Environmental interest groups are convinced the devil is in the details when it comes to the county’s new draft general plan update — a kind of land-use planning blueprint — and they want time to look them over.

Friends of the Napa River and other local environmental groups are gearing up to pressure the county to extend a public comment period on the county’s draft general plan that will be released to the public Friday.

The county is scheduling a 60-day comment period, but Bernhard Krevet, president of Friends of the Napa River, said his and other local groups want at least 120 days to look over the planning document.

“Obviously it’s going to cost more money to drag out, but this is something that is going to guide the future for Napa County for the next 20 years or so,” he said.

That’s also the plan with other groups like the Napa County Farm Bureau.

“We agreed that there is a need for more than 60 days of review,” said Sandy Elles, executive director.

As it stands now, the county scheduled three public comment hearings, March 21, March 28 and April 4 — all explained on its Web site, www.napacountygeneralplan.com.

If local groups are successful, the county might schedule more hearings.

At a Napa County Board of Supervisors meeting last week, Napa County Planning Director Hillary Gitelman outlined the four major changes to the general plan: The addition of “transitional” zoning areas at the old Napa Pipe property near Kaiser Road, a choice of three maps of Angwin outlining areas that can be developed without a countywide vote, policies that would fast track vineyard projects deemed environmentally superior and a rural urban limit line for American Canyon that is slightly smaller than what the city desires.

The Angwin question drew more than 120 people to a recent meeting of the General Plan Steering Committee, and with the likelihood that one of three maps sent to the public for comment would send Pacific Union College officials “back to the drawing board” to recompose their plan to build nearly 600 homes in Angwin, controversy is likely to dog the general plan’s every step.

“Angwin may be the knottiest problem we have,” said Peter McCrea, General Plan Steering Committee chairman. “For the time being we’re hoping the community comes to a consensus on what to do.”

Besides slow-growth Angwinites, controversy may come from south county as well. The city of American Canyon hopes to use the public comment process to enlarge the rural urban limit line that the county plan would draw around its city.

“We’re the only city that does not have a committee member on the General Plan Steering Committee,” said American Canyon City Manager Richard Ramirez. “So it came as a surprise that they did not follow the city’s general plan. ... It’s the general plan that the city has adopted since 1994. We’re looking forward to working with the county to iron out these inconsistencies and we’re looking forward to a mutually agreeable solution.”

Krevet said his group also wants to see environmentally-friendly policies set out in areas like recreation, transportation and housing, as well as a new river element to the plan to formalize so-called living river principles set out by Measure A, the flood tax initiative that provides local funding for flood projects up and down the valley.

All that will take time to see how it will fit into the draft plan that will be released Friday.

“The public needs time to review,” Krevet said. “I can’t tell anyone ‘I need this by Tuesday,’ we have to work around other schedules.”

McCrea, for his part, said  he hopes the schedule set out by the county for the general plan process sticks.

“The plan covers so much stuff we really need to keep it on schedule,” he said.