This annual report summarizes the results of the 2004 water quality sampling conducted at the Alviso Salt Ponds in Santa Clara County, which are part of the South San Francisco Bay Low Salinity Salt Ponds. Operations occurred from July through December 2004. Sampling was performed on a continuous, weekly, monthly or bi-monthly schedule as required by the Final Order (No. R2-2004-0018). Sampling was performed by U.S. Geological Survey (USGS) on behalf of the U.S. Fish and Wildlife Service (FWS) in accordance with the waste discharge

The Final Order for the South San Francisco Bay Low Salinity Salt Ponds covered 15,100 acres of ponds in Alameda, Santa Clara and San Mateo Counties. This report only covers Alviso Pond Systems A2W, A3W and A7 operated by the Don Edwards San Francisco Bay National Wildlife Refuge in Santa Clara County. Other ponds in Santa Clara County and the ponds in San Mateo County were not opened to the Bay in 2004 and hence are not covered in the 2004 Annual Report. The California Department of Fish and Game will be submitting a report for the Eden Landing (Baumberg) Ponds under a separate cover.

The ponds are generally being operated as flow-through systems with Bay waters entering an intake pond at high tides through a tide gate, passing through one or more ponds, and exiting the discharge pond to a tidal slough or the bay at low tides. The ponds only discharge at low tides, generally about 6 or 8 hours per day. Two ponds in the Alviso system (Ponds A3N and A8) were operated as seasonal ponds during 2004 and were not connected to the flow-through system.

The Final Order recognized two periods of discharges from the ponds: the Initial Release Period when salinity levels would decrease from the initial levels in the ponds and a Continuous Circulation period after salinities reached the 44 ppt salinity discharge limit. Different monitoring plans were identified in the Final Order for each specific period.