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7 <br />2.0 AQUATIC PESTICIDE APPLICATION PLAN <br /> <br />To control the excessive growths of widgeon grass and filamentous algae in Redwood <br />Shores Lagoon during April through September, the City contracts with a consultant <br />certified for aquatic pesticide application to manage the aquatic weed and algae in the <br />lagoon. The consultant is responsible for weekly surveys of the lagoon to determine the <br />extent of aquatic weed and algae growth, plus aquatic weed harvesting and the applications of <br />aquatic pesticides. Mechanical harvesting is used to remove most of the widgeon grass when <br />it's sufficiently high. When widgeon grass occurs in shoreline waters too shallow for the <br />mechanical harvester, these areas are spot-treated with Reward, an herbicide with diquat as <br />its active ingredient. While filamentous algae is regularly raked out of the area around the <br />public boat launch ramp, most of the algae around the shallows are treated with Earth Tee <br />or a chelated copper algaecide if the Earth Tee isn't available. <br /> <br />Described below is the plan for managing Redwood Shores Lagoon to minimize the need for <br />aquatic pesticide applications, and the application plan to be followed when aquatic <br />pesticides are needed to maintain the lake's beneficial uses. <br /> <br />2.1 APPLICATION PERIOD <br /> <br />The aquatic plant (widgeon grass) and filamentous algae nuisance season typically <br />extends from late April into September. The widgeon grass problem generally occurs in <br />May and June. Nuisance algae growth extends from late April into September. While <br />mechanical harvesting is presently employed for the removal of widgeon grass where <br />feasible, widgeon grass in the shoreline waters too shallow for the mechanical harvester are <br />spot-treated with Reward, an herbicide with diquat as its active ingredient. Some algae are <br />removed as a byproduct of mechanical harvesting the widgeon grass. However, much of the <br />algae must be spot treated with Earth Tee, a copper-based algaecide. <br /> <br />2.2 TOOLS AND TECHNIQUES <br />The strategy for controlling aquatic weeds and algae in the lagoon is to favor the growth of <br />widgeon grass over filamentous and planktonic algae. By regularly removing the widgeon <br />grass through mechanical harvesting, the lagoon's nutrients assimilated by these aquatic <br />macrophysics are also removed from the lagoon. For this reason, blooms of planktonic <br />algae (microscopic, free floating algae) are treated with Earth Tee whenever the lagoon's <br />water clarity becomes less than 2 feet as a result of planktonic algae. The mechanical <br />harvesting and application of aquatic pesticides are conducted by the consultant. <br />Mechanical harvesting is utilized extensively in areas negotiable by harvesting <br />equipment. Generally, a minimum water depth and clearance from stationary encroachments <br />(e.g., docks and boardwalks) are required for safe equipment operation. <br />Pesticides are applied to areas deemed not feasible for harvesting. The aquatic pesticides <br />shown below in Table 1 are applied to Redwood Shores Lagoon in the manner described. <br />6.3.A. - Page 172