County of Los Angeles Addendum to the Sun Valley Watershed Management Plan Final EIR
For the County of Los Angeles Department of Public Works, Impact Sciences prepared an addendum to the 2004 Sun Valley Watershed Management Plan Final Environmental Impact Report (Final EIR). The Approved Project consists of multiple components in the 4.4-square-mile watershed, each designed to manage stormwater runoff and reduce flooding. The majority of the components involve construction and operation of stormwater storage and/or infiltration facilities (e.g., sedimentation and infiltration basins, underground storage tanks, and dry wells). The collected stormwater would be treated prior to groundwater recharge or reuse (irrigation or gravel wash water). Where appropriate, stormwater storage facilities were proposed to provide recreational facilities and/or wildlife habitat areas. In addition, catch basins and storm drains were proposed to collect and convey runoff and reduce flows carried on street surfaces. The Proposed Project consists of four “phases” collectively known as the Sun Valley Watershed Upper Storm Drain System. The Proposed Project is part of the Storm Drains component of the Approved Project. The purpose of the Addendum to the 2004 Sun Valley Watershed Management Plan Final EIR is to evaluate the environmental effects associated with the proposed Sun Valley Watershed Upper Storm Drain System Project. Additionally, Impact Sciences conducted air quality and greenhouse gas technical analyses to support the findings of the addendum.