Larkspur Marina Bulkhead Replacement Project (Notification of Lake or Streambed Alteration, No. EPIMS-MAN-56958-R3 Amendment No.1).

The California Department of Fish and Wildlife has amended Lake and Streambed Alteration Agreement EPIMS Notification No. EPIMS-MAN-56958-R3 (Agreement), pursuant to Section 1602 of the Fish and Game Code, to Larkspur Marina Property Owners’ Association. The amendment allows an increase of temporary impacts associated with additional floating platforms and a temporary access dock, and changes to four Agreement measures. The Project is limited to replacing the existing bulkhead wall by constructing a new bulkhead wall built on the waterside of the existing bulkhead along the Lake shoreline. The new bulkhead will be constructed with fiber reinforced vinyl sheets and placed via vibratory method with a small excavator, no pile driving will take place. Access for equipment and materials will take place from a temporary dock approximately 2.5 feet long by 15 feet wide, which will be secured with eight seven-inch diameter shaft helical piles, which will be installed and removed by screwing into and out of the Lake bed using a screw-in attachment to an excavator. Construction of the new bulkhead will be conducted from three floating platforms, two approximately 40 feet wide by 60 feet long and one approximately 60 feet wide by 30 feet long. The concrete cap of the existing bulkhead will be removed as necessary. The space between the existing bulkhead and the new bulkhead will be filled with compacted fill material and a new cap will be installed. Turbidity controls (e.g., silt curtains or similar) will be used around the active work areas, which will allow suspended solids to drop out and minimize turbidity in the Lake. The Lake inlets will be closed off by November 30 which is the end of the work period for larval Longfin smelt (Spirinchus thaleichthys) for the duration of construction activities. The Lake outlet, which is controlled by a one-way duckbill valve, will remain operational and used to lower lake levels as necessary to maintain flood control operations and water quality. A pump system connecting to Corte Madera Creek side channel and the Lake will be used to raise the level of the Lake as necessary during wet and dry seasons to maintain water quality, flood control, and integrity of the existing bulkhead. An existing easement over the outfall pipe in the northeast section of the Lake will be used for access to the floating platforms and staging materials and equipment. The Project will result in 162,141 square feet (3.72 acres) of temporary impacts associated with shade and piles caused by the temporary dock for project access, three floating platforms traversing through the Lake, and the use of silt curtains, which shall all be removed immediately after Project completion. The Project will result in 8,538 square feet (0.196 acres) of permanent impacts associated with bulkhead construction and fill.