October through March marks California’s rainy season. With more than 19 inches of rainfall already registered, Orange County is well above its normal 14 inches for the year, however, the drought is not officially over. In February, the State Water Resources Control Board (SWRCB) extended its existing water conservation regulations, which prohibit wasteful practices and set a conservation mandate for water suppliers without enough water reserves to withstand three more dry years.
The board cited California’s variable weather patterns and the stressed groundwater basins, which will require several years of above average rainfall to rebound to normal levels as reasons for continuing the conservation regulations. The board agreed to re-evaluate the situation in May rather than terminate the existing regulations put into place due to the drought.
It will take about two to three above average rainfall years for the Orange County Groundwater Basin to refill, but we can still live comfortably, without pumping restrictions in the meantime. One reason is added Santa Ana River stormwater capture. Except for required flood control releases, OCWD has been able to capture 100 percent of Prado Dam release flows since it began raining in November 2016 and has put the water back into the Orange County Groundwater Basin. This additional stormwater capture is due to temporary modifications in the operation of Prado Dam by the U.S. Army Corps of Engineers to allow water conservation (formerly 498 feet) up to elevation 505 feet above mean sea level.
The temporary modifications to Prado Dam’s operations by the Corps, referred to as deviations, allowed capture of an additional 22,275 acre-feet of stormwater through March 23. That’s enough water for 178,200 people for a year. Further rainfall events would allow even greater amounts of stormwater capture.
The capture of stormwater and its recharge into the groundwater basin is the most economical way to replenish local water supplies and one of the most efficient. Maximizing the use of local water resources helps sustain future pumping from the basin.
The Orange County Water District appreciates its long and productive relationship with the USACE. This relationship has provided for notable successes in managing water resources in the Santa Ana River Watershed in Southern California.
The District and the Corps are currently working on a long-term plan called the Prado Feasibility Study that, if successful, could lead to permanently changing the Prado Dam Water Control Manual to allow water conservation up to 505 feet amsl year-round.
The District values the leadership of the USACE and looks forward to continued collaboration to refill the Orange County Groundwater Basin to bring it back to healthy pre-drought levels.
The groundwater basin is only about 37 percent full, but OCWD is confident that with this season’s stormwater capture and natural recharge from recent rains, the 100 million gallons per day of Groundwater Replenishment System “new” water, and the availability of imported water, will make significant progress in refilling the basin.
The above average rainfall has certainly improved the local water supply conditions, but groundwater levels are still below target elevations and the District has to continue to be vigilant in managing the groundwater basin.
If you’d like an in-depth look at water in our region presented by recognized experts, I invite you to sign up for the OC Water Summit (http://www.ocwatersummit.com/) in Anaheim on June 16 at the Grand Californian Hotel in the Disneyland Resort.
–James Vanderbilt represents Division 9 of the Orange County Water District and is Mayor Pro Tempore of Anaheim.
This article appeared in the April 19, 2017 print edition of the News Enterprise.
