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NORTH COAST – Regional regulations for control of rainwater-borne sediment and other listed pollutants from construction sites in the erosion-prone North Coast could be coming into closer alignment with state rules as both release new drafts of their governing policies.

On April 23, the State Water Resources Control Board issued a third draft of an update to the statewide general permit for discharges of stormwater associated with construction activities.

Meanwhile, the North Coast Regional Water Quality Control Board plans to release this month a second draft of an update to the stormwater permit for Sonoma County, Santa Rosa and the Sonoma County Water Agency to address a number of concerns about the first draft in October, according to senior engineer John Short. The regional permit covers runoff from construction as well as other potential sources of water contamination, such as landscaping.

One of the more controversial items in the North Coast’s draft was what is known as low-impact development, which entails project design that keeps the speed or amount of water moving off a property similar to before construction. The new state draft has such a provision, called post-construction stormwater performance standards.

“We’re playing catch-up ourselves with the calculators and how token construction projects will fall under that system,” Mr. Short said. He noted that features of both drafts are similar, with the statewide draft expanding the rules to areas not covered by municipal stormwater permits.

In addition to a proposed calculator for figuring post-construction performance, there’s a calculator in the state board’s new draft for a risk-based permitting system with three levels – low, medium and high – affecting the degree of project scrutiny. Those levels are determined on the risk of sediment movement based on characteristics of the site and nearby waterways.

Regulators have declared a number of North Coast waterways as having “impaired” water quality, partly because the region is erosion-prone, according to Mr. Short. That impairment triggers regulations for protected species.

“The amount of rain we get and the slope characteristics mean that we tend to have a higher percentage of projects in higher-risk areas,” he said.

Yet builders, winegrape growers, ranchers and rural property owners can reduce that risk level by agreeing to keep soil-moving activities to the dry summer months and outside setbacks from waterways, according to Mr. Short. Both are common features of grading ordinances adopted throughout the North Coast in the past several years.

Beside the risk levels, the new state draft permit contains controversial numerical benchmarks and rules for electronic submittal of all documents for immediate Internet posting. Exceeding the thresholds could bring enforcement if not corrected. The proposal has “numeric action levels” for acidity and turbidity. The other proposed metrics are daily average “numeric effluent levels” for tubidity from risk level 3 projects and for pH during high-risk job phases, such as pouring concrete.

Construction groups have objected to those metrics since a blue-ribbon panel of experts first developed them in 2006, calling the thresholds unfair to project proponents, according to environmental law attorney David Ivester of Briscoe Ivester & Bazel.

“Builders and others have expressed concerns about the legality and practicality of some of these proposed changes, particularly the NALs and NELs,” he said. “Stormwater discharges, they have observed, are unlike other discharges of pollutants in that industry generally controls the materials and processes involved, but builders do not control the weather.”

However, Bill Wilson, a Mill Valley-based designer of stormwater control and mitigation measures for projects locally and globally, called those metrics a “major aid” in consistency of preparation and oversight of site management, stormwater mitigation, and grading and drainage plans.

“I especially appreciate the emphasis on the need for maintenance and the resulting implied push towards selecting approaches that are going to be more easily serviced,” Mr. Wilson said.

The deadline for comments on the latest draft of the statewide permit is June 17, and a hearing is set for June 3 in Sacramento. The latest draft is posted at www.swrcb.ca.gov/water_issues/programs/stormwater/constpermits.shtml.