Risk Management and Cutbacks on the Colorado The Colorado River is no longer operated as it was when the compact was signed in 1922. Between 2000 and 2019, more than 20 million acre-feet of water, or 60 percent of the system, disappeared, with most of that drop occurring between 2000 and 2004. Living with less water has led to a rapid series of changes in the Law of the River. The Colorado River Basin took its latest step in dealing with low flows, declining reservoir levels, and a changing climate in 2019, when the basin states, Bureau of Reclamation, and Interior Department adopted the Drought Contingency Plan, and with that action, activated the Binational Water Scarcity Contingency Plan. The plans, layered on the
existing 2007 interim guidelines, look to hedge risk by reducing some dependence on the Colorado River. The upper basin will be able to operate its reservoirs to maintain water levels in Lake Powell while exploring the possibility of developing a demand management program. It will also continue water augmentation activities like cloud seeding, and will continue “equalizing” the contents of lakes Powell and Mead, per the interim guidelines, but with a 500,000 acre-foot drought pool that would be exempted from the re-balancing. Under the interim guidelines, releases out of Powell are prescribed based on water levels in both Powell
and Mead, to balance the reservoirs and the risk of shortage. For the lower basin, the DCP, interim guidelines, and the Binational Water Scarcity Contingency Plan lay out cuts in water deliveries from the Colorado River, triggered by projections of Lake Mead storage elevations. While the interim guidelines already dictated cuts, beginning with Mead reaching 1,075 feet above sea level, the DCP created a new “tier zero” at 1,090 feet and added additional cuts for the lower basin states and Mexico to absorb. The greatest cuts to lower basin water use will come from Arizona and California, but all states and Mexico will share in scarcity.
Lake Mead Delivery Reductions for 2007 Interim Guidelines and Drought Contingency Plans ARIZONA Interim Guidelines and DCP
NEVADA Interim Guidelines and DCP
MEXICO MIN 323 and Water Scarcity Contingency Plan
CALIFORNIA DCP
Lake Mead storage elevations 1,075'–1,090'
192 8 41
Tier Zero
1,050'–1,075'
512 21
80
Shortage conditions
1,045'–1,050'
592 25
1,040'–1,045'
640
27
1,035'–1,040'
640
27
154
1,030'–1,035'
640
27
162
1,025'–1,030'
640
27
104
720
Less than 1,025' 0 In thousands of acre-feet
300
146
200 250
Inactive pool 300
171
350
30
600
275
350
900
1,200
The Law of the River and Lake Powell and Lake Mead Combined Storage 60
1970
Long Range Operating Criteria
Reservoir storage in millions of acre-feet
Combined maximum capacity
50
1974
1968
Colorado River Basin Project Act
40
1948
Upper Colorado River Basin Compact
1944
Colorado River Basin Salinity Control Act
1964
1956
Consolidated Supreme Court Decree, Arizona v. California
Colorado River Storage Project Act
U.S.-Mexico Water Treaty
30
20
10
1922
Colorado River Compact
1928
0 1937
Boulder Canyon Project Act
1947
12 • W A T E R E D U C A T I O N C O L O R A D O
1957
1967
1977
