Herald JournalHerald Journal, Dec. 22, 2003

Area lakes are neither dirty nor clean, study says

By Paul Maravelas

Area lakes are neither heavily polluted nor very clean, concluded a three-year study done by the Wright Soil and Water Conservation District.

The lake monitoring, done by district staff and lake volunteers, addressed water quality at 29 Wright County lakes.

A lake's general health may be determined by several factors that can be summed up by one number called a Trophic State Index (TSI).

The TSI is an index based on the relationships between total phosphorus, chlorophyll-a, and Secchi disk readings, the latter of which are based on visual water clarity.

The index ranges from 0 to 100, from oligotrophic (clear, nutrient-poor lakes) to hyper-eutrophic (green, nutrient-laden lakes).

As the numbers increase, it indicates more eutrophic conditions for that particular lake, Wozney said.

Area lakes were generally rated from about 50 to 75. When lakes are pure enough to be rated less than 30, their water is clear and oxygenated throughout the year.

When rated more than 70, the lake experiences heavy algae blooms in summer. When rated more than 80, the lake suffers from scums, summer fish kills, and a dominance of rough fish.

The results are still preliminary, according to Brad Wozney, a water resource specialist with the district.

Data from five years should be analyzed to accurately evaluate trends, and the lake monitoring began in 2001, he said.

Some data exists for a few area lakes as far back as 1981, but it wasn't always comparable, Wozney said, and wasn't used in the study.

Area lakes generally have high TSI scores, but the scores were not "out of the ordinary for what was found in 2001," and didn't reveal any severe trends, according to Wozney."

"There are some polluted lakes, some that need help," he said, but staff and money is limited. And the district wrestles with the dilemma of devoting its resources to the best causes.

"Do you protect those with good water quality, or try to improve those that are the worst?" Wozney pondered.

The Wright Soil and Water Conservation District provides technical and financial assistance for feedlot improvements and erosion control.

The district is governed by five elected officials, and has a staff of five. Their work is aided by volunteers from local lake associations.

"There are a number of lake associations with excellent leadership, doing work that we aren't able to, including data collection, and making land-use decisions." Wozney called the volunteers "an extension of our office," with whom he maintains communication via news releases and e-mail.

The district also distributes information related to lake issues to area residents.

"Land use is ultimately going to affect water quality" Wozney said.

Area lakes are affected by agriculture and housing, and "each is part of the problem, and each can be part of solution."

Among the problems for lakes are decreasing wetlands, agricultural runoff and erosion, the agitation of the shore and bottom from powerboats, and pollutants from lawn fertilizer and defective septic tanks.

"We shouldn't be discouraged if there aren't immediate results," Wozney said. "It took many years to get to this point with our lakes, and it will take many years to restore them."

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