Green infrastructure could cut stormwater pollution in Ventura County

Mercer 10058

Molly Peterson/KPCC

Stormwater, handled separately from waste water out of treatment plants, runs down paved streets and into storm systems - or just over the edge of a cliff. With it, water takes hydrocarbons, pollutants, pesticides, bacteria into the ocean.

A welcome rainstorm cleans the skies and the streets but sends a chemical soup flowing into the ocean. State regulators are putting in new rules to capture much of that runoff before it fouls the coastal waters.
 
In Ventura County, those rules calls for changes in the way gutters and culverts direct rainfall runoff. The approach has developers and cities worried.

Before concrete, only 10 percent of rainwater made it to the ocean. The rest evaporated or sank into the ground.

But paved surfaces from Ojai and Simi Valley to Point Hueneme and Point Mugu give rain a perfect path to the sea, "picking up with it animal waste and bacteria and pathogens and whatever happens to be lying in the street," says Noah Garrison, a lawyer with the Natural Resources Defense Council. "It delivers that straight into waters, usually without any treatment at all."

Garrison says the runoff violates federal clean water standards at every monitoring station in Ventura County and all along California’s coast. "The problems with stormwater are not going away," he says. "They are not getting better, and it’s clear that the methods we’ve been using to treat stormwater and release it into our rivers and our ocean and polluting our beaches are simply not working."



Those methods have focused on filtering and treating water at the end of the pipe. Ventura County's new rules now promote low-impact development – ways to mimic natural pre-pavement conditions. Such rules change the shape of the pipe – or get rid of it entirely.

Deb Smith works on these issues for the L.A. Regional Water Quality Control Board. "What we’re trying to do with low-impact development is maintain the flows on site, maintain the pollutants on site, such that when we construct a new project we’re not changing the previous condition that we had in the area," she says.

In other words: if it didn’t run off before people got here, it shouldn’t run off now. Capturing rain where it falls in Ventura is complicated by sudden and intense seasonal storms.

The new rules encourage cupping rain in swales to let it evaporate or sink below the surface, stored between sand and rock. City officials say that could be difficult.
 
Up through so-called French drains comes a trickle of water at some places in Thousand Oaks. Public works director Mark Watkins says groundwater seeps down slopes even in summer’s dry heat. "We’re primarily built on solid rock and so the water can’t infiltrate," Watkins says.
 
In places like that, Ventura County’s new rules let projects treat and release more runoff someplace else. Watkins says the options are good, but he also believes what Thousand Oaks already does works. "We’ve been doing stormwater quality for a long time," Watkins says. "As far as we know, this is the most onerous stormwater permit that’s ever been issued."
  
A car door slam echoes deep in the Oaks Mall parking garage, where Watkins shows me a basin the size of a swimming pool. It was built to protect against huge storm flows.

Watkins says the new rules want almost the opposite; basins like this would capture almost all water from more frequent smaller storms. "It’s a good 15 feet deep by 30 years long by 50 yards," Watkins says, pointing. "Under the new permit this would have to be four times bigger than it is now and have a soft bottom presumably to allow water to infiltrate."
 
"Administratively, this is going to be a nightmare," says Jeff Pratt with Ventura County Public Works. They’ll explain and enforce the new runoff rules.

Pratt says the county has to balance the rules with smart growth requirements, “greenhouse gas” rules – and with housing and budget mandates. "We’ve got affordable housing numbers we have to hit and we can’t hit that with additional expenses, because essentially what this requires is more land – more land than normally would be required for development in the old way of letting water run off."
 
Consultants and cities are suggesting lots of exceptions. The NRDC’s Noah Garrison says too many exceptions won’t keep coastal waters clean. "When 100 percent of the water doesn’t leave the site, 100 percent of the pollution doesn’t enter our waterways," he points out.
 
Mary Lynn Coffee, a lawyer with the firm Nossaman, says the economy’s already frozen many projects she represents. Coffee says low-impact development could prevent a faster thaw. "Probably one of the more difficult things for developers now who are trying to reinitiate projects is that the rules are all new and the rules require redesign, which is cost-intensive," she says.
 
Coffee believes it could take two years to see how low-impact development rules for stormwater affect building costs. But the water board’s Deb Smith says those aren’t the only costs that matter. "I think we also have to keep in mind that there is a cost if we don’t protect water quality to the health of folks swimming in our coastal waters and to the ecosystem as well," says Smith.
 
All the costs of low-impact development will be a little clearer once Ventura’s stormwater plan becomes final this fall. After that, water regulators will turn to a bigger job: setting the runoff rules for Los Angeles County. 

More in Environment / Science

Comments

blog comments powered by Disqus