Grassland Bypass Project
The California Regional Water Quality Control Board, Central Valley Region, issued a Waste Discharge Requirement (WDR) that specified the maximum monthly and annual loads of selenium that the Project may discharge into Mud Slough and the San Joaquin River . The WDR includes monthly monitoring for molybdenum and nutrients (nitrate, ammonia, total Kjedahl nitrogen, total phosphate, and ortho-phosphate); weekly analyses of salinity, selenium, boron, and other parameters, and chronic toxicity testing. The WDR also outlines a program to monitor storm water releases from the Grassland Drainage Area into the Grassland wetland supply channels should they occur.
The Use Agreement between Reclamation and the Authority specifies the conditions for use of the San Luis Drain for the Project, and further specifies the maximum monthly and annual loads of salt that can be discharged by the Project.
Data from the Project’s monitoring program are collected and reviewed by staff from the U.S. Fish and Wildlife Service, Environmental Protection Agency, Central Valley Regional Water Quality Control Board, California Department of Fish and Game. The data are published by the San Francisco Estuary Institute. Monthly data reports and annual reports are available on the Institute’s web site.
Since implementation of the Project, all discharges of drainage water from the Grassland Drainage Area into wetlands and refuges have been eliminated. The Project has reduced the load of selenium discharged from the Grassland Drainage Area by 61percent (from 9,600 lbs to 3,700 lbs). The load of salts has been reduced by 39 percent (from 187,300 tons to 113,600 tons).
Prior to the Project, the monthly mean concentration of selenium in Salt Slough was 16 parts per billion. Since October 1996, the concentration has been less than the water quality objective of 2 parts per billion.
For more information, contact:
M. Chris Eacock
(for the San Luis & Delta Mendota Water Authority)
Summers Engineering, Inc.
PO Box 1122
Hanford, CA 93232
559/582-9237 | FAX 559/582-7632
June 8, 2015
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