The Madison (Wis.) Metropolitan Sewerage District has monitored the chemistry of the effluent leaving its Nine Springs Treatment Plant since the early 1940s. In 1983, the staff research biologist began shocking fish and looking at aquatic insects in the receiving streams as another way to monitor the discharge and protect the environment.
The district’s effluent quality always met EPA and Wisconsin Department of Natural Resources (DNR) standards. In 1986, the district doubled the size of the plant, increasing retention time to lower BOD and TSS, adding nitrification, and switching from chlorination to UV disinfection. As effluent quality improved, pollution-intolerant aquatic insects and fish began moving upstream.
Jeff Steven joined the district biomonitoring program in 1981 while finishing his master’s degree in entomology at the University of Wisconsin. Today, as district research biologist, he is in charge of the biomonitoring program, but also takes monthly water samples at the two receiving streams, then has them analyzed in the lab for 18 parameters ranging from metals and nutrients to sulfates and alkalinity.
The scientific water chemistry data is indisputable evidence that the district meets or outperforms EPA and DNR limits for point-source discharge. Its biomonitoring program puts the cork in the bottle.
Aquatic sampling
Two watersheds affect the Nine Springs plant. Initially, it discharged to Badfish Creek in the Yahara River watershed. As the city expanded, the plant accepted wastewater from the city of Verona, 10 miles west in the Sugar River basin. To return some of that water, Nine Springs discharges 40 mgd to Badfish Creek and returns 3 mgd to the Sugar River via Badger Mill Creek.
April and October are the prime months for sampling receiving streams for aquatic insects. Steven does it all in one day through qualitative “kick” samples. He looks for fast-moving water over riffle (rocks and gravel). “I stand upstream, kick the streambed, and hold my D-frame net downstream,” says Steven. He takes three kick samples per sample site. There are four sample sites on Badfish Creek, two on Sugar River, and three on Badger Mill Creek.
Collected material is rinsed within the net, put into bottles, preserved, and brought back to the laboratory for sorting and identification. Steven selects 150 insects from each sample, then puts them under a microscope to identify the species. “I’m always happy to see species that are more sensitive to pollution, as they confirm the quality of our effluent,” he says.
Fish sampling
There are three fish sampling sites on Badfish Creek, two on Sugar River, and two on Badger Mill Creek. The team shocks four 100-yard sections per site, using a walk-along stream-shocking boat. One person pulls the 6-foot-long flat-bottom craft, and two walk in front shocking with electric probes on 6-foot-long fiberglass poles. Direct current from a gasoline-powered generator pulls fish toward the probes. All floating fish within the 100 yards are scooped up and put in the boat’s wet well to recover.
In Badfish Creek, Steven has collected 45 species since shocking began in 1983. He collected 27 species in Badger Mill Creek and 32 species in the Sugar River since shocking began in 1994.
“We identify species, weigh and measure some, and release most of them,” says Steven. “We keep a few minnows for positive identification.” He also checks for lesions, skin problems, and deformities, but is interested mostly in the types of fish.
“Quality water attracts a diverse population of predators and minnows,” he says. “We like to see northern hog suckers and mottled sculpin because they are pollution-intolerant species. Brown trout are good, too, as the DNR stocks them in Badger Mill Creek.”
Tank testing
Another way Steven monitors effluent is by pumping it through two 55-gallon fish tanks, one in his office and the other next door in the public education display room. Bluegills and green sunfish in the tanks appear to be doing well. The tanks even served as a visual alarm once, when Steven noticed the water a turbid brown. Looking outside, he saw a broken sweep arm on a clarifier. At about the same time he called the director of maintenance, the plant’s SCADA system identified the problem.
Steven initially did toxicity testing for the plant’s NPDES permit. “The process involved raising water fleas and fathead minnows,” he says. “Eventually, we discovered that sending the water samples to independent laboratories was less expensive.”
Nine Springs has a solid relationship with the state Department of Natural Resources, sharing data and working together. “I am able to show how the plant meets EPA and DNR standards by what we collect in the field,” says Steven. “Those agencies are always looking for different ways to regulate point-source discharges, and we feel they will use aquatic insects and fish a lot more in the future.”
Should the time arrive, Steven recommends that smaller communities use a consulting firm to monitor their receiving streams. “The cost of the biomonitoring program is minimal, but you need a biologist on staff,” he says. “I don’t know of many treatment plants except ours that has one.” Steven’s other role is public education.
The Nine Springs biomonitoring program is in a long-term mode. No changes are anticipated unless regulations require them. Previous data clearly show how changes in the plant’s treatment process have produced a positive effect on fish, aquatic insects and water quality.
