esm223 20 Reading - TMDL Final Staff_Report 23Oct06

esm223 20 Reading - TMDL Final Staff_Report 23Oct06 - UPPER...

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Staff Report: Upper Santa Clara River Chloride TMDL Reconsideration 2 Executive Summary The Upper Santa Clara River (USCR) Chloride Total Maximum Daily Load (TMDL) became effective on May 5, 2005. The TMDL includes special studies to determine the chloride threshold for salt-sensitive crops and the chloride loading from surface water to underlying groundwater basins. The TMDL also includes Los Angeles Regional Water Quality Control Board (Regional Board) reconsideration of the TMDL schedule 12 months after the TMDL effective date based on results of the special studies. This Staff Report summarizes background information on chloride issues and the current status and results of TMDL-related activities in the USCR. It provides four alternatives for revising the TMDL Implementation Plan schedule for Regional Board consideration and staff’s recommended alternative. Regional Board staff finds that the work to date provides critical information on the chloride hazard concentration for salt-sensitive crops. Completion of the first Special Study, the Literature Review and Evaluation (LRE), provided a scientifically defensible baseline to support a Water Quality Objective (WQO) that is protective of agricultural supply beneficial use (AGR). The LRE established a chloride guideline concentration of 100-117 milligrams per liter. The chloride guideline concentration established by the LRE may be further refined through extended agricultural studies, which may take decades to complete. The status of additional TMDL studies, including the groundwater surface water interaction (GSWI) study, the cost study for advanced treatment to reduce chloride loadings through reverse osmosis and brine disposal, and Endangered Species Protection (ESP) study are described in this Staff Report. The TMDL provides a thirteen-year schedule to attain compliance with the WQO for chloride. Based on the results of TMDL studies to date, staff developed four alternatives for Regional Board consideration, including: a no-action alternative in which the Regional Board takes no action to revise the schedule at this time; an alternative that adds implementation milestones in years 6-13 of the TMDL schedule but neither extends nor accelerates the 13-year TMDL implementation schedule; an alternative that extends the 13-year schedule to accommodate extended agricultural studies; and an alternative that initiates TMDL implementation tasks based on the results of the GSWI and accelerates the 13-year schedule. Staff’s recommendation is to initiate appropriate implementation activities based on the results of the GSWI study and to accelerate the TMDL schedule if the results from the GSWI indicate that advanced treatment is required to attain the chloride WQO. Staff finds that the costs of accelerating the TMDL planning and design tasks for advanced
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esm223 20 Reading - TMDL Final Staff_Report 23Oct06 - UPPER...

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