This story has been edited from its original version.
Nearly 29 miles of Mountain Run, from Lake Pelham east to its confluence with the Rappahannock River, is “benthic impaired.”
The stream’s aquatic life is under stress, according to the latest data collected 2015-2021 by the Virginia Department of Environmental Quality that added 4.6 new miles along Mountain Run into the benthic impaired category.
The Culpeper County stream has been on the state’s impaired waters radar since 1996 for fecal bacteria and for benthic impairment since 2008. The latest monitoring data found increased PCBs in fish living along that stretch of stream, first detected in 2006. Mountain Run is part of the Chesapeake Bay watershed.
PCB impairments in Mountain Run increased in the 2016, 2018 and 2020 assessments. PCBs are an extremely persistent group of toxic, organo-halogen compounds that cause cancer.
They readily accumulate in the tissue of fish, according to the U.S. Environmental Protection Agency. High concentrations can pose health risks to humans.
In 2016, an fish advisory listed a single species for Mountain Run, the American eel, and recommended people limit consumption to no more than two meals of it per month, according to David Evans, nonpoint source coordinator in the Department of Environmental Quality’s Northern Regional Office in Woodbridge.
Eels are listed because they live longer and are higher on the food chain, thus consuming (and bioaccumulating) more PCBs over their lifespans than other fish, he said. However, other fish in Mountain Run besides eels have high PCB levels as well, Evans said.
DEQ, in consultation with a multi-agency work group it is leading, is drafting a plan to continue to address benthic health and bacteria in the Mountain Run watershed, including Mountain Run Lake, which is unsafe for swimming.
It will be up to the EPA to approve that plan. By spring of 2023, the work group will then apply for federal funding to implement measures to make Mountain Run healthier.
Prime factors contributing to Mountain Run’s impairment include the proliferation of residential septic systems in high-growth Culpeper. Agricultural and residential runoff, especially after severe rains—as have become the norm—also pollute Mountain Run.
All that is revealed by recent discussions among the work group, which aims to advance solutions to the environmental issue. The group met virtually May 11 to discuss DEQ’s latest findings, which are based on six years of on-site testing.
The Culpeper Soil & Water Conservation District, a local member of the work group, has long been involved in implementing best management practices for area streams. Also contributing to the project are Friends of the Rappahannock, the Rappahannock Rapidan Regional Commission and the town and county of Culpeper.
The conservation district’s Greg Wichelns observed at the recent meeting that a slide showing DEQ’s best management practices for benthic health did not include making connections to the town’s municipal sewer system. Dave Evans, the work group’s leader, said recommendations would be forthcoming to make sewer connections in areas near the town’s treatment plant.
More than 6,500 septic systems in the affected watershed are not connected to wastewater pipes, DEQ found.
To improve local water quality, 1,790 septic system pump-outs, 900 repairs and more than 600 replacements are recommended.
The group is also using pet-waste stations to reduce fecal bacteria in the stream. DEQ estimated more than 8,000 dogs live in the Mountain Run watershed, which also has six licensed kennels.
Tree planting, reforestation and creating wetlands will be done in response to the DEQ report, which detected E. coli bacteria in Moutain Run as it flows through the town’s Yowell Meadow Park. That reflects poor health among macroinvertebrates, the lowest aquatic lifeform, which indicate stream health over long periods of time, DEQ said.
Mountain Run aquatic life is under stress due to the stream’s state of dissolved oxygen, pH, total phosphorus, total nitrogen, ionic strength, dissolved metals, and its total habitat and relative bed stability.
Benthic health scores less than 60 are considered impaired. Spring samples along Mountain Run in Culpeper were 43.06, a low point for the watershed, which had an average impairment score of 50.14.
DEQ ambient water-quality monitoring of the run occurs monthly or bimonthly, but most likely during base or low flow, given the infrequency and safety associated with storm sampling, the report said.
“In order to have a healthy macroinvertebrate community, a stream must have a suitable habitat,” DEQ said. “Sensitive benthic macroinvertebrates require spaces between stream substrate that are free of sediment and stable during storm events.”
Wichelns noted that some stream segments (Jonas Run and Flat Run) have very limited data points, and said that DEQ should be cautious in making conclusions about seasonal patterns. Roland Owens of DEQ noted the complexity and time requirements for benthic analysis limit observations.
Wichelns suggested that DEQ identify likely sources of bacteria in developed areas in and around the town of Culpeper, so stormwater-management best management practices can be made where it will most reduce bacteria.
October Greenfield, the upper river steward of Friends of the Rappahannock, said its bacteria sampling plan for Mountain Run is under development, as well as sample plans for the Rush and Lower Hazel rivers.
Citizen science volunteers and FOR staff will participate in sampling efforts being done with the Alliance for Chesapeake Bay, Greenfield said. Additional sampling in Mountain Run should help to identify areas with high bacteria levels in stormwater runoff.
Culpeper Town Planning Director Ben Holt shared information about the town’s plans to buy and install another 11 pet-waste stations along Mountain Run and its tributaries this summer. Several stations are already in place with support from FOR, Holt said.
Michelle Edwards said an Upper Rappahannock Watershed Plan being prepared by the Rappahannock Rapidan Regional Commission will include a data application, under development by the Chesapeake Conservancy, that will identify the type and location of best management practices that will achieve the greatest benefits.
Richard Jacobs of the Soil & Water Conservation District said many homeowners associations have objected to having “no mow” zones and other environmentally-beneficial practices, over landowners’ concerns about mosquitos and wildlife.
Jacobs seconded the call for more public education and outreach. Addressing untreated storm drains, improving existing stormwater measures, adding filtering and infiltration features to dry detention ponds and converting them to wet ponds would all benefit water quality, he said. Jacobs advocated leaving a grass buffer when mowing around wet ponds.
He said schools and other public buildings play a part in managing pollution that gets into Mountain Run.
Wichelns said the biggest water-quality concern comes with the first flush of runoff during a storm. Evans agreed, saying that slowing or halting infiltration at the beginning generally helps water quality the most.
In follow up correspondence, Evans shared that the benthic stressor analysis identified sediment and nutrients as probable stressors to the benthic community.
"Development, whether it be for residential or commercial activities, increases impervious surfaces in the watershed, which leads to increased runoff and possibly increased nutrients (such as from fertilizer application). This runoff can carry sediments and excess nutrients into Mountain Run, causing stress to the benthic macroinvertebrate community," he said.
Municipal wastewater is not a source of these pollutants, but could be a source of bacteria, Evans said. The Town of Culpeper’s VPDES permit limits bacteria in its wastewater treatment facility effluent to levels below the E.coli bacteria criterion, he said.