Skagit County commissioners are poised to label certain neighborhoods on the county’s west end as areas of special concern because their septic systems could contaminate shellfish and other wildlife.

Failing septic systems are a source of fecal coliform, a bacteria found in human and animal waste that indicate a possible threat to human health. Excessive levels of fecal coliform led to closures of the commercial shellfish beds in Samish Bay twice in six weeks this spring.

The county Public Health Department has proposed 10 areas of concern, which have varying numbers of septic systems with no inspection records.

The areas of concern are part of a new county on-site sewage program that requires inspections of septic systems every one to three years. A new state law required the county to develop the program.

The commissioners held a public hearing on the proposed areas on Tuesday.

Ed Stauffer, president of the Alger Watershed Association, said the on-site sewage program stigmatizes rural residents who rely on septic systems. He cited reports that said that manure spreading and wildlife are more likely to cause spikes in fecal coliform levels.

“I would like the board ... to relieve the homeowners of the rural areas of Skagit County of the burden of falsely accusing us of polluting the waters of the county,” Stauffer said.

The commissioners said they didn’t intend to falsely accuse anybody of polluting.

“I don’t feel that we’re actually pointing the finger and blaming septics for the problems we’re having,” Commissioner Don Munks said.

He agreed there was evidence that wildlife is to blame for some of the coliform in local streams. Officials from the Skagit Conservation District also suspect that hobby farmers — landowners who have a small number of livestock — are contributing to coliform levels in the streams and shellfish beds.

The septic program is valuable, county and state health officials said, because it will provide more information about just how large a role septic systems play in polluting the water.

County officials hope to inspect and repair all septic systems in five coastal “marine recovery areas” and in five other “sensitive areas” that drain into coastal waters by 2012.

“People need to take responsibility for their sewage, whether they’re in town ... or if they are out in the rural area,” county Environmental Health Supervisor Corinne Story said.

The commissioners are scheduled to vote on an ordinance adopting the areas on Sept. 16.

Ralph Schwartz can be reached at 360-416-2138 or .