AUBURN — The City Council moved forward with two more proposed changes to Lake Auburn watershed rules Tuesday after signaling earlier this month that mediation with the city of Lewiston had failed.

Auburn officials said Tuesday that both proposals continue the city’s effort to create “transparent, science-based ordinances,” that will reduce the overall development potential in the watershed. They’re also hoping that taken together, they can potentially be put in place in upper watershed towns.

In a first reading, the council approved a prohibition on any new septic systems being installed within 300 feet of the lake, as well as establishing a “conservation and natural resource protection” zone in the areas of the Lake Auburn watershed currently located in the agricultural zone.

Both votes were 5-1, with Councilor Belinda Gerry opposed. Councilor Steve Milks was absent.

According to Eric Cousens, current rules allow systems to be installed within 300 feet if soil criteria are met. A separate update to the city’s septic design standard would make it easier for new systems to utilize alternative soils in designs, resulting in more buildable lots. However, staff has introduced other measures, like the 300-foot buffer, as well as larger minimum lot sizes, in order to alleviate development concerns.

Still, some residents remain concerned over the proposals. During public comment, Bruce Rioux said the city should reimburse ratepayers of the Auburn Water District for the cost of legal fees associated with the lawsuit between the water district and Lewiston.

He argued that the Auburn Water District became the defendant rather than the city of Auburn, which had proposed the watershed changes at the heart of the lawsuit. Rioux has long argued that the proposed changes are not about water quality concerns, but about benefiting watershed landowners.

Cousens said Tuesday that lake water quality is considered “at-risk,” and that current ordinances “have not prevented the need for in-lake treatments.” He said the proposed changes will be easier to understand, better for the environment and water quality, and reduce development.

Earlier this month, the city issued a news release stating it planned to move ahead with changes to Lake Auburn watershed rules after attempts to resolve the lawsuit through mediation had failed.

Among the proposals listed were the septic design changes and a revised watershed boundary line.

Also included in the proposals taken up Tuesday was reclassifying roughly 4,000 acres of land in the agricultural zone and placing it into conservation. According to a staff presentation, “consultants have identified agriculture, specifically animal farms, as a significant threat to water quality.” The council will send the issue to the Planning Board to consider.

Both proposals voted on Tuesday came out of a recent peer review of a watershed study completed by FB Environmental, which has been the basis of much of the city’s proposed changes.

Cousens said the city will also be asking the Lake Auburn Watershed Protection Commission to take “a more active role in ordinance-related permit reviews,” and will ask the council to consider a septic inspection program, requiring systems within the watershed to be inspected every five years.

Councilor Dana Staples said he’d like the Planning Board to take a look at the new conservation zone not only for the watershed, but also other parts of the city, including Mt. Apatite and the riverwalk area.

“I think this is a good step forward for the city,” he said.