Shrinking Colorado River Reservoirs Highlight Need for Water-Use Efficiency, Supply Diversification

 
Short Title
Colorado River Reservoir Changes Won't Trim Water Deliveries
Reduced releases to Lake Mead in 2014 won’t trim water deliveries for San Diego County
Colorado River Reservoir Operations

The Bureau of Reclamation on Friday updated its “24-Month Study” of projected hydrologic conditions in the Colorado River Basin. Read the report here.

An unprecedented reduction in reservoir releases on the Colorado River announced Friday by the Bureau of Reclamation won’t cut water supplies to agencies in San Diego County or the rest of the Southwest during the 2014 “water year,” but the move does underscore the importance of continued conservation and water-supply diversification across the region.

The Colorado River is the most important water source for the Southwest, and it accounts for about 60 percent of San Diego County’s water supply. It’s under increasing pressure from a growing population in seven basin states and dry conditions for most of the past decade – particularly the past two years.

The river is managed by the Bureau, which on Friday said it expects to reduce releases from Lake Powell to Lake Mead by an estimated 750,000 acre-feet in the 2014 water year, which starts Oct. 1. The decision was triggered by projections that under standard operations Lake Powell would fall below elevation 3,575 feet. Changes announced Friday would make next year’s releases of 7.48 million acre-feet from Lake Powell the smallest since the 1960s. (An acre-foot is approximately 325,900 gallons, or roughly enough to serve two typical Southern California families of four for a year.)

Reducing releases from Lake Powell is among the management steps set in 2007 to minimize the impacts of dry periods on the river system. The changes planned for 2014 do not directly trigger shortage allocations for water users, though they do move the region closer to that possibility. If Lake Mead falls below elevation 1,075 – about 31 feet below where it is today – Arizona and Nevada would get less water from the Colorado River per the 2007 agreement. Current hydrological models show a very small likelihood of that occurring in the fall of 2014. If that were to happen, California still would receive its basic annual apportionment of 4.4 million acre-feet because of the state’s senior rights on the Colorado River.

“Shrinking reservoirs on the Colorado River reinforce the need to rethink water use in the Southwest,” said Halla Razak, Colorado River Program Director for the San Diego County Water Authority. “We will need innovation, collaboration and dedication to meet the challenges ahead."

A landmark 2012 report by the Bureau concluded that demands on the Colorado River could exceed supplies by more than 3.2 million acre-feet in 2060. The study said no single solution will suffice, and it outlines options for reducing the imbalances, such as additional conservation, extensive reuse and system augmentation.

“In San Diego County, we have been working hard for the past two decades to weather dry times by expanding reservoirs, diversifying water supply sources and promoting water conservation as a way of life, not just a response to emergencies,” Razak said. “Residents have embraced that ethic – and we all need to keep doing what we can to make sure that we use every drop as efficiently as possible."

Per capita water use in San Diego County dropped by about 30 percent between 2007 and 2012. The reductions resulted from water-use restrictions during the drought of 2008-11, the economic recession and widespread adoption of conservation strategies. Over the past decade, the Water Authority developed its $1.5 billion Emergency Storage Program, including the expansion of San Vicente Reservoir for use during dry years and emergencies. The Water Authority also has contracted to buy water from the drought-proof Carlsbad Desalination Project when it begins commercial production in 2016.

In addition, the Water Authority is an active participant in watershed planning for the Colorado River Basin. Razak said the agency will continue working with its state and federal partners, including Arizona and Nevada, to minimize the potential for shortage allocations.