorado River from the Arizona-Utah border to the Arizona-Mexico border
• Gila River from the Arizona-New Mexico border to the confluence with the Colorado River
• Little Colorado River from the confluence of the east and west forks of the Little Colorado River to its confluence with the Colorado River
• Salt River from the confluence of the Black and White Rivers to the confluence with the Gila River
• San Pedro River from the Arizona-Mexico border to the confluence with the Gila River
• Santa Cruz River from its origins in the Canelo Hills of southeastern Arizona to its confluence with the Gila River
• Verde River from Sullivan Lake to its confluence with the Salt River
• tributaries to the Bill Williams River, the Colorado River, the Gila River, the Little Colorado River, the Salt River, the San Pedro River, the Santa Cruz River and the Verde River
• all lakes, ponds and reservoirs that are public waters used as a drinking source, for recreational or commercial fish consumption or for water-based recreation such as swimming, wading and boating and other types of recreation in and on the water^[3]

• those used as a drinking water source, including ditches and canals
• public waters used for recreational or commercial fish consumption
• public waters used for water-based recreation such as swimming, wading, boating and other types of recreation
• wetlands adjacent to waters on the protected surface waters list
• waters of the state that cross into another state, the Republic of Mexico or the reservation of a federally recognized tribe^[3]

Sources:

 
Water Quality

The 1974 Safe Drinking Water Act (SDWA), amended in 1986 and 1996, authorizes the United States Environmental Protection Agency (EPA) to set national standards for drinking water to protect against both naturally-occurring and man-made contaminants. The EPA, states and water systems work together to make sure the standards are met.^[1]

Drinking water protection begins with an assessment of the quality of all public water sources and continues through regulations that govern water system design and construction. Drinking water quality is assured through scheduled tests for potential contaminants. Test results are reported to the ADEQ (Arizona Department of Environmental Quality) Water Quality Division (WQD) and a summary provided to customers annually.^[2]

• regulating treatment and discharge of wastewater and reclaimed water
• monitoring surface and groundwater quality and developing groundwater safety standards
• identifying water pollution, developing solutions and facilitating implementation
• issuing permits to protect water from pollution point sources, such as sewage treatment facilities, septic tanks, and mining operations
• investigating complaints and violations of water quality laws
• providing information to well owners whose wells may have been polluted or damaged after wildfires.^[2]

ADEQ also monitors the general health of Arizona's waters by:

• utilizing a Pesticide Contamination Program that prevents groundwater contamination from pesticide use
• publishing an annual report that describes any potential impacts on groundwater.^[2]

• monitoring stream and lake water quality

Arizona Water Classifications[9]
classification	description
A+	wastewater that has undergone secondary treatment, filtration, nitrogen removal treatment and disinfection
A	wastewater that has undergone secondary treatment, filtration and disinfection
B+	wastewater that has undergone secondary treatment, nitrogen removal treatment and disinfection
B	wastewater that has undergone secondary treatment and disinfection
C	wastewater that has undergone secondary treatment in a series of wastewater stabilization ponds including aeration and with or without disinfection

• assessing surface water quality standards
• developing a total maximum daily Load (TMDL) plan to reduce pollutants
• working with public and private interests to develop and fund restoration projects
• creating educational opportunities for the public to learn about ways to protect Arizona's water resources
• implementing the Arizona Pollutant Discharge Elimination System (AZPDES) program, which requires all facilities that discharge pollutants into streams and lakes to obtain a permit.^[2]

SRP utilizes computer modeling to track nitrateusually combined with sodium or potassium and used as a fertilizer levels. Nitrate is found naturally in lakes, rivers and well water, but high nitrate levels can be unsafe.^[3]

Central Arizona Project (CAP) has a monitoring program providing water users with real-time measurements and monthly and quarterly sample results.^[4] CAP's Water Quality website also includes publicly-accessible annual reports listing detailed information on water samples, chemical components, and pollution.^[5]

Some cities, including Phoenix, issue their own water quality reports. Phoenix's reports are colorful, easy-to-read, and written in language that consumers can understand.^[6]

Sources:

On January 1, 2018, the state of Arizona enacted Arizona Administrative Code, Title 18 Chapter 9 R18-9-E701 Recycled Water Individual Permit for an Advanced Reclaimed Water Treatment Facility,^[1] allowing direct potable reuse (DPR). Before that date, advanced water treatment (AWT) water was not allowed in Arizona drinking water.^[2]

In November, 2019, Scottsdale Water and Scottsdale Arts held the One Water Brewing Showcase to introduce the public to the idea of recycled potable wastewater. Ten Scottsdale breweries participated.^[3]

