How Water Data Traced E. coli at Cumberland Gap to a Campground Septic System

Sampling water at Station Creek. NPS / Emma Brinley Buckley.

In 2008, scientists with the National Park Service's Cumberland Piedmont Inventory & Monitoring Network (CUPN) noticed that E. coli at one of their water sampling sites in Cumberland Gap National Historical Park was too high — a worrying trend.

They had been sampling on the second Tuesday of every month for the previous two years. Water quality is one of the park's "vital signs," the measurements scientists use to judge the health of the whole ecosystem, and alongside E. coli they record temperature, pH, specific conductance and turbidity. The number that kept standing out was bacteria at the Station Creek site.

Why it mattered

E. coli normally lives in the guts of people and other warm-blooded animals. Most strains are harmless, but some make people sick through contaminated food or water or contact with infected people or animals, and the bacteria reach streams when feces gets into the water.

Nobody usually swam in or drank from Station Creek at that spot, but it sits near the park's only developed campground. High counts were a possible risk to visitors — and, depending on the source, to the stream itself: human or animal waste can add excess nutrients, setting off eutrophication and making the water unlivable for aquatic plants and animals. Fixing it meant first finding where the waste came from.

Two suspects, two patterns

Station Creek, like many park streams, is normally pristine and rises inside the park, so the contamination had to be coming from inside too. Bears, deer, horses, raccoons and possums all live in the woods; so do campers, and the park operations that serve them. Luckily, the team had two full years of reliable data.

Possible suspects: black bears and white-tailed deer live throughout the park. NPS.

What the data showed

Across the record, E. coli climbed in late spring, peaked in summer, tailed off through autumn and was lowest in winter. Discharge — the volume of water passing a point in a set time — was highest in winter and early spring, exactly when E. coli was lowest. That ruled out wildlife washing in with the rain.

Discharge (blue) and E. coli (red) at the Station Creek site: flow was highest when bacteria were lowest, pointing to a source inside the park. Adapted from Meiman 2009.

What did match was visitors. Summer is a drier time in the park and also its busiest, and a strained wastewater system would show exactly that pattern. One of the highest readings came just two days after Labor Day 2008. The team looked to the nearby campground's septic system, which park managers already knew needed replacing.

The fix

The results gave that job urgency. Wilderness Road Campground, host to thousands of visitors every year, was due for an upgrade, and when managers proposed a full overhaul of its wastewater system, CUPN's data helped show it was needed. Old sewer lines were replaced and septic tank and leach field sizes were rethought so the system would not be overloaded — which also meant fewer resources spent on maintenance emergencies.

Comfort stations at Wilderness Road Campground. NPS.

A decade later

CUPN has kept sampling Station Creek for more than a decade since. Bacteria and other measures still exceed limits occasionally, but E. coli has never been as high, or high as often, as before the upgrade. And the relationship with rain has flipped: bacteria now rise and fall with precipitation, as expected when pollution comes from scattered sources. The same monitoring that caught the problem showed that the solution worked.

Sources

Rewritten from the National Park Service article "I&M Water Quality Data Helps Cumberland Gap National Historical Park Address Aging Infrastructure," researched and written by Olivia Porter, Scientists-in-Parks intern, NPS Inventory & Monitoring Division (public domain), in hubnx's own words.