NITROGEN IMPERILING RIVER HIGH LEVELS POSE THREAT TO ECOSYSTEM.

Byline: Nicholas Grudin Staff Writer

SANTA CLARITA - High levels of nitrogen in the Santa Clara River could be seriously damaging the watershed's ecosystem, according to a study by UCLA scientists.

Portions of the Santa Clara River downstream from the Saugus and Valencia sanitation plants have 20 times more nitrogen than other Southern California waterways sampled in the study, and the population of important bottom-dwelling aquatic insect larvae was significantly depleted.

``We found that while most indications are that there should have been a healthy (larvae) community, we found that there was not,'' said Steven Lee, who prepared the report with professor Richard Ambrose and Sean Bergquist. ``One of the possible causes or influences is that we found really high nitrogen levels.''

The Santa Clara River flows from Acton to Oxnard, where it empties into the Pacific. Dry most of the year, the river is home to a variety of rare aquatic species, birds and small mammals. Efforts have been under way to protect those habitats as development continues on its banks.

``The reaches where they saw the problem contained endangered species in 1995,'' said Elizabeth Erickson, an associate engineering geologist for the Los Angeles Regional Water Quality Control Board, which sponsored the study.

``With Newhall Ranch just approved in that vicinity and the waste treatment plant that discharges into that reach scheduled to increase its output from 12 cubic feet per second to 22 cubic feet per second within the next 12 years, my question is, can the fish survive with that future?'' Erickson said.

Populations of certain insect larvae that develop within riverbeds - such as the infant forms of mayflies, stoneflies and caddisflies - are considered by scientists to be ``indicators of the general health of the ecosystem,'' Lee said.

Low larvae populations mean that a river's entire wildlife population could be at risk.

In the case of the Santa Clara River, the pertinent larvae populations dropped by as much as 50 percent downstream from the Valencia and Saugus sanitation plants.

``We found significant reductions in the numbers of indicators of healthy conditions,'' Lee said.

Officials from the water board said they would need more time to analyze the study by the University of California, Los Angeles, to draw any conclusions on what needs to be done.

The Saugus and Valencia water plants are already in the process of altering their sanitation methods to use less ammonia and therefore decrease the water's nitrogen content, but environmentalists say more needs to be done.

``The UCLA report clearly demonstrates that the river is already an impaired waterway,'' said Teresa Savaikie, an activist in Santa Clarita. ``Here we have the only living river in L.A. County - that should be the other way around. Once these things are gone, they're gone.''

Erickson said that more studies would be in order.

``There is something happening there that should be assessed further,'' Erickson said.

Nicholas Grudin, [phone]

nicholas.grudin(at)dailynews.com