AUBURN – A neighborhood’s effort to relax some septic system rules around Lake Auburn will get a public hearing Aug. 14.

The effort could harm the Twin Cities’ water supply, according to representatives from the Lake Auburn Water Protection Commission. They met with Auburn councilors and the city’s Planning Board on Monday night to explain why it’s not a good idea.

“Our ordinances are helping to keep the watershed clean, and that’s better for all of us,” Auburn Water District Superintendent Normand Lamie said.

The Lake Auburn area has the highest standard for septic systems in the state, according to Dan Bilodeau of 207 North Auburn Road.

Bilodeau’s group, the Lake Auburn Watershed Neighborhood Association, is pushing to get those standards relaxed.

State rules require septic system leach fields be a minimum of 15 inches deep in known watersheds.

Auburn’s ordinance requires the septic systems be buried at least 36 inches deep in the Lake Auburn Watershed.

Bilodeau said it’s an attempt to keep lots from being developed around the lake.

“A 36-inch deep pit doesn’t do a better job of getting rid of effluent,” he said. It actually works worse in gravely soil, like that underneath the land around Lake Auburn.

“The end result is that there are very few areas that have soil that will allow a 36-inch deep pit,” Bilodeau said. That means no development and less runoff from homes and driveways.

“It’s a way to get rid of nonpoint water pollution, but it doesn’t do a thing for septic systems polluting Lake Auburn,” he said. “Properly functioning septic systems are not the problem.”

But Lamie said the deeper septic systems are better for water quality. He pointed to 108 shallower septic systems in the watershed that failed. They were built before Auburn’s ordinances were in place, and were allowed as nonconforming uses. Four of the replacement systems, built just as shallow, have failed as well.

Another 35 septic systems that were built to Auburn’s standards have yet to fail, he said.

The Planning Board has scheduled a public hearing on the issue at the Aug. 14 meeting. They’ll make a recommendation, and it will come back to the City Council for a final vote later this year.