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Colorado RiverColorado River

Drainage Basin250,000 mi2

1,450 miles long

Originates at over 10,000 ft in the Rocky Mtns in CO

Flows in the Gulf of California

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Colorado RiverColorado River

Stakeholders:

Seven western states (CO, WY, UT, NM, AZ, NV, CA)Federal GovernmentDozens of Indian tribesMexico

Use of Colorado River water:

3.5 million acres of farmlandelectricity for 3 million peopleWater for ~25 million people (Denver, Salt Lake City, Las Vegas, Phoenix,San Diego and 100’s of other communities)

Colorado RiverColorado River

Controversial issues:

Allocations for individual statesWater transfers from agriculture to urban usersEndangered species and other environmental issuesRecreation American Indian water rights

Extenuating circumstances:

Water allocations to states in the 1920’s based onunrealistically high flows

Prolonged recent drought

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Colorado River Flow at LeeColorado River Flow at Lee’’s Ferrys Ferry

Long term average flow ~15 million ac-ftLarge year-to-year fluctuations (5-25 million ac-ft)Frequent long drought cyclesWater allocations in the 1920’s based on higher than

average flow

History of the Colorado River BasinHistory of the Colorado River Basin

• 600 AD Anasazi Indian develop a canal system for irrigationand drinking water in Chaco Canyon, NM. Used untilmid-1100’s

• During the same time, Hohokam Indians built 250 miles ofcanals for water from the Salt and Gila Rivers. Useduntil the 1400’s

• Spanish explorers looking for gold in the 1600’s

• 1857/58 steamboat expedition 420 miles upstream

• 1869 John Wesley Powell led three wooden row boats downthe Colorado through Grand Canyon

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Water DevelopmentWater Development

• From the beginning upper-basin states were concerned that California could establish senior appropriative rightsbefore they could use their water

• First water use by Imperial Valley, CA farmers via canal throughMexico

• Farmers wanted a canal that was entirely on US territory, the“All-American Canal” but need Congressional support

• Congressional support required an agreement of Basin states

• 1902 Bureau of Reclamation established which promptly developsa comprehensive plan for Colorado River development

• 1905 - headgates of Imperial Valley Canal flooded divertingentire river into a natural low spot creating the Salton Sea

• Flooding and 1910 Mexican revolution provided additionalimpetus for construction of the All-American Canal

• 1920 – 7-State compact proposed

• 1923 – 6-State compact reached (AZ did not agree)

Upper basin to send 75 million ac-ft downstream overeach 10-year period (7.5 million ac-ft per year on average)to California and Nevada

California’s allocation is 4.4 million ac-ft plus not morethan half of any surplus water

Arizona was concerned because the compact did notallocate a specific amount of water to each state

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6-State compact sets the stage for major water projects

• 1931 - Boulder Canyon (Hoover) Dam

• 1940 - All-American Canal

• 1941 - Colorado River Aqueduct to San Diego and LA area

• 1944 – After repeated appeals and loss in Supreme Court,Arizona signed on to 6-State compact and started to pursueits own federal water projects (Central Arizona Project pumping water up to Phoenix and Tucson)

• 1963 – Glenn Canyon Dam

• 1968 – Grand Canyon Dam eliminated

Current Issues Current Issues –– Upper Colorado BasinUpper Colorado Basin

The upper basin states have yet to fully use their shareof Colorado River water (6 million ac-ft) in most years. However, demand is rising.

• 52% Colorado• 23% Utah• 11% New Mexico• 14% Wyoming

Current controversial issues

Growth and increasing water demandProlonged droughtDemands for endangered fish species

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Current Issues Current Issues –– Lower Colorado BasinLower Colorado Basin

Water use is constantly increasing. In 1989, for the first time, the lower basin used up its entire 7.5 m ac-ft allotment.

California has been using more than its 4.4 m ac-ft Apportionment every year since 1985 but will need to reduce water use because growth in other states will use up any surplus.

Largest user of water is agriculture, Imperial Irrigation District alone uses 2.8 m ac-ft per year to irrigate a 25x40 mile area in the southeast of California.

Under pressure from the Federal Government, in 2003 California agreed to reduce water use by conservation measures in theImperial Valley and transfer 200,000 ac-ft from IID to San Diego.

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Salton SeaSalton Sea

In 1905 the headgates of the Imperial Canal flooded, redirecting the entire Colorado River into a natural low spot, the Salton Sink.

This accident created California’s largest freshwater lake (375 mi2).

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Salton Sea has no natural outlet and has become increasingly saltier.

Currently about 4.8% salt.

Salton Sea is now fed by 1.3 m ac-ft per year of irrigation return flow.

A productive fishery for salt water fish is threatened by increasing salinity.

Salton Sea has become a major stop for migrating birds (408 species).

“Wasteful” water use by Imperial Valley Farmers maintains theSalton Sea.

If water is used more efficiently so some if it can be transferred to San Diego, salinization of the Salton Sea would accelerate and the sea would eventually dry up.

Options for dealing with the Salton Sea:

• Do not irrigate land and put fresh water in the lake

• Evaporation ponds to concentrate salts in parts of lake (~$1.6 b)

• Use water for cities and agriculture and let lake dry up

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Environmental and recreational treasure?

Salty wasteland?

Salton SeaSalton Sea

Long Term Issues for Colorado Basin Long Term Issues for Colorado Basin --Water QualityWater QualityThe name sake reddish color of the Colorado River is due to large amounts of sediment and dissolved minerals (salts).

Colorado River carries 9 m tons of salt annually and flows through a region where soils and sediments are salty to start with.

At the intake of the Imperial Canal, water contains 2000 lb of salt per ac-ft.

Because the Colorado River is not flowing into the ocean anymore, all this salt remains in the basin and accumulates on irrigated lands.

Water quality decreases downstream with Mexico getting the worstwater.

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Water quality dramatically worsened in the 1960’s

• Closing of Glenn Canyon Dam• A Bureau of Reclamation project in the Wellton Mohawk area

with poor drainage and salty soils adds irrigation return flow containing 6,300 ppm TDS to the Colorado.

Colorado River salinity in Mexico increased from 800 ppm to 1500 ppm TDS

1973 Treaty to improve Mexico water quality

$250 m Yuma Desalination Plant for treating 80,000 ac-ft of water from 60,000 ac of salty farmland east of Yuma.

Desalination facility operated briefly in 1992 but flooding of the Gila River washed out delivery facility. Has not operated since.