Scottsdale was the third city in the U.S. to receive a permit for DPR and was the first in Arizona. The utility spent 18 months working with the Arizona Department of Environmental Quality (ADEQ) establishing the process to obtain this special permit.^[3]

The Advanced Water Treatment (AWT) Plant at the Scottsdale Water Campus has been using indirect potable reuse (IPR). The plant had been returning ultrapure water into the drinking water aquifera body of permeable rock which can contain or transmit groundwater for more than 20 years, recharging over 70 billion gallons into regional aquifers since 1988.^[3]

While AWT water is ultrapure and cleaner than bottled water, Scottsdale is not planning on including DPR in its water supply, and will continue to rely on its diverse water sources, including IPR to recharge its aquifer for future use.^[3]

Other cities are pursuing DPR as a long-term water source. Scottsdale's permitting experience provides a model for obtaining an ADEQ DPR permit.^[2]

 
Lakes and Recreation

Colorado River and Salt River dams and Arizona's natural canyons have created several large lakes and recreation areas homes to a large variety of birds and plants. Water depth also serves as an indicator of drought and environmental conditions.^[1] When Lakes Mead and Powell are full, they can hold nearly four years of Colorado River water, but a drought that began in 2000 has caused significant drops in both lakes.^[2]

• Salt River Project Reservoirs and Lakes➔
• Roosevelt Lake, located in Gila County and created in 1911 on the Salt River as the result of Roosevelt Dam, is the largest lake in Arizona with an area of more than 21,500 acres, about 33.6 square miles. The lake has a marina for fishermen and boaters, and is home to many bird and plant species.^[3]



• Apache Lake is on the Salt River, southwest of Roosevelt Lake and northeast of Tortilla Flat. The lake is a little more than 4 square miles. It is nearly surrounded by steep cliffs and the only on-land access is via the Apache Trail road.^[4]
• Saguaro Lake, about 1.9 square miles, is located in the Tonto National Forest, and was formed by the Stewart Mountain Dam, which was completed in 1930. It was the last of the reservoirs to be built on the Salt River. The lake has 22 miles of shoreline and offers boating, kayaking, sailing, skiing, jet skiing, fishing and camping.^[5]
• Canyon Lake at about 1.5 square miles is the smallest of the Salt River Project lakes. The lake is surrounded by steep cliffs.^[6]
• Verde River Reservoirs and Lakes➔
• Bartlett Lake and Reservoir, about 3.1 square miles, is located in the Tonto National Forest. The lake has a marina and is used for a variety of water sports.^[7]
• Horseshoe Lake and Reservoir, about 1.2 square miles, is a man-made lake that serves as one of several reservoirs for the Phoenix area. Its waters are the result of the Horseshoe Dam.^[8]
• C.C. Cragin Blue Ridge Lake and Reservoir were built in 1965 by Phelps Dodge, and later transferred to the SRP. It is a tiny, approximately 0.1 square mile lake, but an important water source for the town of Payson, Arizona.^[9]



• Colorado River and CAP System Reservoirs and Lakes➔
• • Lake Powell, located in northern Arizona and southern Utah, is a 254 square mile reservoir. It's part of the Colorado River in Glen Canyon National Recreation Area and has almost 2,000 miles of shoreline and beautiful scenery.^[10]
  • Lake Mead, about 247 square miles, has more than 750 miles of shoreline, and is the largest reservoir in the U.S.^[11]
  • Lake Mohave, 41.4 square miles, was created in 1951 following the completion of Davis Dam near present-day Laughlin, Nevada, and Bullhead City. It extends from Hoover Dam to Davis Dam.^[12]
  • Lake Havasu, about 30 square miles, is the home of the London Bridge. It provides camping, boating and the Arroyo-Camino Interpretive Garden that displays the natural park life.^[13]
  • Lake Pleasant Regional Park is 23,362 acres, or about 11.6 square miles, and provides a variety of water-related activities. It is part of the CAP waterway system. Water usually reaches its highest levels in March and April and its lowest in October and November.^[14]
  • Canyon Lake, the smallest SRP lake at about 1.5 square miles, is located 45 miles from Phoenix and a few miles from Tortilla Flat. Visitors can swim and fish.^[15]

• Gila River Reservoirs and Lakes➔
• San Carlos Lake 30.5 square miles, made by the Coolidge Dam, lies within the 3,000 square miles of the San Carlos Apache Indian tribal lands, located approximately 125 miles east of Phoenix. A permit is required for hiking, fishing, camping, and off-highway driving.^[16]
• Other Reservoirs and Lakes➔
• At 6,000 feet in altitude, Lyman Reservoir, in northeastern Arizona, was created as a 1,500 acre irrigation reservoir by damming the Little Colorado River. It is fed by the melted snow of Mount Baldy and Escudilla Mountain, the second and third highest mountains in Arizona. It is surrounded by a 1,200-acre park. The watershed extends to New Mexico.^[17]

There are many small recreational lakes in Arizona. Most are located in national forests and provide fishing, camping, kayaking, swimming, boating and other recreational facilities.

