Fact Sheet: Colorado River Drought Contingency Plans by Water Education Colorado

OCTOBER 2021

FACT SHEET

Colorado River Drought Contingency Plans Amid a multi-decadal drought, inflows and reservoir levels in the Colorado River Basin have plunged to neverbefore-seen lows. That’s why Colorado River Basin states along with the U.S. Bureau of Reclamation and the Department of the Interior adopted Drought Contingency Plans (DCPs) in 2019. The plans — one for the upper basin and one for the lower basin — aim to hedge risk by reducing some dependence on the Colorado River. Those DCPs are temporary and expire in 2026, along with the 2007 Interim Guidelines for Lower Basin Shortages and the Coordinated Operations of Lake Powell and Lake Mead. Compact Compliance for the Upper Basin Under the 1922 Colorado River Compact, the upper basin states and lower basin states are, theoretically, each given rights to half of the river’s flow, or 7.5 million acre-feet per year on average. The upper basin, however, must not deplete the flow of the river at Lee Ferry, downstream of Lake Powell, below 75 million acre-feet in a 10-year period. Lake Powell is used as a reserve supply to manage releases and mitigate low-flow years. Because of this non-depletion requirement, regardless of inflows, the upper basin takes on a large burden when coping with declining flows. It is possible the upper basin would have to reduce its water use in order to comply with the compact. Compliance with the compact allows the upper basin to maintain some control over its water supply.

Colorado continues to study Lake Powell drought pool feasibility

Colorado’s contribution to the seven-state Colorado River Basin system derives from the flows of the Yampa, White, Gunnison, San Juan and Dolores rivers, as well as the Colorado River itself. In wet years, the river and its tributaries can generate more than 13 million acre-feet of water. But in dry years, they generate just 5.2 million acre-feet. A groundbreaking effort to create a new upper basin drought pool could store up to 500,000 acre-feet of water, with likely just over half coming from Colorado.

The Upper Basin Drought Contingency Plan When the upper basin passed its Drought Contingency Plan (DCP), it aimed to operate its reservoirs to maintain water levels in Lake Powell while exploring the idea of developing a program to cut water use. At the time, reservoir levels weren’t critically low so the plan was banking on taking the time to discuss and test the best way to reduce reliance on the river. The upper basin’s DCP lays out three elements: 1. Exploring demand management and, if a program is established, conserved water can be stored in a 500,000 acre-foot drought pool in Lake Powell to be used only for upper basin compact compliance;

2. Drought operation of the Colorado River Basin Storage Project reservoirs — Flaming Gorge, the Aspinall Unit, and Navajo — to release significant volumes of water to improve storage levels in Lake Powell; and

3. Continued water augmentation activities, including weather modification, such as cloud seeding.

What is demand management? Demand management in this context is conservation on such a large scale that it reduces the amount of water drawn from the Colorado River in a significant, measurable way. If the upper basin states are able to develop a demand management program, reductions in consumptive use of Colorado River Basin water are envisioned to be temporary, voluntary and compensated. The aim of the program would be for the upper basin states to collectively use less water, then track, deliver and bank those savings, setting aside up to 500,000 acre-feet of water in a special, protected Lake Powell drought pool. The pool would provide additional insurance for the upper basin to prevent them from losing access to river water if they were to fail to meet their obligations 2.4% to Arizona, Nevada and California. 7.8%

through workshops, workgroups, listening sessions and more, coordinated by the Colorado Water Conservation Board (CWCB). It remains an open-ended investigation. A number of questions linger about how demand management should be structured, how conserved water would be tracked and protected en route to storage, how water rights holders who forego use would be paid, how unintended consequences could be avoided, and whether this is the best strategy and tool at this point in time.

The Lower Basin Drought Contingency Plan

The lower basin’s plan lays out cuts in water deliveries from the Colorado River, triggered by projections of Lake Mead storage elevations. While the1.3% 2007 interim guidelines already Yampa 6.2% cuts, beginning with Mead reaching dictated 19.8% 19.1% 1,075 feet10.1% above sea level, theWhite DCP created a new “tier zero” at 1,090 feet and added What’s the status of a demand Colorado—In Basin 6.1% 26.4% additional cuts for the lower basin states and management program? Colorado—TMD* Mexico to absorb. The greatest cuts to lower Each21.8% of the upper Colorado River Basin states basin water use will come from Arizona and is conducting its own feasibility investigation Gunnison California, but all three lower basin states and and, in order to 21.8% implement a demand 57.1% Mexico will share in scarcity. Southwest The lower basin management program, the entire upper basin is already taking tier zero cuts under the DCP. must agree to it. Additional, more significant cuts will be enacted In Colorado, that feasibility work has been in 2022. moving forward over the past two years

Who’s Water is at Risk in Colorado?

Within Colorado, water users rely heavily on Colorado River water, averaging just over 2.5 million acre-feet of consumptive use per year statewide. If Colorado and the other upper basin states were forced to cut back to comply with the 1922 Colorado River Compact, post-1922 water rights, those established after the compact was settled, risk curtailment. When Colorado’s total Colorado River use is compared against that with post-1922 rights, 96% of transmountain diversions, where water is piped from the Colorado River to a different basin, such as the South Platte or Arkansas, are at risk, while 30% of Colorado River diversions on the Yampa are at risk, 19% on the White, 14% on the Colorado mainstem, 10% on the Gunnison, and 36% in the Southwest Basin. Average Annual Colorado River Depletions by Basin

800 thousand acre-feet

600

551.1

531.9

551.1

196.9

Yampa

* Transmountain Diversions

62.0

178.2

92.3

57.3

11.9

White

The previous low-level record at Lake Powell, which it hit in 2005.

3,525 and 3,490 feet Critical levels at Lake Powell. 3,525 feet represents a low-level balancing tier in the 2007 interim guidelines, but it also indicates that the reservoir is holding just 2 million acre-feet of water above “minimum power pool,” or 3,490 feet, which is the level at which the reservoir can generate little or no hydropower.

500,000 acre-feet The amount of conserved water that could be stored in upper Colorado River reservoirs if the upper basin establishes a demand management program.

2.5 million acre-feet The amount of Colorado River water depleted annually on average by Colorado water users between 1988–2005. Sources: U.S. Bureau of Reclamation; Upper Colorado River Colorado River Risk Study Phase III

RESOURCES

Colorado Water Conservation Board’s Demand Management Feasibility Investigation https://bit.ly/3o9KF2v

500.7

400

58.4

3,555.1 feet

Upper Colorado River Commission https://bit.ly/39F6miL

669.2

2021

The year water levels in Lake Powell hit record lows — as of September 2021, the water level at Powell stood at 3,547 feet. The reservoir hasn’t been this low since it filled more than 50 years ago.

Colorado River Basin Drought Contingency Plans https://on.doi.gov/3CPH8un

Average Post-compact Depletions

200

BY THE NUMBERS

Colorado In Basin

Colorado TMD*

Gunnison

Southwest

Source: Colorado River Risk Study Phase III

Contingency Plan, Fall 2019 issue, Headwaters magazine https://bit.ly/3mlx7P3 Colorado River Risk Study Phase III https://bit.ly/3AT0SwQ

Produced by Water Education Colorado, an independent and nonpartisan nonprofit working to ensure Coloradans are informed on water issues, in collaboration with its news initiative, Fresh Water News.