Temporary Barrier Will Deter Saltwater and Protect Delta Water Quality
SACRAMENTO REGION, CA (MPG) – The Department of Water Resources (DWR) has begun construction on a temporary emergency drought barrier on West False River in the Sacramento-San Joaquin Delta after receipt of all necessary state and federal permits for the project. The barrier will help block saltwater from flowing into the central Delta and contaminating water supplies for millions of Californians during a fourth consecutive summer of drought.
“California’s four-year drought is one of the worst in our recorded history,” said DWR Director Mark Cowin. “With 2015 turning out to be warmer and drier than normal, water conservation is crucially important. The rock barrier in the Delta is an undesirable but necessary tool for freshwater conservation.”
State and federal water and wildlife officials, working as a real-time drought operations management team, determined that the barrier will help deter the tidal push of saltwater from San Francisco Bay into the central Delta. The approximately 750-foot-wide barrier—essentially a pile of rocks with a 48-inch pipe embedded within it parallel to the river’s flow—will span the river but still allow limited water flow upstream and downstream, depending upon tides.
Keeping saltwater from the central Delta is a priority, as a large portion of the state’s fresh water for urban and agricultural use goes through this part of the Delta. The barrier would help prevent saltwater contamination of water supplies used by 25 million people who rely on the Delta-based federal and state water projects for at least some of their supplies, including residents of the Delta and Contra Costa, Alameda, and Santa Clara counties.
Typically, when saltwater threatens to encroach deeper into the Delta, water project operators repel it either by slowing the pumping of water from the Delta or increasing the amount of water flowing into the Delta from upstream reservoirs.
In this fourth year of drought, Delta pumping by the state and federal water projects is already negligible, and it takes three to five days for fresh water released from Lake Oroville or Shasta Lake to reach the Delta. An emergency barrier will provide an additional tool to help limit salinity intrusion should high winds or another unexpected event push salt farther west than expected this summer.
The emergency barrier will also help mitigate a worst-case circumstance this summer in which upstream reservoirs lack sufficient water to meet the minimum outflow requirements to limit Delta salinity intrusion.
The last of the permits were received earlier this week. In addition to a levee modification permit from the U.S. Army Corps of Engineers and a California Endangered Species Act permit from the California Department of Fish and Wildlife, DWR sought and received a Temporary Urgency Change Permit renewal from the State Water Resources Control Board.
In addition, DWR must consult with the U.S. Fish and Wildlife Service and National Marine Fisheries Service on protections for Delta smelt, Chinook salmon and other listed species. All of these agencies have worked cooperatively on the real-time drought operations management team for the past year.
In May, with permits in hand, DWR authorized the Dutra Group of San Rafael to begin construction at the site, 0.4 miles from where West False River flows into the San Joaquin River. Installation lasted several weeks using basketball-sized rocks transported by barge to the barrier’s location between Bradford and Jersey islands. The barrier will be removed by mid-November.
The trapezoid-shaped barrier, about 12 feet wide at the top, will block boat passage on West False River until its removal and will be marked by warning signs, lights, and buoys. DWR notified marinas and individuals in the Delta about these restrictions. Alternative routes between the San Joaquin River and interior Delta, including Bethel Island marinas, are available.
Emergency barrier removal will finish no later than mid-November to avoid the traditional flood season and potential harm to migratory fish. Removal is expected to take 45 to 60 days.
Design, installation, monitoring, mitigation, and removal are estimated to cost roughly $22 million; the cost for removal is set at $18 million. Costs are to be paid with a mix of funding from Proposition 50, a $3.4 billion water bond approved by voters in November 2002, and General Fund dollars.
Earlier Consideration of Emergency Barriers
The West False River site raises fewer concerns for threatened and endangered fish than other potential barrier sites considered by DWR. Last year, DWR studied the potential impacts of temporary barriers at three locations: Steamboat Slough, Sutter Slough, and West False River. The analysis found anticipated impacts could be mitigated to a less-than-significant level. DWR received and reviewed considerable public comments on the Initial Study and Proposed Mitigated Negative Declaration. DWR is not pursuing installation of temporary emergency barriers at Sutter Slough or Steamboat Slough in 2015.
The April 1st, 2015 Executive Order by Governor Brown helped expedite installation of the West False River barrier in time to address emergency drought conditions this year. DWR last used emergency drought barriers to reduce salinity intrusion in 1976-77. DWR considered the installation of emergency drought barriers in 2014 but determined in late May of last year that they would not be needed, in part because February and March storms improved water supply conditions. Planning for future emergency drought barriers continued after last year’s decision, with a focus on West False River, Steamboat Slough, and Sutter Slough.
Earlier this year, based on the input of Delta residents, the Department also considered the feasibility and effectiveness of barriers on Miner Slough in the western Delta and on Steamboat Slough downstream of its confluence with Sutter Slough.
Emergency drought barriers on Miner Slough and Steamboat Sloughs were eliminated from consideration because of U.S. Fish and Wildlife Service concerns about potential effects on threatened Delta smelt.
Current Drought Emergency
The three-year period from 2012 through 2014 was the driest three-year period on record in California, and 2015 opened with the driest January in the state’s recorded history. The Sierra Nevada snowpack typically peaks by April 1st; this year, the snowpack was measured at five percent of historic average on April 1st, the lowest measurement in recorded history.
Governor Brown declared a drought State of Emergency on January 17th, 2014 and directed state officials to take all necessary actions to prepare for water shortages. The State Water Resources Control Board on March 17th, 2015 announced new restrictions on water use, including limiting outdoor watering to two days per week and prohibiting lawn watering during rainfall and during the next two days.
In April, Governor Brown directed the State Water Board to implement mandatory water reductions in cities and towns across California to reduce water usage by 25%. On May 5th, the State Water Board established water conservation standards for communities throughout the state, ranging from a low of 4% to 36% as compared with the community’s 2013 water use and depending on per capita water use in each community.
To learn about all the actions the state has taken to manage our water system and cope with the impacts of the drought, visit Drought.CA.Gov. Every Californian should take steps to conserve water. Find out how at SaveOurWater.com.
Source: California Department of Water Resources