Drought Contingency Plans for the Colorado River Basin

INSIGHTi Drought Contingency Plans for the Colorado River Basin Updated February 15, 2019 The Colorado River Basin is a critical source of water and power supplies for seven western states and Mexico. The basin is in the midst of a long-term drought, and water levels at its. Water levels at the basin’s two largest reservoirs, Lake Mead and Lake Powell, could reach critically low levels. Building on several prior agreements, the basin states and the Bureau of Reclamation (Reclamation) recently announced Drought Contingency Plansdrought contingency plans (DCPs) that aim to decrease the likelihood of major water and power supply curtailments for users.

Colorado River Basin in Context

The Colorado River Basin (Figure 1) covers approximately 246,000 square miles, 97% of which are in the United States. It includes the Colorado River and its tributaries, which cross the U.S. border into Mexico before discharging into the Gulf of California. Pursuant to federal law, multiple federal facilities (e.g., Hoover Dam and Glen Canyon Dam) store and convey water from the river and its tributaries and generate hydropower for the southwestern United States. The primary federal agency with jurisdiction over the river is Reclamation, an agency within the Department of the Interior (DOI).

Figure 1. Colorado River Basin and Major Facilities

Congressional Research Service https://crsreports.congress.gov IN10984 CRS INSIGHT Prepared for Members and Committees of Congress Congressional Research Service Figure 1. Colorado River Basin and Major Facilities Source: Bureau of Reclamation.

. Based on observed data, average natural Colorado River flows in the 20^th centuryflows in the 20th century were about 15 million acre-feet (maf) annually. Flows have dipped during an ongoing, long-term drought dating from 2000; Reclamation estimated that from 2008 to 2018, flows averaged 12.9 maf. 2 Congressional Research Service acre-feet (maf) annually, while paleoclimate reconstructions estimated that mean annual flows were lower (ranging from 13-14.7 maf). Flows have dipped during the ongoing drought; Reclamation estimated that from 2000 to 2016, flows averaged 12.4 maf. These lower flows appear to parallel historic droughts on the river, some of which lasted for decades.

Colorado River Compact The Colorado River Compact of 1922, negotiated, agreed to by the basin states and the federal government, is the foundation of the "“Law of the River,"” which governs Colorado River operationswater management. Under the compact, the states established a framework to apportion the water supplieswater supplies are divided equally between the Upper Basin and the Lower Basin, with the dividing line at Lee' Lee’s Ferry, AZ (near the Utah Border). Each basin was apportioned 7.5 maf annually. Congress approved the compact in the Boulder Canyon Project Act of 1928. Multiple other compacts, federal laws, court decisions, and regulatory guidelines have since been added to the Law of the River. State-level apportionments were established by documents approved subsequent to the Colorado River Compact of 1922 (Figure 2). . Pursuant to a 1944 treaty with Mexico, an additional 1.5 maf per year was reserved for flows south of the border.

Figure 2. U.S. Colorado River Apportionments by State

Sources: Colorado Riverto Mexico. Figure 2. U.S. Colorado River Apportionments by State Sources: Colorado River Compact of 1922, Boulder Canyon Project Act (43 U.S.C. 617), and the Upper Colorado River Basin Compact of 1948. Notes: Assumes Colorado River Compact apportionment of 15 maf (7.5 maf to each basin). Does not reflect tribal diversion rights and 1.5 maf to 1.5 maf to Mexico under the Mexican Water Treaty of 1944. Supply/Demand Imbalance Consumptive use in the basin typically exceeds natural flows, and studies project this trend will lead to a long-term imbalance in basin supply and demand. The basin has thus far avoided major impacts on supplies due in large part to its significant storage (60 maf), coupled with the fact that Upper Basin states have not fully developed their entitlement. However, less water is in storage as a result of the drought. Additional supply/demand imbalance could result from projected population increases and the development of tribal water rights, among other things. 3 Congressional Research Service 4 Drought Contingency Plans In October 2018, after several years of negotiations, draft DCPs were announced for the Upper and Lower Basins. The DCPs aim to decrease the likelihood of major supply curtailments and other basin impacts. They build on a series of prior agreements  2003 Mexico under the Mexican Water Treaty of 1944.

