Clean Water Program

Aquatic Communities Assessment monitoring stations are as follows:

Site C: Located in Mud Slough upstream from the point of discharge from the SLD. This site represents an area that received drain water before the GBP, to be reflective of drainage water removal post-project.

Site D: Located in Mud Slough downstream of the discharge point from the SLD, this site represents conditions existing immediately downstream of the discharge point.

An assessment of fish communities existing within the GBP area will be employed to evaluate changes in fish species assemblages both spatially and temporally as a result of the GBP. The assessment will describe species abundance and diversity, as well as general condition of collected organisms.

The tissue sampling is intended to provide data to compare to known critical contaminant levels to detect and predict environmental risk to the systems impacted.

Biological specimens collected will be analyzed for body burden concentrations of selenium and boron as priority analytes. If funding allows, additional analyses may be conducted for pesticides and other man-made organics, priority metals, and inorganics. All analysis for selenium residues in tissue will be by hydride generation atomic absorption spectrophotometry (HGAA). All analyses for boron residues in tissues will be by inductively coupled plasma emission spectroscopy (ICP).

Fish and invertebrates will be collected from all sites (C-I) on a quarterly basis, according to expected natural and drain water flow regimes. Sampling will occur in March (high flow), June (early summer irrigation), August (late summer irrigation), and November (low flow). This schedule will also facilitate taking biota samples to reflect temporal changes in drain water constituents. Pre-discharge baseline samples will be collected in the quarter preceding initial drain water discharges to Mud Slough.

The purposes for tissue sampling in biological specimens are: 1. to assess the potential for adverse biological impacts to fish and wildlife resources; and, 2. to assess public health risks. For the GBP monitoring plan, food chain (aquatic plants, invertebrates, and whole body fish) samples will be analyzed for contaminant residues to assess impacts to fish and wildlife resources, while gamefish fillet samples will be analyzed for contaminant residues to assess human health risks.

The sediment data will be used to detect any accumulation of selenium in the sediments. The data will also be used in conjunction with biota data from the corresponding sites to assess potential risk or contamination pathways.