Albion Monitor /News

Storm Washes Urban Pollutants Into River

by Jeff Elliott

Years from now, when the New Year's Flood of 1997 is only an unhappy memory, its legacy will linger unseen as pollution in our West County soil and our groundwater, flushed there fom Santa Rosa's streets and suburban yards.

"It's not just the quantity of water you should be concerned about," says Penn State hydrologist Dr. David De Walle. "It's the quality."

Flood management is just part of the problem caused by paving over watersheds, according to De Walle. Urban runoff can be highly polluted, and critical areas, such as downstream wells and underground aquifers must be protected. Otherwise, says De Walle, "you're reducing the future water supply."

Santa Rosa City Council slashes funding for stormwater cleanup

Only this last year, however, have Sonoma County's fastest growing communities been required to address the problem. "Once the Santa Rosa area's population passed 100,000, we had to take steps," explains Colleen Ferguson, an associate civil engineer with the City of Santa Rosa. "The Clean Water Act required us to get a permit for stormwater runoff, just like we had to have one for wastewater."

Santa Rosa now has a program that will cost $495,000 annually. The emphasis, says Ferguson, is on "source control instead of treatment -- stopping it before it gets to the creeks."

The county and city will be educating the public about lawn herbicides and fertilizers, home automotive work, and other pollutants that wash into the creeks from backyards and driveways. This is the largest source of the problem, Ferguson says; local industry plays only a small role. The program will also pay for city crews to routinely clean storm drains.

Drain cleaning and public ed was only half of the program envisioned; also planned was creek restoration, including revegetation along the banks, which acts as a natural filter for runoff pollutants. But Santa Rosa City Council slashed program funding last month, declaring that urban property owners were being unfairly soaked for money.

Originally, the Santa Rosa City Council passed a $19 per residential unit assement last fall. In December, however, the Council cut that figure almost in half. Noting that there was already a $10/parcel assesment for flood control that goes to the County Water Agency, the Council decided to knock an equivalent ten bucks off the stormwater bill.

74,000 pounds of nitrates annually from Santa Rosa lawns and gardens

Although the quantities of chemicals and metals flowing from the Santa Rosa plain are thought to be enormous, no long-term data exists. The runoff varies from year to year because of the frequency and intensity of winter storms. And only recently has Santa Rosa begun sampling stormwater quality.

Also, Ferguson says, "it's a new field, and it's hard to figure out where some of [the pollution] is coming from." As examples, she explains that higher levels of copper found in South San Francisco Bay runoff is thought to be coming from some brands of brake pads. The chromium that's appearing in the storm water is likely from little bits of metal flaking off our cars and trucks.

Whatever the source, the levels are staggering. The amount of nitrates draining into the water from the urban Santa Rosa area is estimated to be about 74,000 pounds per year -- most presumably coming from lawn and garden fertilizing. About two tons of chromium is thought to come from shiny automobiles in the Windsor to Rohnert Park sprawl.

It was results of nationwide studies during the 1980s that led Congress to pass these amendments to the Clean Water Act, but research is only beginning. In November, the U.S. Geological Survey (USGS) released a report that said a gasoline additive was found in 3 out of 4 samples of stormwater from cities where it is used in gasoline.

This additive, MTBE, is added to gasoline in many parts of the United States to increase the octane level or to reduce carbon monoxide and ozone levels in the air. The U.S. Environmental Protection Agency tentatively classifies MTBE as a possible human carcinogen. All levels of MTBE detected in groundwater were below the EPA draft lifetime health advisory limits for drinking water.

It also acts as a marker showing how gasoline products have entered the water supply. MTBE was detected in 23 percent of New England's deep domestic-supply wells that tap fractured bedrock aquifers. These contaminated wells were only in suburbanized Connecticut and Massachusetts, and none of the sampled bedrock wells were within a quarter-mile of a gasoline station.

The USGS measured concentrations of 62 volatile organic compounds (VOC's) and other constituents in 592 stormwater samples, collected from 16 cities with a population greater than 100,000. MTBE was the seventh most frequently detected VOC, found in 41 of the samples.

In decreasing order, the most frequently detected VOC's were toluene, total xylene, chloroform, trimethylbenzene, tetrachloroethene and naphthalene. VOC's are of concern because they are easily changed into gaseous form (volatilized) and, therefore, available to the air and water.

Further information on the groundwater study is available from the USGS National Water Quality Assessment Program home page.

Flooding Linked to Development, Researcher Says

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Albion Monitor January 7, 1997 (

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