Baltimore County Executive Johnny Olszewski, Jr. speaks at Cox’s Point Park in Essex on Monday morning about the county’s efforts to address midge infestations on Back River by spraying larvicide. The flying insects are often found in bodies of water polluted with high levels of nutrients. As a result, the discussions about midges are “directly linked” to the nutrient pollution flowing from the troubled Back River Wastewater Treatment Plant, Olszewski said. (Christine Condon)

When the insects first started appearing en masse near the docks of Weaver’s Marine Service in Essex around 2008, owner Sam Weaver wasn’t sure what they were.

“We didn’t know,” he said. “We were spraying in the air. People were spraying for mosquitoes and all kinds of things.”

In truth, the insects were midges — tiny aquatic flies that occur in their greatest densities in nutrient-rich bodies of water.

Whether it comes from fertilizer runoff, septic systems, car exhaust or other sources, nutrient pollution is one of the greatest threats to the health of the Chesapeake Bay. By hastening the growth of algae, these nutrients — including nitrogen and phosphorous — rob the estuary’s waters of critical oxygen, harming marine life.

In Weaver’s case, pinpointing the source of at least some of those nutrients isn’t challenging. Just across the river from his marina sits the Back River Wastewater Treatment plant, its silo-esque structures poking above the tree line.

The midge issue is hardly unique to the waters surrounding the Back River plant, which is operated by Baltimore City’s Department of Public Works and located in Baltimore County. But the city is currently facing lawsuits, filed by the state and a nonprofit group, over the plant’s unauthorized discharges of nutrients and bacteria into Back River, and similar issues at its second plant along the Patapsco River. Three weeks ago, the state took charge of the Back River plant, arguing that conditions there were continuing to decline.

Desiree Greaver, a Rosedale resident who is project manager with the Back River Restoration Committee, collects water samples from the Back River to test on April 5. The committee has been collecting samples weekly since February. (Kevin Richardson / Baltimore Sun)

Against that backdrop, a protracted political battle over midge remediation came to an end this month. In early April, the Baltimore County Council approved a roughly $7.5 million contract for a larvicide to be sprayed via helicopter onto the waters of Back River over the next five years.

The Maryland Department of Agriculture has pledged $1.6 million for the first two seasons of spraying — about half the cost for those years.

“We know the nutrient load from the plant is a direct contributor to the midge challenge here,” Baltimore County Executive Johnny Olszewski Jr. said during a news conference Monday at Cox’s Point Park in Essex, which overlooks the wastewater treatment plant.

As a result, Olszewski said, there ought to be conversations about “shared governance” of the plant, perhaps between the city and county.

Midge remediation efforts have faced political headwinds in years past. In 2016, Maryland Gov. Larry Hogan asked then-County Executive Kevin Kamenetz to foot half of the bill for a midge treatment program on the river, offering state funds for the remainder. But the proposal never came to fruition.

In 2017, Hogan signed an executive order calling for a pilot study for midge remediation. By late 2021, the county had tested the idea, and determined aerial application was the best course of action, according to documents presented to the County Council.

Meanwhile, businesses like Weaver’s marina have paid the price, Weaver said Monday. After the marina paid for new docks in the wake of 2003′s Hurricane Isabelle, business began to slow when the midges grew in number. At their worst when temperatures warm, the midges cause plenty of frustration along the shore, he said.

“It’s a Band-Aid on a bullet hole,” Greaver said of spraying to control the nuisance insects. “We need to fix the source of the issue. Once this is under control, and there’s no more illegal discharges, then that’s when it makes sense to treat the midges.” (Kevin Richardson / Baltimore Sun)

“If you open your mouth, your mouth’s full of them. You get them in your eyes, your ears,” Weaver said. “We ride golf carts on our pier. We have to wear a full-face helmet to ride out.”

The first spray of the larvicide took place April 11, and four more are expected at four- or five-week intervals through the fall, depending on midge population levels. The helicopter will spray a naturally occurring bacteria called Bti, which is nontoxic to humans and other wildlife, and it will sink to the bottom, killing larvae that feed on organic material on the river bottom.

Meanwhile, concerns about the discharges from the wastewater treatment plant persist, said Desiree Greaver, project manager for the Back River Restoration Committee, which has been collecting weekly water samples from Back River since February.

“It’s a Band-Aid on a bullet hole,” she said. “We need to fix the source of the issue. Once this is under control, and there’s no more illegal discharges, then that’s when it makes sense to treat the midges.”

On a recent trip aboard the Lilly B, a small, pearly white motorboat, Greaver donned blue gloves to collect her samples.

“It’s unfortunate that it’s gotten to this point,” she said, referring to the state’s takeover of the wastewater plant, which Baltimore subsequently challenged in court. “There’s a lot of this that could have been prevented.”

Last week, Greaver’s samples, processed through local nonprofit Blue Water Baltimore, told a concerning story. One of the samples from the river showed fecal bacteria levels more than 180 times a state safety threshold, while several others taken on the same day at other locations were within normal ranges.

In a statement Thursday, the state Department of the Environment acknowledged that the plant had released “some recent elevated levels of bacteria and solids in recent days.”

“However, they do NOT appear to be at levels that would explain the reported levels for the river,” read a statement from department spokesman Mark Shaffer.

The department plans to review the samples from the nonprofit, Shaffer said. The department also analyzed solid materials found floating in the river, which some had feared was sewage.

The material is not raw sewage, and did not contain any “undigested byproducts” or live bacteria, Shaffer wrote. Still, it contained several “non-living shelled amoeba,” evidence that the material could be coming from the wastewater treatment plant.

Blue Water Baltimore stands by its analysis of the samples, said the organization’s Baltimore Harbor waterkeeper, Alice Volpitta. In cases like last week’s, the bacteria sample “lit up like a Christmas tree” when analyzed by the group’s trained testers, Volpitta said, leaving little room for interpretation errors.

“I know that MDE and Baltimore City are trying to provide information to the public to put their minds at ease,” she said, “but at the end of the day those high bacteria levels are coming from somewhere.”

Whether the contamination is coming from the wastewater treatment plant or flowing from Back River’s tributary Herring Run, officials owe it to the public to explain more clearly when the water is safe for recreation, Volpitta said.

“What this all really boils down to is that people want to know whether or not it’s safe to come into contact with the water,” Volpitta said.

She added that her group plans to conduct additional sampling, this time alongside Maryland Department of the Environment staff, to obtain more information.

Baltimore Sun reporter Ngan Ho contributed to this article.