Alamo Lake is in the Bill Williams River Valley in eastern LaPaz and Mohave counties.

Apache-Sitgreaves National Forest is the home of Bear Lake, Black Canyon Lake, Carnero Lake, Chevelon Canyon Lake, Cresent Lake, Knoll Lake, Luna Lake, Rainbow Lake, River Reservoir, Willow Springs Lake and Woods Canyon Lake. The forest runs through Coconino, Navajo, Apache and Greenlee counties.

Kaibab Lake is in Kaibab National Forest, adjacent to the northern and southern rims of the Grand Canyon.

Becker Lake, Big Lake, Hawley Lake and Reservation Lake are in the White Mountains, and the last two of these lakes are within the boundary of the White Mountain Apache Indian Reservation, near the Arizona-New Mexico border.

Goldwater Lake and Lynx Lake are in the Prescott National Forest, north of Prescott and west of Williams.

Parker Canyon Lake, Patagonia Lake, Pena Blanca Lake, Riggs Flat Lake, Rose Canyon Lake and Roper Lake are in the Coronado National Forest. This forest covers parts Cochise, Graham, Santa Cruz, Pima and Pinal Counties, and is the forest best known to Tucsonans. It is home to a summer escape spot, Mt. Lemmon.

Martinez Lake is a small lake located in the southwestern corner Arizona, about 60 miles north of Yuma.

Aguirre Lake, is located in Buenos Aires National Wildlife Refuge, and Arivaca Lake is located near the old Ruby Road, among grasslands surrounded by rock formations and mountain views.

Sources:

 
Conservation^[*]

The oldest reclaimed non-potable water system is in Grand Canyon Village, Arizona, which has been using reclaimed water for nonpotable uses since 1926.^[13]

In 1973 the Arizona Municipal Water Users Association (AMWUA) negotiated an agreement among five member cities and Arizona Public Service to provide treated wastewater to the Palo Verde Nuclear Generating Station. It is the only nuclear power facility in the U.S. cooled by recycled water.^[14]

In 1999 Mesa, Scottsdale and Phoenix started the Water - Use It Wisely campaign, based on the "Don't tell us to save water. Show us how" concept. The campaign developed a 10-part video series on xeriscaping and tips and guides on water conservation.^[17]

The Water - Use It Wisely partnership now includes:

• cities: Tempe, Peoria, Chandler, Buckeye, Glendale, Avondale, Goodyear, Surprise, Fountain Hills, Queen Creek, Flagstaff, Bullhead City, Gila Resources, Lake Havasu City, Sedona, Yuma, Safford, RIo Verde, El Mirage, Prescott Valley and Tucson
• water-related providers: AMWUA, Central Arizona Project (CAP), Global Water Resources, EPCOR Water and Salt River Project (SRP), Cochise Water Project, Granite Oaks Water Users Association
• government agencies: Federal Bureau of Reclamation, Luke Air Force Base^[17]

In 2010 the Governor's Blue Ribbon Panel on Water Sustainability recommended conservation and recycling strategies.^[15]

In 2012 the Steering Committee for Arizona Potable Reuse (SCAPR) was formed "To guide Arizona water interests in identifying and mitigating impediments to potable reuse (real or imagined) within industry standards of practice."^[15]

Arizona's Next Century: A Strategic Vision for Water Supply Sustainability stated that direct potable reuse (DPR)involves the treatment and distribution of water without an environmental buffer exploration was necessary due to increasing water demand. The report established a 10-year plan, including a review of legal and institutional barriers to DPR. The report stated that reclaimed water could offset projected state water imbalances by about 50%.^[16]

Arizona has a good start on establishing DPR regulations. Arizona Department of Environmental Quality (ADEQ) set stringent treatment standards for new and expanding wastewater treatment plants that require nitrogen reduction to below drinking water limits and removal of fecal coliform bacteria, an indicator of pathogensa virus, bacteria or fungus that causes disease to non-detectable levels. Water quality standards are designated in rule for five reclaimed water quality classes, based on human health protection and an effective permit system expanded safe reclaimed water use.^[16]

AMWUA cities now recycle more than 95% of their treated wastewater to sustain fishing lakes, create wetlands, irrigate fields and parks and store underground for future use.^[14]

We have planned and invested in robust and resilient water supplies, infrastructure and processes so that your local water provider can deliver you water every day of every year. Through our collaborative efforts, we can bring water from Arizona's mountains and the Colorado River, and manage our groundwater.