• 2003 Quantification Settlement Agreement (QSA). The QSA aimed to have California (QSA). California agreed to reduce water use to adhere to its Colorado River water allocation, while also committing the state and committed to a path for restoration of the Salton Sea (a related water body in Southern California).
• .  2007 Colorado River Interim Guidelines for Lower Basin Shortages and the Coordinated Operations Coordinated Operations for Lake Powell and Lake Mead.. These guidelines included criteria for "balancing"“balancing” releases from Lakes Mead and Powell determined by "trigger levels" at both reservoirs, a schedule of Lower Basin curtailments, and a mechanism for storing and delivering conserved water in Lake Mead.
• 2014 and a mechanism for storing conserved water in Lake Mead. They also included a schedule of Lower Basin curtailments in Arizona and Nevada if Lake Mead drops to an elevation of 1,075 feet or less (i.e., a “shortage condition”). As of January 2019, there was a 69% chance of a shortage condition beginning in 2020. 2014 Pilot System Conservation Program.Pilot System Conservation Program. This DOI-led effort provided cost-shared funding for projects to conserve water supplies in the Lower Basin.
• 2017 Minute 323 Agreementagreement with Mexico.. This agreement extended and replaced the previous Minute 319 agreement (2012) and, among other things,with Mexico. It included increased U.S. storage opportunities for Mexico and a Binational Water Scarcity Planbinational plan that would commit Mexico to tiered cutbacksnew delivery curtailments parallel to those in the Lower Basin DCP (see below).

.   The Upper Basin DCP would establish a Demand Management Program for the Upper Basin by authorizing storage of conserved water in Lake Powell. It also would establish 3,525 feet as the target operational level for Lake Powell. Together, these efforts would decrease the risk of Lake Powell's ’s elevation falling below 3,490 feet, at which point reduced hydropower generation and cutbacks to water users are possible.

The Lower Basin DCP would require that when Lake Mead reaches predetermined elevations, Lower Basin states would forgo deliveries beyond previously agreed-upon levels. It also wouldwould further incentivize voluntary conservation of water to be stored in Lake Mead and commit DOI to conserving 100,000 acre-feetacrefeet of water that will be left in the system. The agreement's aim is aims to avoid Lake Mead elevations falling below 1,020 feet. DCP implementation requires approval by basin states and stakeholders of the DCPs and a number of related intrastate agreements. Federal actions in the DCPs also require authorization by Congress. On February 1, 2019, Reclamation Commissioner Brenda Burman announced that basin states had not completed all of the required steps to approve the DCPs by a previously established January 31 deadline. Thus, the bureau published a Federal Register notice requesting input from basin state governors regarding how DOI might reduce the risk of drought in the basin. If the DCPs are completed by March 19, the notice would be rescinded and the DCPs could be finalized with congressional authorization. If they are not completed, DOI may use its authority to make unilateral water delivery cutbacks in the basin. Congressional Research Service 5 Author Information Charles V. Stern Specialist in Natural Resources Policy Disclaimer This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan shared staff to congressional committees and Members of Congress. It operates solely at the behest of and under the direction of Congress. Information in a CRS Report should not be relied upon for purposes other than public understanding of information that has been provided by CRS to Members of Congress in connection with CRS’s institutional role. CRS Reports, as a work of the United States Government, are not subject to copyright protection in the United States. Any CRS Report may be reproduced and distributed in its entirety without permission from CRS. However, as a CRS Report may include copyrighted images or material from a third party, you may need to obtain the permission of the copyright holder if you wish to copy or otherwise use copyrighted material. IN10984 · VERSION 7 · UPDATED below 1,020 feet.