Sonoma County, Calif. -- Though Napa County was the first to require erosion control in new vineyards, Sonoma County has its own version. Last year, it updated the Vineyard Erosion and Sediment Control Ordinance, or VESCO, first implemented in 2000. Napa's ordinance is generally regarded as very demanding; Sonoma's version is somewhat easier to comply with in many respects.

At the recent conference, "Best Practices for Owning and Operating a Winery," conducted by the Seminar Group, Nick Frey, executive director of the Sonoma County Winegrape Commission (sonomawinegrape.org) described the process and early reaction from growers.

Though grapegrowers didn't ask for the ordinance, they had input in its creation, and seem generally satisfied with it. Frey says, "It's better to have it so people can plan and go about their business." He adds, "While it isn't everything we would want, we can work with it. It's a good compromise between environmentalists and growers."

Since 2000, the county has required a "ministerial" permit obtained through the Agricultural Commissioner. A ministerial permit is granted based upon determinations that the proposed project complies with established standards set forth in ordinances. These determinations are arrived at objectively, involve little or no personal judgment, and are issued by the planning department. These differ from another major type of permit, a discretionary permit, which requires the applicant to demonstrate compliance and approval by a decision-making body before the permit is issued.

In addition, however, some grading and drainage projects required a permit from the Sonoma County Permit & Resource Management Department. The same permits were required for agriculture and construction projects, which meant that growers often had to deal with two agencies.

Frey says that very few erosion control failures have occurred under the earlier ordinance. He added that growers have instituted widespread use of erosion controls in existing vineyards, including cover crops and straw mulch on exposed vineyard slopes, avenues and roads; straw wattles to spread and slow water flows, and they have improved vineyard management resulting in better crops.

The ordinance did call for 25- or 50-foot setbacks on blueline streams on topographic maps.

In 2008, the regulations were altered in the 2008 Grading, Drainage, Vineyard/Orchard Site Development Ordinance. It extends VESCO to cover agricultural grading and drainage reviews, and the Agriculture Commissioner is the authority that grants permits. Growers don't have to deal with the planning department--only the Ag Commissioner's office, which is more comfortable territory. Again the permits are ministerial: Meet the criteria, and you get the permit.

Environmentalists have challenged the ordinance in court, however, calling for stronger oversight, including adherence to the demanding California Enviromental Quality Assessment, an expensive and lengthy process. If the recent revision loses in court, the county will revert to the older VESCO regulations and processes.

Under the new rules, all vineyards and orchards more than one-half acre in size must meet a number of requirements. These include:

• No planting on slopes greater than 50%. (It's 30% in Napa County.)
• Setbacks are extended to unnamed streams as well as blueline streams, including 25 feet from the top of bank if it contains native vegetation, with no work allowed on this area. As an option, growers can maintain a 25-foot vegetated filter strip if there's no vegetation already there.
• For developing new vineyards, differing plans are required depending on the slope and soil conditions.
• Level 1 conditions are slopes less than 15% without highly erodible soils, or slopes less than 10% with highly erodible soils. In this case, the erosion control plan does not have to be prepared by an engineer.
• Level 2 situations are slopes more than 15% with no highly erodible soils; or slopes greater than 10% with highly erodible soils. These require an engineered erosion control plan.

Requirements for replanting vineyards are looser. Level 1 contains slopes less than 30% with no highly erodible soils or slopes less than 15% with highly erodible soils. These don't require an erosion control plan developed by an engineer, but steeper slopes do. Level 2 includes slopes more than 30% on soils that are not highly erodible; or slopes greater than 15% with highly erodible soils. These require an engineered erosion control plan.

For new vineyard and orchard development, the setbacks from streams are now 25 feet on Level 1 projects, but 50 feet on Level 2 projects.

Trickier are the setbacks from wetlands: 100 feet from county-designated wetlands, but 50 feet from undesignated wetlands, which could be any swale or depression.

The grower has an option to maintain a vegetated filter strip for 25 feet.

And now soil can't be disturbed from Oct. 15 to April 1.

Similar levels exist for agricultural grading: For "regular" grading under 5,000 cubic yards, where the cut is less than 2 feet or cut slope less than 5 feet, or a fill under 3 feet and a natural slope less than 15%, the grading plan does not have to be done by an engineer.

Engineered plans are required for grading that exceeds any of these guidelines. Likewise, drainage improvements do not require an engineered plan if the cross section area is less than 2 square feet (18-inch diameter) or the V ditch is less than 1 foot deep and its top width less than 4 feet.

Not all projects require permits. Clearing, grubbing, ripping, plowing, disking and tilling are considered routine agricultural cultivation activities if the soil disturbance is less than 3 feet deep

Road maintenance and repairs and resurfacing of existing roads are exempt, as are maintaining and repairing existing drainage improvements and minor pipe or V ditch swale systems.

The process remains ministerial, however, though some citizens are calling for stronger oversight. "Neighbors don't like change," Frey warns. "You can plant, but expect opposition." He says clearly, "New plantings are possible."

Frey suggests calling agricultural and vineyard conservation coordinator Gail Davis in the Ag Commissioner's Office to schedule a preliminary site visit before initiating design. Her number is (707) 565-2371. Frey mentioned that Cort Munselle of Munselle Civil Engineering was very helpful in preparing his comments.