Early Monday morning, the St. Albans City sewage system dumped more than a quarter-million gallons of sewage and storm runoff into Stevens Brook, which flows into St. Albans Bay.
The release was authorized under state regulation because St. Albans uses a combined sewer system, which treats both stormwater and rainwater. The design allows street runoff to be cleaned before it flows back into the water system, but it also leads to releases of sewage and stormwater when water is flowing into the system faster than the system can treat it. As a result, regulators in Vermont allow combined sewer operators to release overflows during wet weather to prevent backups into homes and businesses or problems within treatment plants themselves.
The St. Albans City overflow of an estimated 333,600 gallons was one of the three largest dumps this year. The other two were both in the city of Vergennes and totaled more than a million gallons. Last year by June 23, a total of 42,622 gallons of untreated water had flowed into state waters through combined sewer overflows.
St. Albans Bay has been one of the main trouble spots for toxic blue-green algae blooms caused by an excess of phosphorus. The blooms in 2014 lasted weeks, and were part of the impetus for the state’s action this year to combat water pollution. The state is also working to satisfy requirements from the Environmental Protection Agency limiting phosphorus pollution into Lake Champlain under the Clean Water Act.
The St. Albans City sewer system also treats waste- and stormwater from some parts of St. Albans Town, but the town selectboard is considering the construction of a wastewater plant for just the town.
According to EPA estimates, wastewater treatment plants make up 3.1 percent of Vermont's phosphorus contribution to Lake Champlain.