Laserfiche WebLink
<br /> <br />The lagoon is connected to sloughs leading to San Francisco Bay at six locations (see Figure <br />2). There are two gravity inlets from Belmont Slough and one from Bay Slough. There is one <br />gravity outlet to Belmont Slough from the diamond-shaped portion of the lagoon. The lagoon's <br />primary water source is tidal flow from San Francisco Bay through Belmont Slough and Bay <br />Slough. In addition, there are two pump stations, referred to as Lagoon Discharge Facility 1 <br />and 2 which pump water from the lagoon to Steinberger Slough. During the summer, these <br />discharge facilities generally operate on a gravity- outflow basis. Lagoon Discharge Facility <br />No. 1, located in the vicinity of Waterside Drive, discharges water from the channel located <br />between Redwood Shores Parkway and Steinberger Slough. Lagoon Discharge Facility No. 2, <br />located adjacent to Radio Road, discharges water from the channel located just south of Radio <br />Road. This latter facility also receives the outflow from the narrow Area 1 lagoons located to the <br />northeast. <br />The lagoon bottom is at elevation 93.0 feet (National Geodetic Vertical Datum (NGVD) <br />+100'). The lagoon water level is kept at elevations 97.0 feet and 99.0 feet during the winter <br />and summer, respectively. Near the water's edge, the surrounding land's grade elevation is <br />approximately 102 feet. The Redwood Peninsula is surrounded by exterior levees that vary in <br />elevation between approximately 107.5 feet and 109.0 feet. Storm drains connect to the <br />lagoon at a number of points along its periphery. During periods of rain they discharge storm <br />water into the lagoon. Most of the storm drains are connected to dewatering structures just <br />upstream of the lagoon. <br />The local watershed contains some office buildings, but otherwise is a residential area. The <br />perimeter of the lagoon is developed with single-family homes and private docks along the <br />majority of shoreline, interspersed with several small public parks. <br /> <br /> <br />1.4 LAGOON OPERATIONS <br /> <br />Routine municipal maintenance tasks include maintenance of operating levels, water exchange <br />and flushing rates, pump stations and other infrastructure, aquatic plant nuisance control, <br />water quality protection, water recreation, regulation of encroachments and bank alteration, and <br />other activities. The flushing rate is the rate at which lagoon water is replaced with water <br />from an external source, in this case from Belmont Slough and Bay Slough. Flushing rate <br />may be defined as the number of times that the entire lagoon volume is exchanged over a <br />given period of time. An average flushing rate of once every 7 days is considered to be the <br />optimum exchange rate, but this is rarely achieved. <br /> <br />Lagoon water exchange is accomplished via the previously described inlets and outlets <br />connected to the surrounding sloughs. Inflow to the lagoon takes place through the three gravity <br />inlets when tide levels are higher than the level in the lagoon. Findings from previous <br />studies, current operational experience and a review of local tide levels indicate that gravity <br />inflow to the lagoon is more than adequate to restore lagoon levels following a low tide period. <br />Outflow from the lagoon is through a gravity outlet to Belmont Slough and through two pump <br />stations which discharge to Steinberger Slough. Gravity discharge <br /> <br /> <br />3 <br />6.3.A. - Page 168