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South Bay Refresher

Despite a massive new local water recycling system, saltwater marsh in the South Bay continues to be converted to brackish marsh, though whether due to El Niñoo or wastewater discharges is still under debate.

About 8% of the marsh near the San Jose/Santa Clara Water Pollution Control Plant's outfall disappeared during the El Nino winter of 1997-1998, the same loss that occurred in other spots like Guadalupe Slough. According to both the Regional Board's Wil Bruhns and Lindsay Wolfe of San Jose's Environmental Services Division, the plant's discharges remain below the Board- ordered limit of 120 million gallons per day. Bruhns also points out that the scale of marsh conversion has diminished.

U.S. Fish & Wildlife's Peter Baye says heavy discharges into Artesian Slough and Coyote Creek continue to be a problem. "The marsh conversion is very real and it's been progressive. In drought years, you see a very exaggerated impact; in wetter years, it's harder to read. It's hard to say with precision how fast the conversion is occurring because people interpret the vegetation differently (whether salt marsh or freshwater), but the conversion probably tracks the volume of discharge."

Baye says the conversion is not just associated with the volume of the discharges but the season in which they occur. "During the growing season, the vegetation responds more to discharges." Baye says that one of the problems in the South Bay is that before massive levee construction and Bay filling, freshwater discharges were distributed over a wide area of the South Bay; today they are concentrated in narrow, levee-lined streams.

One solution would be to do something totally different than recycling, like using excess freshwater to replenish groundwater, suggests Baye. Another would be recreate a complex network of channels and marsh. "The long term solution is to restore a lot of tidal marsh," says Baye. "In the short term, instead of discharging into narrow concentrated sloughs with no potential for dissipation, we could send the discharges into some of the salt ponds as they become available for acquisition, and use them as tidal mixing basins so they can offer some multiple use benefits." To avoid impacting birds that now use the salt ponds, says Baye, the water in the mixing ponds could be re-mixed with Bay water to increase the ponds' salinity.

"These discharges need not be a problem. They could be used to replicate natural systems if we could just manage them differently or restructure the habitat to accept them differently. Because as we all know, growth in the South Bay is not going to go away."

Contact: Peter Baye (707) 562-3003; Wil Bruhns (510) 622-2327; Lindsay Wolf (408) 277-5533

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