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1907
MAY 13, 1907Colorado River History
Doctrine of Equitable Apportionment Adopted

U.S. Supreme Court adopts the doctrine of equitable apportionment of benefits for rivers flowing between states.  Kansas v. Colorado, 206 U.S. 46.  The equitable apportionment doctrine is based on the “cardinal rule” of “equality of right” among states.  “Each state stands on the same level with all the rest.”  The Court later explains that “equality of right” refers “not to an equal division of the water, but to the equal level or plane on which all the states stand, in point or power and right, under our constitutional system.”  Wyoming v. Colorado, 259 U.S. 419, 465 (1922).

1919
1919Colorado River History
League of the Southwest Organized

Seven basin states organize League of the Southwest in Salt Lake City to promote Colorado River development.

1921
1921Colorado River History
Equitable Division and Apportionment Authorized

Congress authorizes the seven basin states to negotiate and enter into an interstate compact providing for the equitable division and apportionment of the Colorado River.

1922
January 26, 1922Colorado River History
Colorado River Commission Organized
The Colorado River Commission is organized at Washington, D.C.
1922Colorado River History
Fall-Davis Report Submitted

The Fall-Davis Report submitted to Congress recommends construction of the All-American Canal in California and a dam at Boulder Canyon in Nevada.

June 5, 1922Colorado River History
Wyoming V. Colorado

U.S. Supreme Court rules that the doctrine of prior appropriation can be applied between states where each of the states adheres to that doctrine.  Wyoming v. Colorado, 259 U.S. 419.

November 24, 1922Colorado River History
Colorado River Compact Signed

• First agreement to legally connect the states that share the Colorado River water supply

• Designated the Upper and Lower Colorado River Basins, allocating 7.5 MAF/year to each

• Arizona refused to ratify the Compact until 1944

1923
January 26, 1922Colorado River History
Colorado River Compact Ratified

All states, except Arizona, ratify the Colorado River Compact.

1928
December 21, 1928Colorado River History
Boulder Canyon Project Act of 1928

• Authorized construction of Hoover Dam

• Apportioned Colorado River water among the Lower Basin states: 2.8 MAF/year to Arizona; 4.4 MAF to California; 300,000 acre-feet to Nevada

1929
1929Colorado River History
California Limitation Act Enacted

California enacts the California Limitation Act, agreeing to limit its use of Colorado River water to 4.4 million acre feet per year.

June 25, 1929Colorado River History
Boulder Canyon Project Act in Effect

President Hoover declares the Boulder Canyon Project Act to be in effect.

1930
October 13, 1930Colorado River History
Suit filed by Arizona

Arizona files suit in the Supreme Court against the Secretary of the Interior and the other six basin states seeking to block implementation of the Boulder Canyon Project Act.

November 5, 1930Colorado River History
California asked to recommend apportionment for California users

Secretary of the Interior asks California to recommend an apportionment of its share of the Colorado River among water users in that state.

1931
May 18, 1931Colorado River History
Arizona’s action dismissed without prejudice

The U.S. Supreme Court dismisses Arizona’s action without prejudice, holding that the Boulder Canyon Project Act is a valid exercise of congressional authority and does not purport to abridge any of Arizona’s rights. Arizona v. California (I), 283 U.S. 423.

August 18, 1931Colorado River History
Relative priorities established by California Seven Party Agreement

California Seven Party Agreement among Palo Verde Irrigation District, Imperial Irrigation District, Coachella Valley County Water District, Metropolitan Water District of Southern California, City of Los Angeles, City of San Diego and County of San Diego establishes their relative priorities to Colorado River water.

September 28, 1931Colorado River History
Amended contract entered into by MWD

Metropolitan Water District of Southern California enters into an amended contract with the Secretary of the Interior for delivery of Colorado River water in accordance with the California Seven Party Agreement.

1932
December 1, 1932Colorado River History
Contract entered into by Imperial Irrigation District

Imperial Irrigation District enters into a contract with the Secretary of the Interior for delivery of Colorado River water in accordance with the California Seven Party Agreement. Contract also provides that the United States will construct Imperial Dam and the All-American Canal.

1933
February 7, 1933Colorado River History
Contract entered into by Palo Verde Irrigation District

Palo Verde Irrigation District enters into a contract with the Secretary of the Interior for delivery of Colorado River water in accordance with the California Seven Party Agreement.

February 15, 1933Colorado River History
Contract entered into by City of San Diego

City of San Diego enters into a contract with the Secretary of the Interior for delivery of Colorado River water in accordance with the California Seven Party Agreement.

1934
February 14, 1934Colorado River History
Arizona seeks to file a complaint in U.S. Supreme Court

Arizona seeks to file a complaint in the U.S. Supreme Court to perpetuate testimony for a future action arising out of the Boulder Canyon Project Act to be brought against California and others.

