One reason the Androscoggin River does not meet Class C water-quality standards is because of sewage overflow from Lewiston and Auburn.

The overflow happens after big rainstorms. Rain from parking lots, roofs and streets flows into the sewer drains, mixing with sewage. The extra water overwhelms the system, prompting sewage to bypass the treatment plan and flow into the river.

According to the Maine Department of Environmental Protection, the cities are spending a lot of money to correct the problem, essentially buttoning up the collection system to keep sewage out of the river.

“Auburn’s almost done; Lewiston has some work to do,” said Andrew Fisk, director of the DEP’s Bureau of Land and Water Quality.

According to DEP data, storm overflow events in Lewiston-Auburn often numbered 80 per year in the 1980s and 1990s. The number ranged from 23 to 41 in the past nine years.

The volume of sewage going into the river has also gone down, Fisk said. Statewide, some 6 billion gallons of sewage overflow was discharged into Maine water in 1990, compared to 2 billion in 2009, which was a heavy rain year.

Lewiston, Auburn and the Lewiston-Auburn Water Pollution Control Authority are in the 11th year of a 15-year compliance plan with DEP, said John Storer of the Auburn Water and Sewerage districts.

Auburn is building a dedicated drain system for storm water, since Auburn has a smaller problem than Lewiston, Storer said.

Initially, Auburn had 11 locations along the Little Androscoggin and Androscoggin rivers where sewage could overflow during storms. Lewiston had 31, according to Lewiston Public Works.

So far, Auburn has eliminated eight of the 11, and plans to eliminate two more this year. Auburn has spent $8 million in the five years. Lewiston is about two-thirds of way addressing the runoff, said Public Works Director David Jones, In the past five years, Lewiston has invested more than $10 million, another $10 million is expected to be spent in the next five years, Jones said. That will bring “tremendous improvement,” he said.

By 2014, the cities have to eliminate overflows, “or prove to us they’ve done everything practical” to minimize them, Fisk said.

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