Lake Auburn is one of the few water systems in the country that don't need to be filtered because it has high water quality. But that's at risk.
In this April, 22, 2019, file photo, a man gets his boat ready to launch in Lake Auburn to go fishing. Credit: Andree Kehn / Sun Journal via AP

This story is part of Maine Public’s series “Climate Driven: A deep dive into Maine’s response, one county at a time.”

You might not know it, but drinking water systems can develop a reputation.

“Lake Auburn is one of our kind of jewels, if you will, of the drinking water systems,” said Holly Ewing, a professor of environmental studies at Bates College.

Ewing said Lake Auburn, which provides drinking water to 40,000 people in Lewiston and Auburn, is one of the few water systems in the country that don’t need to be filtered because it has high water quality. She has studied the lake for more than a decade, and is standing on a grassy shore near the marsh where Townsend Brook flows into the lake.

“So this is an area even though, you know, we’re standing here listening to redwing blackbirds and other birds here in the spring, we have substantial concerns about the water quality, what’s happening in terms of land use upstream of here, because this is one of the major conduits of water, and therefore nutrients, pollutants of any kind, into the lake,” she said.

When excess phosphorus and other nutrients enter the lake, they can cause algae blooms. A bloom that occurred a decade ago depleted so much oxygen that it caused a fish die-off. Another bloom in 2018 prompted the water district to apply an alum treatment to remove phosphorus and buy time to implement more protections. But that time is running out, Ewing said.

“Water quality improved dramatically with the alum treatment. And now it’s just been gradually getting worse,” he said.

And Ewing said climate change is playing a role. Winter ice cover on the lake is diminishing, and water temperatures are rising. That means algae has more time to grow. And there are more extreme storm events that dump sediment and runoff into the lake, which further degrade water quality.

“So we’re really at a place where the system is very vulnerable.”

Ewing isn’t just worried about the effects of climate change on the lake. The city of Auburn plans to open up more land in the watershed to development through new zoning standards.

“So the reason we’re doing everything isn’t about development,” Auburn Mayor Jason Levesque said. “It’s about managing climate change, which is a reality.”

Levesque has never before highlighted climate change as a motivation for the zoning changes. But he has set a goal to develop 2,000 new housing units by 2025.

The city recently commissioned a study to examine Lake Auburn’s water quality and different management scenarios. The recommendations included redrawing a portion of the watershed boundary to remove 148 acres and adopting updated septic system standards. Both of these would open up new areas to development. Levesque said those changes, along with the city’s plan to triple the minimum lot size, will allow responsible home construction and still protect natural resources.

“It’s OK to have a house,” he said. “As long as you don’t have the negative effects. And we’ve covered all of that, through low-impact design and a modern septic system.”

But the same study also concluded that there is no net environmental, social or economic benefit to expanded development in the watershed. And the city of Lewiston agrees.

It’s suing the Auburn Water District to block changes to the watershed boundary. Lewiston Mayor Carl Sheline declined to comment on the lawsuit, but criticized Auburn officials for prioritizing development over clean drinking water, at a time when the effects of climate change are placing additional pressures on the lake.

“On a municipal level we won’t be able to affect the climate around Lake Auburn,” Sheline said. “And since we can’t control that, what we do matters even more. We can control development around Lake Auburn and the fact of the matter is development around Lake Auburn is going to be bad for water quality in the lake.”

And if water quality declines beyond a certain point, costs for drinking water customers will go up.

Currently, raw water from the lake is pumped through a series of massive pipes at the Auburn Water District’s treatment facility. It undergoes several chemical treatments before it’s delivered to users. Manager Chris Curtis said if the lake needs filtration, drinking water would essentially require a new recipe — and a whole new facility.

“It’s a completely different treatment,” Curtis said. “Different staffing. And it’s significant capital expenditure.”

It’s estimated a new treatment facility would cost between $45 and $60 million to build, plus up to $2 million in annual operations costs.

Watershed manager Erica Kidd said protecting the lake’s water quality from runoff and other pollution involves replacing culverts, acquiring land, reviewing permits, and educating the public. But she said it’s a challenge when the watershed is spread across five towns: Auburn, Turner, Hebron, Minot and Buckfield.

“It’d be easier if there was, you know, one big industrial user, that was the polluter, and then you’d go work with them and that was it,” Kidd said. “But this is a combination of several small things spread out over pretty good land mass and over time.”

At the northern end of the lake, upstream water flows into an area called the Basin, then pours over a dam. It’s the largest input to the lake, said Ewing, the Bates professor. This place, she said, illustrates how actions in each town in the watershed — large and small — collectively influence Lake Auburn’s future, especially in the face of climate change.

“That’s true in how many parts of our lives, you know?” Ewing said. “A small act of kindness can make your day a lot better. A small act of aggression can make your day a lot worse. Small acts of conservation collectively add up to a lot of conservation, small acts of protection collectively add up to a lot of protection.”

Because of litigation, it’s unclear whether Auburn’s plan to expand development in the watershed will move forward. But the developer who owns the 148 acres that would be removed if the boundary is redrawn is hoping to construct 1,100 housing units.

This article appears through a media partnership with Maine Public.