May 21, 1934Colorado River History
Arizona’s motion denied by Supreme Court

The Supreme Court denies Arizona’s motion.  Arizona v. California (II), 292 U.S. 341.

October 15, 1934Colorado River History
Contract entered into by Coachella Valley County Water District

Coachella Valley County Water District enters into a contract with the Secretary of the Interior for delivery of Colorado River water in accordance with the California Seven Party Agreement.

1935
October 1935Colorado River History
Arizona petitioned to file suit against California

Arizona petitions to file suit against California in the U.S. Supreme Court, seeking to quiet title to Arizona’s equitable share of the Colorado River and to limit California’s equitable share to no more than 4.4 maf. Arizona also asks for a decree that any other state’s use of Arizona’s equitable share of the Colorado River shall not constitute a prior appropriation or create any right superior to Arizona’s.

1936
May 25, 1936Colorado River History
Supreme Court again denies Arizona’s motion

Supreme Court again denies Arizona’s motion

1938
July 1, 1938Colorado River History
Parker Dam completed

Parker Dam is completed.

1938Colorado River History
Committee of Fourteen organized

The seven basin states organize the Committee of Fourteen, comprised of two representatives from each state, to address Colorado River issues.

1939
January 7, 1939Colorado River History
MWD diversions begin

Metropolitan Water District of Southern California begins diverting water through the Colorado River Aqueduct.

1944
January 3, 1944Colorado River History
Nevada enters into a contract

Nevada enters into a contract with the Secretary of the Interior for delivery of 300,000 af of Colorado River water.

February 3, 1944Colorado River History
1944 U.S.-Mexico Water Treaty

• Apportioned 1.5 MAF/year of Colorado River to Mexico during normal years and specified that Mexico would share proportionately in times of surplus and in reductions due to “extraordinary drought”

• Established the binational International Boundary and Water Commission to implement the Treaty

1944Colorado River History
Arizona ratifies the Colorado River Compact

Arizona ratifies the Colorado River Compact

1945
June 11, 1945Colorado River History
Supreme Court retreats from Wyoming v. Colorado ruling

The Supreme Court retreats somewhat from its ruling in Wyoming v. Colorado, holding that “strict adherence to the priority rule” when equitably apportioning the flow of a river among prior appropriation states “may not be possible.” While priority remains the “guiding principle,” the Court identifies a number of additional factors that may be taken into account. “For example, the economy of a region may have been established on the basis of junior appropriations. So far as possible those established uses should be protected though strict application of the priority rule might jeopardize them.”  Nebraska v. Wyoming, 325 U.S. 589, 618.

1947
1947Colorado River History
Arizona seeks legislation to authorize CAP

Arizona seeks legislation authorizing the CAP. California opposes.

1948 1950
February 21, 1950Colorado River History
Senate passes CAP legislation

Senate passes CAP legislation.

December 15, 1950Colorado River History
CAP legislation dies in House committee

CAP legislation dies in House committee.

1951
April 18, 1951Colorado River History
CAP legislation indefinitely postponed

House Committee on Interior and Insular Affairs indefinitely postpones action on CAP legislation “until such time as the use of the water in the Lower Colorado River Basin is either adjudicated, or a binding, mutual agreement as to the use of the water is reached by the states of the Lower Colorado River Basin.” (The Colorado River Board of California later boasted that it had been “instrumental” in achieving this result.)

June 5, 1951Colorado River History
Senate passes CAP legislation for the second time

Senate passes CAP legislation for the second time.

1952
August 13, 1952Colorado River History
Arizona files suit against California

Arizona files suit against California in Supreme Court to establish its right to Colorado River water.

1954
June 1, 1954Colorado River History
U.S. Supreme Court grants Nevada’s motion to intervene

U.S. Supreme Court grants Nevada’s motion to intervene in Arizona v. California (IV).

1955
December 12, 1955Colorado River History
U.S. Supreme Court denies California’s motion

U.S. Supreme Court denies California’s motion to join the four upper basin states in Arizona v. California (IV), but joins New Mexico and Utah as lower basin states.

1963
1963Colorado River History
Arizona v. California decision

U.S. Supreme Court decision in Arizona v. California

June 1963Colorado River History
California opposes authorization of Central Arizona Project

In reaction to the Supreme Court’s opinion, California immediately announces that it will oppose authorization of the Central Arizona Project.

1964
March 9, 1964Colorado River History
U.S. Supreme Court Decree: Arizona v. California

• After a decade of deliberation, the U.S. Supreme Court delivered its opinion in favor of Arizona, upholding its designated 2.8 MAF/year share of mainstream Colorado River water

• Effectively established the U.S. Secretary of the Interior as the Lower Basin “water master”

1965
1965Colorado River History
Western States Water Council established

Western governors establish the Western States Water Council to avoid interstate conflict by developing regional solutions to water problems

August 20, 1965Colorado River History
Basin states agree on four principles

Meeting in Washington, D.C., representatives of the seven basin states reach agreement on four general principles:

•The Lower Basin’s temporary use of unused Upper Basin water will not jeopardize Upper Basin rights.

