Rains good for ending wildfire danger, bad for toxic runoff in burn zones
Rains good for ending wildfire danger, bad for toxic runoff in burn zones
09 November 2017
published by http://www.sfgate.com
USA: The recent rain that put a welcome end to wildfire season in badly burned Northern California has a downside: toxic runoff.
Though no major problems have been reported in the Wine Country, which was hit this week with its biggest storm since last month’s deadly fires, hundreds of workers are on the ground to prevent the remnants of scorched homes and hillsides from washing into creeks and reservoirs — and ultimately the Pacific Ocean and San Francisco Bay.
Water officials fear that heavy metals and other pollutants, as well as large doses of dirt, could muck up water supplies for both humans and wildlife. Soil erosion also could undermine roads and bridges, and mudslides could break loose on fire-ravaged slopes.
Santa Rosa and its northern outskirts are most vulnerable, officials say. A team of local, state and federal agencies is coordinating to stabilize the charred area, including the neighborhoods of Fountaingrove, Coffey Park, Larkfield and Skyfarm, so that potentially murky, contaminated water doesn’t proceed through streams and storm drains into the Russian River and to sea.
In addition to removing debris — a process that probably will run through March — crews have put hundreds of straw filters over curbside drainage inlets to catch unwanted materials, sunk nets into ditches to trap bad stuff and seeded hillsides to keep things from slipping in the first place.
Wildfires burned much of the soil and vegetation that normally sop up runoff and prevent erosion.
To the southeast, workers are targeting charred sections of Sonoma Valley and Napa Valley, where noxious runoff threatens Sonoma Creek and the Napa River, both of which run to the bay.
“So far, we haven’t seen any problems,” said Claudia Villacorta, a supervising engineer for the North Coast Regional Water Quality Control Board.
Testing for water problems is just beginning. Though the regional water board, along with a number of other natural resource agencies, has bumped up the monitoring of hundreds of creeks in Sonoma and Napa counties, most of the test samples taken since the rain remain at the lab — and they’re still collecting others.
Exactly what they’ll find remains unclear. Results will depend largely on where and how quickly runoff occurs, as well as such factors as how hot the fire burned and in what chemical state it left things.
Villacorta’s biggest concern are metals like zinc, copper and lead, washed from the rubble of homes, as well as polycyclic aromatic hydrocarbons that result from burned grasses and trees. Each is potentially toxic to humans.
Although no major reservoirs are at risk in Sonoma County, residents who get their water from wells or streams might have issues.
In Napa County, fires burned to the edge of three reservoirs, where water officials aren’t worried so much about toxic waste as they are about too much sediment. Turbidity problems haven’t surfaced, but officials are keeping a close eye on the city of Napa’s Milliken Reservoir, Yountville’s Rector Reservoir and Calistoga’s Kimball Reservoir.
Sediment also can harm the region’s fish, including threatened steelhead trout, chinook salmon and coho salmon.
“We’re mindful of what the winter can do up here,” said Mike Kirn, public works director for the city of Calistoga. “A lot of rain can come down in a short amount of time and impact the clarity of the water.”
