Finnon Reservoir Water Supplementation Project

The El Dorado Irrigation District (EID) is providing a permanent supplemental water supply for Finnon Reservoir to ensure the reservoir has sufficient water in storage during the summer recreational and fire season. The reservoir water supply historically included watershed runoff and supplemental releases from an EID canal. EID terminated its canal discharges to the lake and is proposing to provide potable water releases as the replacement water supply. In part due to the proposed potable water releases containing residual chlorine and other potential contaminants, the project is subject to review and permitting by the Central Valley Regional Water Quality Control Board. RBI assisted with special studies and permitting to develop a cost-effective engineering and regulatory compliance solution for the project, including the following:

• Prepared a sampling and analysis plan (SAP) to provide data to aid the design of natural or engineered passive dechlorination system options.  Designed field experiments, analyzed experimental data, derived chlorine decay constants, and performed preliminary sizing/design calculations.
• Prepared secondary sampling and analysis recommendations for the evaluation of trihalomethane compound removal performance via passive removal methods.
• Reviewed project constraints with respect to water quality laws and Basin Plan policies; provided recommendations for regulatory compliance analyses and documentation.
• Prepared application package for authorization under the Central Valley Water Board’s Limited Threat Discharges of Treated/Untreated Groundwater from Cleanup Sites, Wastewater from Superchlorination Projects, and Other Limited Threat Wastewaters to Surface Water (Order No. R5-08-0082, NPDES Permit CAG99502).
• Assisted with discussions and negotiations with the Central Valley Water Board to obtain the permit.