We are each taking extra precautions by implementing resiliency plans that have been developed for times like these to better ensure essential operations continue without interruption and we can fully support local water providers - all of which could not be achieved without the dedicated efforts of all of our employees.

Together we remain committed to safeguarding our water supplies so they remain secure not just for today, but for the future.^[1]

Municipal:

• large municipal water providers with a designation of assured water supply participate in the Gallons Per Capita Per Day (GPCD) program or the Modified Non-Per Capita Conservation Program (Modified NPCCP)
• large municipal water providers without a designation of assured water supply must participate in Modified NPCCP
• large municipal provider distribution system losses cannot exceed 10% annually.^[2]

• allotment-based requirements for large turf facilities, dairies and feedlots
• best management practices or design limitations required for mines, cooling towers, sand and gravel operations, large scale power plants and new large landscape users.^[2]

• no new agricultural acreage in production
• each farm, with an irrigation grandfathered right, is assigned a maximum annual groundwater allotment, based on assumed irrigation efficiencies of 65% to 80%
• planting guayule, a low-water-use, desert-adapted shrub used as a natural rubber source for tires^[10]
• some farms have enrolled in an optional best management practices program
• irrigation district distribution system losses are not to exceed 10%.^[2]

Runoff within the Salt River system occurs earlier in the season than in other parts of the country. This results in lower water loss and less evaporation than other parts of the country.^[3]

CAP has made several water conservation suggestions to consumers:

• save water by turning off the faucet while tooth brushing, adding to the efforts of thousands of Arizona citizens
• use a broom instead of water to clean outdoor surfaces, such as driveways and sidewalks, most garden hoses use about ten gallons per minute
• repair water-related fixtures, the EPA estimates that an average household wastes about 10,000 gallons of water every year through leaks, enough to fill a backyard swimming pool
• install more low-water use fixtures
• capture Arizona's rainwater through harvesting efforts.^[4]

CAP also provides additional suggestions on reducing, reusing, recycling, conservation and natural resource protection that work hand-in-hand with water conservation efforts.^[5]

In 2018 ADWR published a report that listed Arizona's municipal water providers designated as having an assured or adequate water supply.^[6]

Reclaimed water has many applications.

Urban:

• irrigation of public parks, sporting facilities, private gardens and roadsides
• street and vehicle cleaning
• fire protection systems
• toilet flushing
• air conditioners
• dust control^[7]

• food crops both commercially and not commercially processed
• pasture for milking animals and fodder
• fiber, seed crops and ornamental flowers
• orchards, greenhouses and viticulturecultivation and harvesting of grapes
• hydroponic culture and aquacultureraising and harvesting of living creatures found in water environments
• industrial uses
• processing and cooling water and recirculating cooling towers
• making concrete, soil compaction and dust control^[7]

• golf course irrigation
• fishing, boating and bathing
• snow production^[7]

• aquifer recharge, wetlands, marshes and stream augmentation
• wildlife habitat
• tree cultivation^[7]

• aquifer recharge for drinking water use
• augmentation of surface drinking water supplies
• treatment until drinking water quality^[7]

ADWR's Assured and Adequate Water Supply programs address limited groundwater supplies. Both programs evaluate the availability of a 100-year water supply considering demand and growth.^[9]

The Adequate Water Supply Program operates outside of the AMAs to ensure water inadequacy and supply limitations disclosed. Water supply adequacy must be demonstrated prior to plat approval and issuance of a public report.^[9]

The publicly available ADWR Water Management Assistance Program (WMAP) Dashboard provides financial and technical resources in development and implementation of conservation programs, facilitation and augmentation of renewable water supply utilization, information on hydrologic conditions and water availability in an AMA.^[12]

ADWR also provides additional conservation-related resources for the public, water providers and agricultural, commercial, industrial and institutional water users.^[8]

Many Arizona cities, including Avondale, Chandler, Glendale, Mesa, Paradise Valley, Peoria, Phoenix, Scottsdale, Surprise, Superior, Tempe and Tucson, host xeriscapinglandscaping requiring little or no irrigation demonstration gardens where visitors can learn how to install and maintain low-water use desert gardens.^[11]

Sources:

 
Legal History^[*]

The Colorado River is managed and operated under federal laws, court decisions, state and international agreements and regulatory guidelines. These consitute the "Law of the River."^[1] There are also many minutesan official record of what was said and done in a meeting between the U.S. and Mexico.

 
[*] Some of the Legal History section materials posted in this site originally posted at the Homestead Acts → 1840-1899 and Homestead Acts → 1900-1930 sections of Journalism 455/555 Environmental Journalism and John Wesley Powell, 1834-1902, http://denisemeeks.com/journalism/jour_555/powell/ by this author

 
Resources

Denise Meeks, dmeeks@arizona.edu