MARINE BIOLOGICAL RESOURCES. CEQA FINDING NO. MBIO-1 Impact: MBIO-1. Sediment resuspension during dock/piling removal and installation, and dredging activities. Finding(s): (1) Changes or alterations have been required in, or incorporated into, the project that mitigate or avoid the significant environmental effect as identified in the EIR. FACTS SUPPORTING THE FINDING(S) Dredging activities could result in an increase in water column turbidity and an associated decrease in dissolved oxygen concentration from re-suspended sediments. Disturbed water column conditions may contribute to: 1) a decrease in light penetration and cause a general decline in aquatic primary productivity; 2) clogging the respiratory and feeding apparatuses of fish and filter-feeding invertebrates; 3) altering fish distribution and behavior; and/or 4) the deposition of sediment and burial of infauna or immobile epibiota. Fish may depart and/or avoid the turbid water areas, reducing foraging opportunities for special status bird species including pelicans and terns. Although some fish may avoid the immediate area due to an increase in suspended sediments, other fish and avian species could be attracted to the area to feed on floating organisms that are removed during these operations. Dredging activities would most likely contribute only a relatively minor increase to the naturally turbid conditions of the Bay. Mitigation will reduce the regional impacts by confining the turbidity to the immediate vicinity of dredging activities. Eelgrass, a plant species of concern is present within areas that are proposed to be dredged and in adjacent sedimentary habitats outside of the Marina. The settling of resuspended sediment onto those plants could result in a potentially significant impact to the overall population with the Bay. The following mitigation measures will be implemented to reduce the impacts to less than significant. Mitigation Measure MB‐1. Silt screens should be used around all in‐water, bottom disturbing activities when and where they will be effective.
MARINE BIOLOGICAL RESOURCES. CEQA FINDING NO. MR-C (CUMMULATIVE) Impact: Impact MR-C. Cumulative Impacts to Marine Marine Biological Resources. The Project may make a considerable contribution to marine water quality significant cumulative impacts, which may adversely affect marine biological resources. Finding(s): (1) Changes or alterations have been required in, or incorporated into, the project that mitigate or avoid the significant environmental effect as identified in the EIR. FACTS SUPPORTING THE FINDING(S) The desalination discharges would result in a significant impact to marine water quality, which in turn, could adversely affect marine biological resources. The proposed mitigation would involve employing one or more design features and/or operational measures prior to operating the desalination plant. The design features and operational measures include short-term storage and release of brine from the desalination plant, treatment of the source water and/or brine discharge(s), and biologically active filtration at the Regional Treatment Plant. With implementation of MM HS-C, the impact would be reduced to less than significant and the Project would not make a considerable contribution to a significant cumulative impact MM HS-C: Implement Measures to Avoid Exceedances over Water Quality Objectives at the Edge of the Zone of Initial Dilution. LEVEL OF SIGNIFICANCE AFTER MITIGATION. With the mitigation described above, this impact is reduced to a less than significant level.
