HALLOWELL — Hall-Dale High School senior Lily Drouin-Scease showed up to the Hallowell Reservoir, locally known as The Res, at just past 8 a.m. Thursday, flustered and convinced she was late. Nobody else was in the parking lot.

She frantically called Rosemary Presnar, the chair of the Hallowell Conservation Commission, hoping she’d still be able to tag along on Thursday’s survey of the Vaughan Brook watershed. They were gathering at The Res, a dammed pond that essentially marks the brook’s headwaters and serves as one of Hallowell’s most popular summertime swimming holes.

Turns out she was just an hour early.

Drouin-Scease was one of four volunteers who inspected dozens of points along the Vaughan Brook watershed Thursday with the help of professionals from Ecological Instincts, a Manchester-based environmental consulting and planning firm. The goal was to identify places in the watershed where runoff could affect the quality of the stream — a requirement for securing long-term stream remediation funding.

Drouin-Scease spent four months last year at the Maine Coast Semester at Chewonki, a hands-on environmental science program for high school juniors and seniors. There, she got hooked on stream ecology.

“We did a lot of outdoor field research, and I really liked the stream ecology lab,” she said. “And then I saw the Hallowell Conservation Commission was doing something like that over the summer, and I was interested in exploring that more.”

Jen Jesperson, the principal and senior scientist at Ecological Instincts, partnered with Drouin-Scease to form one of the four teams who scouted the watershed. With others assigned to the watershed’s other corners, the pair stuck to surveying The Res and its immediate surroundings — beach areas where banks had washed out, packed gravel trails around the water that could exacerbate runoff, and the dam that blocks the pond from flooding the wetlands and woods downstream.

As the pair walked up to their first survey site on the bank of the pond, Jesperson took Drouin-Scease through the paperwork of the survey and what they’d be looking for throughout the day.

“Pet waste, toxics, trash, soil erosion,” Jesperson said. “Soil erosion’s a big one because it’s sediment that can impact critters in the stream, but it also carries nutrients like phosphorus and nitrogen that lead to algae.”

Vaughan Brook runs for about 3.7 miles through parts of Farmingdale and Hallowell, passing through Vaughan Woods before it empties into the Kennebec River. In all, the stream drains about 5.9 square miles, including The Res and a small portion of Augusta near the heavily traveled Western Avenue interchange with Interstate 95.

For years, Vaughan Brook has failed water quality tests. Testing in the Vaughan Woods portion of the brook over the past 13 years has repeatedly missed the state’s mark for supporting aquatic life. Only one test in the watershed — at The Res in 2017 — has passed state standards in the past 10 years, and even then it didn’t pass muster for certain kinds of insects.

The brook is listed as “threatened” under the Maine Department of Environmental Protection’s Nonpoint Source Priority Watersheds List because of the risks development poses for the health of the stream. This designation helped the Hallowell Conservation Commission secure state grant funding for Thursday’s survey, which in turn will help the commission secure funding to implement a long-term management plan for the watershed.

As the pair walked along the bank of The Res, Jesperson was already running through what recommendations might go into the plan: a thickened brush barrier along the edge of the water to slow erosion and a cleaned-up rock barrier to divert water away from a trail.

Ecological Instincts is one of the only firms in Maine that develops these kinds of long-term stream management plans, which are usually funded by grants under the federal Clean Water Act and are required for the bigger implementation grants the conservation commission will need to continue their work down the line.

Jesperson said she has also recently worked on surveys for Whitten Brook in Skowhegan and Penjajawoc Stream in Bangor — both of which are classified by the state as “impaired” streams, an even more serious level of environmental concern than Vaughan Brook.

In fact, 168 streams across Maine fit into these two classifications, according to DEP’s March 2023 list. Many “impaired” or “threatened” streams are affected by highways or intense agricultural activity nearby, while others are affected by invasive species or bacteria.

About a quarter of these streams, including Vaughan Brook, are specifically affected by urban development — the more buildings, roads and paths in a watershed, the more vulnerable it is to stormwater runoff.

The only way to know exactly where to remediate, though, is to survey the watershed, finding spots where runoff could be mitigated, like The Res beach area. Jesperson said that kind of effort usually runs better with volunteers on the team.

“We always try to use volunteers because, for one, it gets them out to understand what we’re doing and gets them invested in it,” Jesperson said. “It’s raising awareness for what we’re doing. It’s one thing to read a report about what we found, but it’s another thing to actually do it, and understanding that’s what’s running into there and that’s what’s impacting the stream.”

Jesperson said she’s not going to manage the watershed forever. It’s for the residents of that place — like Presnar and especially Drouin-Scease, who said she wants to study environmental science in college — to implement the plan and keep the stream habitat clean.

The Hallowell Conservation Commission will survey the length of the stream in August to complete this phase of the project and apply for more grant funding for its implementation.

Drouin-Scease said she hopes to tag along.