More from MPR
July 12, 2005
Moorhead, Minn. — Just after noon on a calm, partly cloudy day, Dick Barbari backs his boat away from the dock at his Cotton Lake home.
"Another perfect day in paradise," Barbari says with a grin.
Barbari and his Cotton Lake neighbor, John Peterka, will spend the next hour or so collecting water quality data.
Cotton Lake is a fairly typical mid-sized Minnesota lake. Its shoreline is filled with cabins and homes and a small resort.
Dick Barbari watches his depth finder and checks landmarks on shore to find the spot where he regularly checks water clarity. He stops the boat in 27 feet of water.
While Peterka drops anchor, Barbari pulls out a white metal disk about the size of a small frisbee, attached to a rope, which is marked every six inches. The Secchi disk is the basic tool of water quality monitors.
Barbari leans over the edge of the boat and watches the white disk sink until it disappears in the blue green water. He pulls it back up, counting the marks on the rope. The Secchi reading is 12.5 feet.
These readings are taken once a week from June through September. John Peterka says the water is very clear in the spring, but in July and August algae blooms reduce visibility before cool fall temperatures clear the water again.
"So what we're looking at is a seasonal average from June to September. There is kind of a seasonal bump and decline," says Peterka. "And really the only time algae is a problem, and people do complain about algae blooms is late summer when these blue green algae form scum on the water and the wind blows it to shore and people are seeing a kind of pea soup."
Algae is one indicator of the health of a lake. Too many nutrients in the lake bring a bigger crop of algae and weeds. Those nutrients can come from runoff from farm fields or lakeshore lawns.
Using algae as an indicator, Cotton Lake is relatively healthy. The Secchi disk readings have been consistent for a decade or more. Peterka says what they're measuring is "swimability" or recreational quality of the lake.
Water clarity is only one small component of water quality. There's no monitoring for pollutants like bacteria from runoff or failing septic systems and no measurement to track the impact of livestock or wildlife feces on the water quality of Cotton Lake.
After the Secchi disk data is written down, John Peterka lifts a long white plastic pipe from the floor of the boat.
"What we're doing is collecting a sample of water with this tube which is 2 meters or 6.6-feet long to represent a column of water in the lake instead of just taking it from the surface which might be affected by algae scums," says Peterka.
The water collected in the tube is poured into two containers which are then put in a small cooler. The samples are taken to a lab in Detroit Lakes where the water will be tested for phosphorus and chlorophyl levels, also indicators of algae growth in the lake. This test is done every three to five years.
John Peterka would like to see more lake monitoring. He thinks there should be a system for monitoring the spread of invasive species.
The Minnesota Pollution Control Agency is responsible for monitoring Minnesota lakes, and the agency relies on volunteers like Dick Barbari and John Peterka to collect the data.
The volunteer network is the most comprehensive part of a patchwork of water quality monitoring across the state. While volunteers monitor nearly 1,000 lakes, many thousands of other lakes are not regularly monitored.
John Peterka and Dick Barbari say they volunteer because they want make sure Cotton lake stays healthy.
Dick Barbari is optimistic as he steers the boat back toward his dock.
"We're much more conscious now of taking care of (the lake) so the sins of the past are here and I don't think there are as many sins going on now. The people raking leaves into the lake and dumping sewage into the lake is less than it used to be. But I think the biggest factor yet is education," says Barbari.
Barbari says too many people still don't understand the role they play in keeping Minnesota lakes healthy by keeping pollutants out of the water.