AgdaPkt 2016-02-22 Closed and Interview and Joint SA PFA

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City of Redwood City, Public Works Division Initial Study & Mitigated Negative Declaration Document Date: October 15, 2015 Revision Date: January 25, 2016 Page 4 Blankinship & Associates, Inc. 1.0 PROJECT DESCRIPTION 1.1 Introduction and Environmental Setting Redwood City (herein referred to as the “City”) covers approximately 35 square miles with a population of about 80,000 people. The City is located on the Peninsula in the San Francisco Bay Area. The City’s Public Work Division, is responsible for maintaining the City’s Redwood Shores Lagoon (herein referred to as “Lagoon”) located within the Redwood Shores development area of the Redwood Peninsula. The Lagoon is a central point of development and contributes to the aesthetic quality, aquatic habitat, and recreation within the area. It also serves as a stormwater retention basin, providing urban flood protection by storing surface runoff during high tide periods in San Francisco Bay. The Lagoon is approximately 9,000 feet long across its main portion and is connected to sloughs leading to San Francisco Bay at six locations. Refer to Figures 1 and Figure 2. Two sloughs are gravity inlets from Belmont Slough and one from Bay Slough. There is one gravity outlet to Belmont Slough from the diamond-shaped portion of the lagoon. The lagoon’s primary source is tidal flow from San Francisco Bay through Belmont Slough and Bay Slough. In addition, there are two pump stations, referred to as Lagoon Discharge Facility 1 and 2 which pump water from the lagoon to Steinberger Slough. During the summer, these discharge facilities generally operate on a gravity outflow basis. Lagoon Discharge Facility No. 1, located in the vicinity of Waterside Drive, discharges water from the channel located between Redwood Shores Parkway and Steinberger Slough. Lagoon Discharge Facility No. 2, located adjacent to Radio Road, discharges water from the channel located just south of Radio Road. This latter facility also receives the outflow from the narrow Area 1 lagoons located to the northeast. Storm drains connect to the lagoon at a number of points along its periphery. During periods of rain, they discharge storm water into the lagoon. Most of the storm drains are connected to dewatering structures just upstream of the lagoon. The Lagoon experiences severe impacts to aesthetic and recreational benefits in addition to loss of water quality due to the presence of aquatic vegetation and algae. Nuisance algae and aquatic vegetation includes, but is not limited to, widgeon grass (Ruppia maritima) and filamentous algae (Cladophora spp.). Using Integrated Pest Management (IPM) techniques, the City or its contractor plans to apply copper-containing algaecides and/or aquatic herbicides on an “as-needed” basis to achieve aquatic weed and/or algae control necessary to maintain the lagoon’s beneficial uses. Depending on algae or aquatic weed presence, density, and species type(s), algaecides or aquatic herbicides containing copper may be applied at locations throughout the Lagoon. Applications may be made if the City’s IPM thresholds are met, or are expected to be met, based on the weather, weed density, weed growth or predicted growth, water flow, water level in the system, or resident complaints. Some years, copper-containing algaecides and/or aquatic herbicides my not be used if thresholds are not met. Applications are typically made between April and November. No algaecide or aquatic herbicide applications are made directly to the San Francisco Bay. The “Project” is defined as the City’s application of copper-containing algaecides and/or aquatic herbicides to the Redwood Shores Lagoon to control algae and/or aquatic vegetation. These applications may result in short-term or seasonal exceedances of the State Implementation Plan’s (SIP) copper Water Quality Objectives. 6.3.A. - Page 12