The project is limited to conducting one dredging episode during the environmental work window of August 1 – October 15 when temperatures throughout the water column exceed 22 degrees Celsius (i.e., when longfin smelt (Spirinchus thaleichthys) and other special-status species are not expected to occur in the project area). The
dredging episode is anticipated to be split across two years (i.e., begin during the environmental work window in 2021 and be completed in 2022) and will remove up to 3,930 cubic yards of sediment from an approximately 0.61- acre area. The project will use a cutter suction (i.e., hydraulic) dredge with a hood (i.e., an IMS Dredge, Model
6008) mounted on a 44-foot barge and operated at a maximum rate of withdrawal of 910 gallons per minute. The area will be dredged to a depth of -9 feet Mean Lower Low Water (MLLW), which includes 1-foot over-dredge. Dredging spoils will be transported through an 8-inch pipeline starting at the barge and ending at the settling basin on the Napa Sea Ranch property immediately north of Carneros Creek. The pipeline will temporarily span Creek via an approximately 4-foot wide temporary metal footbridge; both the pipeline and the footbridge will be laid by hand on the ground surface. The pipeline and footbridge will be removed immediately upon completion of the project.