•Importation of water from outside the Colorado River basin is essential and pending legislation should authorize construction of works to import at least 2.5 maf.

•Imported water should be available no later than 1980, although there appears to be sufficient water to meet all needs, including CAP, until the 1990s.

•Satisfaction of the Mexican treaty obligation should be a national obligation and the first priority for imported water.

1968
September 30, 1968Colorado River History
Colorado River Basin Project Act

• Authorized the Central Arizona Project –

• Authorized the Bureau of Reclamation to fund and construct the Central Arizona Project – learn more here

• Created a junior priority in the Lower Basin for CAP water and for any new Arizona contracts entered after 1968

• Directed the U.S. Secretary of the Interior to develop a plan for augmenting the Colorado River supply

1970 1973
1973Colorado River History
Minute 242 entered

U.S. and Mexico enter Minute 242 to the 1944 Treaty addressing salinity of water delivered to Mexico at Morelos Dam

1974
1974Colorado River History
Colorado River Basin Salinity Control Act passes

Colorado River Basin Salinity Control Act authorizes salinity control projects above and below Imperial Dam, including the Yuma Desalination Plant

1999
1999Colorado River History
Secretary of the Interior adopts regulations

Secretary of the Interior adopts regulations for offstream storage and release of unused apportionment enabling interstate water banking in the Lower Basin

2001
2001Colorado River History
Interim Surplus Guidelines adopted

Interim surplus determinations are suspended after California parties fail to complete a quantification settlement agreement by the December 31, 2002 deadline in the Interim Surplus Guidelines.

2003
January 1, 2003Colorado River History
Interim surplus determinations suspended

Interim surplus determinations are suspended after California parties fail to complete a quantification settlement agreement by the December 31, 2002 deadline in the Interim Surplus Guidelines.

October 10, 2003Colorado River History
Colorado River Water Delivery Agreement adopted

United States enters into Colorado River Water Delivery Agreement with Imperial Irrigation District, Coachella Valley Water District, Metropolitan Water District of Southern California and San Diego County Water Authority. The agreement memorialized the Secretary of the Interior’s commitment to deliver water to California contractors in accordance with the Quantification Settlement Agreement.

2003Colorado River History
Quantification Settlement Agreement executed

Quantification Settlement Agreement executed memorializing U.S. commitment to deliver water to California

2005
May 2, 2005Colorado River History
Efforts to develop conjunctive management guidelines begin

Secretary of the Interior announces her intent to develop guidelines for conjunctive management of Lakes Powell and Mead and shortage sharing in the Lower Basin by December 31, 2007, and initiates a public process toward that end. The Basin States are encouraged to reach agreement.

2006
February 3, 2006Colorado River History
Preliminary Proposal Regarding Colorado River Interim Operations submitted

Basin States submit a Preliminary Proposal Regarding Colorado River Interim Operations, including coordinated management of Lake Powell and Lake Mead and shortage guidelines for the lower basin.

2006Colorado River History
U.S. Supreme Court enters Consolidated Decree

U.S. Supreme Court enters its Consolidated Decree in Arizona v. California

2007
February 28, 2007Colorado River History
2007 Interim Guidelines

• Established a shortage framework for the Lower Basin

• Incentivized storage of water in Lake Mead through Intentionally Created Surplus (ICS)

Coordinated operations of Lake Powell and Lake Mead

• Expire in 2026

2012
2012Colorado River History
Minute 319 entered

U.S. and Mexico enter Minute 319 to the 1944 Treaty establishing criteria to share in water surpluses and shortages

2014
2014Colorado River History
Pulse flow released

Environmental pulse flow and base flow, allowed by Minute 319 to the 1944 Treaty, are released through the Colorado River channel in Mexico to start new vegetation for wildlife habitat

2019
April 16, 2019Colorado River History
Drought Continency Plan Authorization Act

Lower Basin highlights (learn more about Arizona’s implementation plan here):

   - Supplements the 2007 Interim Guidelines
   - Provides additional flexibility for the creation, storage and delivery of ICS
   - Created a “Tier Zero” at Lake Mead, requiring contributions to Lake Mead earlier, starting at elevation 1090’, and increased contributions at lower elevations
   - California agrees to make contributions to Lake Mead starting at elevation 1045’
   - Provided for the protection of Lake Mead elevation 1020’ – 500+ Plan

Upper Basin highlights:
   - Designed to minimize the risk of Lake Powell falling below elevation 3525’ and ensure compliance with the Colorado River Compact
   - Establish foundation for the storage of water in the Upper Basin as part of a demand management program that may be developed in the future

 

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