Laserfiche WebLink
6 <br />1.6 WATER QUALITY CHARACTERISTICS <br />Because Redwood Shores Lagoon's primary water source is tidal flow from South San <br />Francisco Bay (Bay) through Belmont Slough and Bay Slough, the general water quality <br />characteristics of the lagoon are similar to that of the adjacent Bay. The salinity of the lagoon <br />varies considerably on a seasonal basis, ranging from 15 ppt during the rainy season to 27 <br />ppt in the late summer and early fall. Salinity in the lagoon is often slightly less saline than the <br />adjacent Bay because of its function as a stormwater retention basin and because Belmont <br />Slough drains fresh water runoff into the Bay. Water temperatures in the lagoon range from 7 <br />degrees C to 24 degrees C (45-75 degrees F) and are generally warmer than the adjacent Bay <br />waters because the lagoon is shallow and its waters have a longer residence time. Dissolved <br />oxygen levels in the lagoon usually range between 6.7 mg/L and 7.8 mg/L and pH between <br />8.0 and 8.2. The lagoon's turbidity levels range from 3.2 to 7.0 NTU with the turbidity <br />being a mix of phytoplankton and suspended sediments. <br />1.7 AQUATIC BIOTA <br />The benthic macro invertebrate and fish fauna of Redwood Shores Lagoon are typical of that <br />found in the adjacent subtidal zone of South San Francisco Bay. Based on California <br />Department of Fish and Game trawl data for the shallower waters of South San Francisco Bay, <br />the fish population of the lagoon is likely dominated by juvenile herring and anchovy, <br />topsmelt, yellowfin goby, staghon sculpin, shiner perch, bat ray, skate, leopard shark, and brown <br />smoothhound. Juvenile and adult striped bass are likely to also be present in the lagoon <br />along with an occasional white sturgeon. <br />1.8 AQUATIC WEED AND ALGAE PROBLEMS <br />Nuisance growths of widgeon grass (ruppia maritima) filamentous algae (cladophora) have <br />been problematic from the earliest years of lagoon operation. Left unchecked, nuisance growth <br />can have a severe impact on aesthetic and recreational benefits, as well as water quality in the <br />worst of conditions. Nuisance plant growth is believed to be largely a consequence of <br />lagoon design. Shallow slopes, a shallow depth, and a loss of natural tidal action all contribute <br />to promoting conditions favorable for nuisance growth. <br />6.3.A. - Page 171