Series: Colorado Water Law Basics #14.2 - Colorado River Drought Contingency Plan
The 1922 Colorado River Compact split the river’s resources into two segments, the Upper Basin States (Colorado, Utah, Wyoming, and New Mexico) and the Lower Basin States (California, Arizona, and Nevada). The 1922 Compact allocated the “exclusive beneficial consumptive use of 7,500,000 acre-feet of water per annum” to each Division. However, the 1922 Compact did not establish apportionments of water within each Division. That apportionment was done at a later date, as described in last week’s blog. Unfortunately, the total apportionment to the Upper and Lower Basin States, 15 million acre-feet (MAF) annually, is more than the Colorado River yields. So how are the shortages dealt with equitably?
The issue of water shortages related to Compact entitlements has been known for some time as shortages became apparent in the early 2000s. As discussed in the LWS blog of May 4, interim guidelines related to how to deal with shortages in Colorado River supplies below the full allocation were initially put in place in December 2007, i.e., Colorado River Interim Guidelines.
Lake Mead
However, more extensive definition was required and, after many years of study and negotiations, the Drought Contingency Plan (DCP) was signed on March 19, 2019; this developed a voluntary means for both the Upper and Lower Basin States to conserve water to protect water levels in Lake Mead. Under the DCP, the Bureau of Reclamation (BOR) will make 24-month future projections of Colorado River yields based on inflow forecasts to assess the likely Lake Mead water level. This forecast provides the minimum, most, and maximum probable results of the forecast. Not only does the DCP forecasting seek to protect water supplies for the Lower Basin States but also the power production that the Western United States rely upon that is generated through hydropower at Lakes Powell and Mead. For example, approximately 4 billion kilowatts of power is generated annually at the Hoover Dam at Lake Mead, which is enough to serve approximately 1.3 million people for a year. Similarly, Glen Canyon Dam at Lake Powell generates approximately 5 billion kilowatts of power annually. Obviously, protecting continued power production at both dams is critically important.
With the implementation of the DCP, the Lower Basin States have agreed to leave 340 thousand-acre-feet (KAF) of their allocation in Lake Mead if the elevation in the lake is between 1,090 and 1,075 ft MSL (Tier 0). Tier 0 restrictions are were put into place by 2020, affecting Arizona’s and Nevada’s allocation, but not California’s allocation. Due to a 1963 Supreme Court decision in Arizona vs California, California’s allocation will not be reduced unless Lake Mead water levels drop below 1,045 ft MSL. Under Tier 0, Arizona has the largest reduction in allocation (192 KAF), while Nevada’s reduction is 8 KAF. Mexico also has to reduce its allocation by 41 KAF.
The trigger points for further allocation reductions are set at the Lake Mead elevations of 1,075 ft MSL (Tier 1), 1,050 ft MSL (Tier 2A), 1,045 ft MSL (Tier 2B), and 1,025 ft MSL (Tier 3). The DCP Tier 2 reduction is set at 1,050 ft MSL; however, because of the Supreme Court decision between California and Arizona there is no reduction in California’s allocation at the initiation of the Tier 2 level at 1,050 ft MSL but there is a reduction at 1,045 ft MSL (initially 200 KAF).
Based on the most recent future forecast by BOR it is expected that a Tier 1 drought level could be declared starting in 2022. What does this mean for the Lower Basin States? [Update: The U.S. Secretary of the Interior declared Tier 1 restrictions, effective January 1, 2022.] Under a Tier 1 restriction, Arizona’s allocation would be reduced by 512 KAF, while Nevada’s allocation would be reduced by 21 KAF and Mexico’s allocation would be reduced by 80 KAF. Again, as long as the projected elevation of Lake Mead is not projected to be at, or below, 1,045 ft MSL, California’s allocation will not be reduced. This would represent a total reduction of over 18% of Arizona’s allocation and 7% of Nevada’s allocation under the proportionate allocations set forth in the 1928 Boulder Canyon Project. Obviously, if current drought conditions continue in the Colorado River Basin, the BOR may be forced to implement even more drastic drought protection limits to maintain water levels in Lake Mead. Reductions could potentially reach levels that reduce Lower Basin State allocations by as much as 23% in Arizona, 8% in Nevada, and 7% in California, a total reduction of 1.1 MAF, as well as an additional reduction of 275 KAF to Mexico.
Lake Powell
These numbers are chilling for the Lower Basin States, but do the Upper Basin States have any obligations related to reduced water use under the DCP? The Upper Basin DCP aims to protect against Lake Powell reaching critically low elevations through coordinated Upper Basin reservoir operations. Under the Upper Basin DCP, the Upper Basin states agree to operate system units to keep the elevation of Lake Powell above 3,525 ft MSL, which is 35 ft above the minimum elevation needed to run the dam’s hydroelectric plant. Other large Upper Basin reservoirs (e.g., Navajo Reservoir, Blue Mesa Reservoir, and Flaming Gorge Reservoir) would be operated to protect the targeted Lake Powell elevation, potentially through drawdown of their own storage.
The Upper Basin DCP also authorizes storage of conserved water in the Upper Basin that would serve as the foundation for a water use reduction effort, i.e., a “Demand Management Program”. If established by the states, an Upper Basin DCP Demand Management Program would likely entail willing seller/buyer agreements allowing for temporary paid reductions in water use that would provide for more storage volume in Lake Powell. The demand management program contemplates there will be willing water users such as farmers, ranchers, industries, cities, and towns that would temporarily reduce their water consumption, thereby keeping more water in rivers and reservoirs. Water conserved through this program would be delivered to the Colorado River water “bank account” in Lake Powell.
The DCP has many complex conditions associated with its implementation. This is just a quick summary of some of the terms of the plan. However, if you are interested in learning more about the details of the DCP, there are a number of resources that can be found by clicking HERE.
If you have any water resources issues, LWS can help! For more information on this subject or any Western water rights issue, please contact us for help at 303-350-4090 or by email.
Bruce Lytle, P.E. bruce@lytlewater.com
Chris Fehn, P.E., P.G. chris@lytlewater.com
Anna Elgqvist, EI anna@lytlewater.com
