Here’s a guest column from Bruce Babbit that’s running on AZCentral.com:
It’s too soon to tinker with key parts of the Colorado River Compact. For now, our best bet may be to temporarily extend the Drought Contingency Plan.
Lake Mead is disappearing. It has already fallen more than 146 feet since 2000.
Last week the Bureau of Reclamation forecast that it will likely drop another 42 feet in the next five years, drawing the lake surface down to a level barely sufficient to generate power and release water for downstream water users in California and Arizona.
To manage this decline and stabilize the lake is not rocket science. Cities and farms are simply taking more water out of Lake Mead than is coming in from the Colorado River. The lake is like a bank account: on average, you can only take out as much as is being deposited by the Colorado River.
We’ll need all of DCP’s cuts to stabilize Lake Mead
When the current drought began in 2000, the three Lower Basin states that take water from the lake (Arizona, California and Nevada) suddenly awakened to the problem. After several years of difficult negotiations, they agreed on a Drought Contingency Plan (DCP) that, with previously agreed cuts, would bring the lake into balance.
Hoping the drought would lift before too long, the DCP negotiators agreed to spread the cuts over coming years in response to changing lake levels. However, as the drought continues and intensifies, the Drought Contingency Plan is looking more like a Drought Certainty Plan.
It now appears that the full schedule of DCP reductions will be needed to bring the lake into balance at approximately 1,025 feet of elevation. The next reduction begins in 2022, a further cut is likely in 2023 with even deeper remaining cuts likely to occur by 2026, the year in which the current DCP will expire.
By that time the states that share the Colorado River must reach a new agreement. Their first task will be to decide whether still more reductions beyond the present DCP will be necessary in a new “DCP Plus.” It will be a close call, for the existing DCP schedule may be enough to bring the lake into balance, albeit at a very low level.
The negotiators will then face a newly emerging problem – the threat that the Colorado River might run so low, there will not be enough inflow to stabilize the lake, even with the full agenda of DCP reductions.
It works if we keep getting the minimum flow
So far Arizona and the Lower Basin states have managed through the drought by counting on a steady average minimum of at least 7.5 million acre feet of new water released annually from upstream reservoirs into Lake Mead. This minimum flow “guarantee” is contained in Article III(d) of the Colorado River Compact, the basic law governing the river.
This combination of a guaranteed minimum inflow from upstream reservoirs, paired with scheduled DCP reductions, makes it possible to plan with some confidence for Central Arizona Project (CAP) deliveries.
The Central Arizona Project aqueduct will not run dry and disappear alongside the ancient Hohokam canals. It will continue to deliver water up from the river to the Phoenix and Tucson areas.x
As long as the scheduled DCP cuts are carried out, and as long as the minimum anticipated inflow guaranteed by Article III(d) remains in place, the CAP should deliver into the future an average of about 40% less than the delivery forecast in 2020.
As its shoreline shrinks, Lake Mead will be a smaller lake, but it should hold steady at a level sufficient to generate power and deliver water through its outlets. And it will remain a beautiful and inviting National Recreation Area.
A warming climate could upend the law of the river
However, there is an elephant in the room. It is called human caused global warming.
As the climate continues to warm, rising temperatures cause more of the runoff from rain and melting snow to both evaporate and soak into drying soils before reaching the Colorado River.
Scientists predict that as the climate continues to warm, river flows could continue to decline by as much as 20% to 30% by 2050.
If these predictions hold, there will come a point at which the guaranteed Article III(d) flows into Lake Mead could so severely limit water use in the Upper Basin states of Colorado, Utah, New Mexico and Wyoming that the entire law of the river, including the Colorado River Compact, will be up for discussion and reconsideration.
We have not reached that point.
More studies are necessary and the predictive power of science is still evolving. The natural drought cycle that exists apart from global warming may lift. The Upper Basin states have yet to curtail any of their water uses in order to send flows to the Lower Basin.
For now, it might be smart to extend DCP
It is, therefore, too soon to be tinkering with Article III(d) or other provisions of the Colorado River Compact.
From the vantage point of today, the best alternative for a new agreement in 2026 will be to extend the existing DCP for another 10 years.
The negotiators will surely need to make adjustments to the amount and timing of DCP reductions. And there is certainly some flexibility to simultaneously adjust the amount and timing of the Upper Basin’s releases to the Lower Basin.
The Colorado River is a magnificent and wildly unpredictable resource. Managing it will always require our ongoing vigilance and commitment to working together to create fair and equitable outcomes.
Bruce Babbitt is is a former Arizona governor and former U.S. Secretary of the Interior. Reach him at firstname.lastname@example.org.