Invasive Plants are Taking Over Mount Tam

On a Friday in late June, the Marin Municipal Water District held an emotional hearing on use of the herbicide glyphosate. One speaker argued the chemical, most commonly known as Roundup, is a cost-effective way of controlling invasive plants now threatening the biodiversity—and maximizing fire danger—on Mount Tamalpais. Others claimed glyphosate is a carcinogen and urged that the district not hire consultants to study the issue until the Environmental Protection Agency reevaluates its own opinion of the herbicide.

These days, convincing anyone to use a chemical in order to benefit the environment is a challenge. But, the more I study the subject, the more I’m convinced it’s necessary.

First, chemicals are too widely cast as the boogeyman of environmentally conscious living. Let’s accept the reality that chemicals are integral parts of our daily lives. There’s chlorine in our drinking water, for example, and salt in our food. Concurrently, we do not want any more chemicals than what’s necessary. That said, in order to preserve Mount Tam’s biodiversity and protect nearby homes from wildfires that use overgrown hillsides for fuel, I maintain that a judicious amount of the herbicide glyphosate should be used.

Sharing this position is Jake Sigg, former president of the California Native Plant Society. “People in Marin don’t realize the huge problem existing on Mount Tamalpais,” he says, referring to the infestation of Scotch and French broom, an invasive, nonnative plant that already dominates hundreds of acres on Mount Tam. “With time, this watershed will become a monoculture environment because broom, and other nonnatives, not only choke out native plants but also starve out native animal life.” Sigg, an avid hiker who’s studied the issue for years, explains it this way: “Thousands of insects live on native plants; birds and critters feed on those insects; and so forth on up the food chain.” In his view, “glyphosate is by far the most cost-effective way” of controlling nonnative plants.

The Marin Municipal Water District, which manages 22,000 acres of open space including the Mount Tam watershed, appears to agree with Sigg. A recent district study indicates spot herbicide application (not spraying), kept distant from reservoirs and streams, costs $2,825 per acre while hand pulling, planned burns, propane flaming and goat grazing range from $5,300 to nearly $10,000 per acre—and aren’t as effective nor as safe.

In fact, the district used herbicides until August 2005, when opposition from the Marin Safe Drinking Water Coalition (led by Belvedere doctor William Rothman and former Fairfax mayor Frank Egger) convinced the agency’s board of directors to halt the practice. The current board is about to hire a consultant to re-evaluate solutions, including herbicides, and now Rothman, Eggers, and others are advocating not even studying the issue.

Rothman says he does not think the water district should do a study because the EPA, which years ago approved glyphosate as an herbicide, anticipates reopening its analysis of the chemical’s effect on humans. That process, says Rothman, “won’t be completed until 2012, so why have MMWD spend tens of thousands of dollars studying it now?” To me the answer is obvious: Mount Tam’s native plants and critical firebreaks are currently being overrun with nonnative plants—and the longer we delay action, the harder and costlier it will be.

Is glyphosate safe? As far as this layman is concerned, the answer is yes. Properly applied, it destroys the individual plant only, with little (and benign) impact on surrounding soils. The National Audubon Society, whose mission is “to conserve and restore natural ecosystems … for the benefit of humanity and the earth’s biological diversity,” refers to glyphosate as a “strikingly benign herbicide.” Furthermore, after reading extensively on the subject, I found no credible evidence that glyphosate is carcinogenic.

Glyphosate is used to control invasive plants by California’s Department of Parks, Caltrans, the city of San Francisco, Golden Gate National Recreation Area, Point Reyes National Seashore, Audubon Canyon Ranch, Marin County Open Space District and most Marin cities.

Herbicides containing glyphosate, as in Roundup, are available at any local garden store for public use. Why shouldn’t the MMWD have the same right to use it? I strongly endorse the balanced useage of this herbicide.

That’s my point of view. What’s yours?

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