On a pontoon boat on Oak Hollow Lake in Guilford County, Daniel Morrill gently removed a leech from his leg.
He and a few volunteers had just slipped out of waist-deep murky water, shedding sturdy gloves and wringing out their shirts. Morrill is a fisheries biologist with the North Carolina Wildlife Resources Commission. He was planting spatterdock, a leafy, half-submerged aquatic plant.
Planting spatterdock requires some digging and splashing. Despite the soft earth under the lake, it’s difficult. If a planting fails, the spatterdock’s bulb-like roots will float back up to the surface of the water and bob spitefully.
Oak Hollow Lake is one of two major reservoirs providing water for the residents of High Point in central North Carolina. For the past 15 years, the NC Wildlife Commission and a team of volunteers have periodically visited this lake and planted spatterdock, water willow, and pickerelweed, among other species.
“There pretty much wasn’t any aquatic vegetation here when we started,” said Morrill. “A lot of our reservoirs are man-made, dammed-up creeks, so the aquatic vegetation that used to grow here is so deep and in the middle that no light that can reach it.”
Along the edges of natural water bodies, shoreline plants grow. But in man-made ones, there isn’t anything to stop sediment from crumbling into the lake. There also isn’t any way to filter runoff.
“Sediment catches mud, and then the mud acts like biscuit dough, and pollutants stick to that. And then you've got this big thing cooking that allows all sorts of algae to grow,” said William Frazier, who is a Wildlife Commission volunteer and bass fishing expert.
Organic materials like mud attract and bind contaminants. As the heavy particles settle, pollutants end up accumulating in the lakebed.
“The water quality issues in our waters are due to upstream impacts. What you do on the land will impact what goes into the water,” said Mark Fowlkes, who is an aquatic habitat coordinator with the Wildlife Commission.
Oak Hollow Lake is in an urban area with some agricultural land and a large golf course. It gets its water from runoff and rain. When it lacked shoreline plants, there was nothing between it and fertilizers, pesticides, and heavy metals from runoff.
From the pontoon, it was easy to see where the lake gets hit with runoff. The water is murkier, and the mud more disturbed. The Wildlife Commission targets these areas in the lake for planting.
“It’s a municipal reservoir, so there's a lot of development around it already, as we all know in North Carolina, that's only increasing right now. A lot of our reservoirs will see more and more of these kinds of issues,” Morrill said.
Along with preventing bank erosion, aquatic plants absorb nutrients from runoff that would otherwise cause harmful algal blooms. The Wildlife Commission’s team has seen the lake’s health improve in real time.
“Pickerelweed is a really good one at absorbing nutrients, so much so that sometimes we'll plant it and early on it'll do fantastic, and then after a couple of years, not quite as lush as it used to be,” Fowlkes said. “My guess is that it's kind of absorbed some of the nutrients around there.”
Before it was Oak Hollow Lake, parts of the land were dairy farms. In the early 20th century, a gold mine ran under where the lake is now (occasionally, it ‘burps’ when underground bubbles are released). There are also major petroleum pipelines running beneath the lake.
Before all of that, the land was a riverine system, complete with flowing streams, floodplains, and wetlands.
“We’re constructing a tree museum,” Frazier said, referencing lyrics from “Big Yellow Taxi,” Joni Mitchell’s anti-development anthem. “It’s nuts.”
Plantings in the Triangle just finished last week, with more across the state coming up. To volunteer, visit NC Wildlife's Facebook page.