Fresh and Clean
Pollutants in the Laguna de Santa Rosa get attention
By Joy Lanzendorfer
You only have to look at the Laguna de Santa Rosa to see that there’s a problem with it,” says Brenda Adelman, president of the Russian River Watershed Protection Committee. “You can see a lot of nutrient-rich growth and exotic plant growth like the water primrose, which, among other things, will produce more mosquitoes, giving rise to the concern of West Nile virus.”
The question of how much nutrients–particularly phosphorous, but also nitrogen–are polluting the laguna is the center of a new debate between scientists for the city of Santa Rosa and environmental groups.
Phosphorous and nitrogen are two elements commonly found in plant fertilizer. They are stimulating the water’s plant life, including algae. While algae in small doses are fine, too much of them can use all the oxygen in the water, suffocating fish and interrupting the ecosystem.
The laguna accounts for 10 percent of the water flowing through the Russian River. Salmon and steelhead also use the laguna as a corridor to the river. What pollutes one adds to the pollution of the other. But while most agree that the laguna is polluted, there is some dispute over which elements lead to the excess plant growth.
This month, the Environmental Protection Agency listed the Laguna de Santa Rosa for nitrogen and phosphorous impairments, meaning there are excessive amounts of both nutrients in the water. The EPA will be taking comments on the issue until July 7.
The nutrients come from several sources. Storm water carries the nutrients from lawns and landscapes into the laguna. The same rain also washes the nutrients from agriculture and dairy farms. And according to some, the nutrients also come from treated wastewater that the city of Santa Rosa dumps into the laguna from some 15 different locations.
“Santa Rosa has been dumping wastewater into the laguna for years,” says David McEnhill of the Russian River RiverKeeper Project. “Everywhere else in the U.S., phosphorous is recognized as a controller of excess algae blooms. But the city of Santa Rosa claims just the opposite. They are absolutely wrong.”
The city says that though it does test for phosphorous, it believes that nitrogen is the issue and has focused on treating nitrogen. However, if the listing remains permanent, the city may have to change how it treats phosphorous levels.
Tests done by the city show that the ratio of phosphorous to nitrogen in the laguna is about 10 to one. The low amount of nitrogen indicates that the algae use up the nitrogen and leave the phosphorous, meaning that the nitrogen is what is stimulating the plants, according to David Smith, a consultant with Merritt Smith Consulting, who acts as program manager for the city.
“First of all, there’s not a lot of evidence to suggest that the algae are what is controlling the oxygen in the laguna,” Smith says. “And secondly, we think it is the nitrogen, not the phosphorous, controlling algae.”
But scientist Dan Wickham did a study showing high levels of phosphorous in the laguna, making it what he called “probably the most impacted body of water in the U.S.” when it comes to phosphorous.
Wickham says that when the green algae use up all the nitrogen in the water, they will die out. But phosphorous-loving blue-green algae, which get their supply of nitrogen from the atmosphere, will thrive. Then, he says, the laguna will really have a problem.
“We don’t want blue-green algae,” Wickham says. “Most of it is toxic. It’s nasty stuff. It kills fish.”
The EPA has said there is an excess of both chemicals in the water. It found that nitrogen exceeded the EPA standard of 1.0 milligrams per liter of water 93 percent of the time it was tested. It also exceeded the phosphorous level 88 percent of the time. The EPA considers total phosphorus concentrations of 100 parts per billion to be impaired. In most cases, the laguna’s phosphorous concentration is at about 1,200 to 2,000 parts per billion.
The listing comes at a time of debate over Santa Rosa’s wastewater. The city of Santa Rosa is currently considering six disposal alternatives for nearly 5 million gallons a day of wastewater coming out of Santa Rosa and Rohnert Park. One of these alternatives would dump wastewater into the Russian River.
“Now that we have this EPA listing, it will limit their options,” says McEnhill. “It may come into play in other arenas as well.”
But no one knows for sure what the outcome of the listing will be. As with all listings, there will be a long process determining what will happen to whom.
“One thing we know is that the listing will have a major impact,” says Miles Ferris, department head of Santa Rosa’s Utilities Department. “And not just on the city of Santa Rosa. Whenever there’s a listing, a lot of issues come up. It’s just not that simple.”
From the June 26-July 2, 2003 issue of the North Bay Bohemian.
