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About HBPA
What is the Hop Brook Watershed?


Hager PondThe Hop Brook Watershed includes Hager Pond in Marlboro, Grist Mill Pond and Carding Mill Pond in the Wayside Inn Historic District, Stearns Mill Pond and the connecting streams & ponds. Hop Brook flows 9.4 miles through Sudbury and is the largest tributary of the Sudbury River.

Hager Pond
What is the Hop Brook Protection Association?
The HBPA is an incorporated nonprofit organization formed by concerned citizens who donate time, energy & ideas. Its goal is to stop the excessive nutrient discharge into Hop Brook by the Marlboro Easterly Wastewater Treatment Plant, restore the Hop Brook System to Class B water standards and protect the ponds, streams & wildlife from further pollution.
What is the problem?
Carding Mill PondExcessive nutrients in the water, especially phosphorous, have caused algal & aquatic weed growth that makes these ponds & streams inhospitable to humans, fish & waterfowl. During the hot summer months the algae in the slow moving water becomes putrid as it decays, impeding the use of the Hop Brook ponds for fishing, swimming or canoeing.


                     Carding Mill Pond
Who is responsible?
In 1989 a study of the Hop Brook Watershed by Whitman & Howard, Inc. found that the main source of excessive nutrients is the Marlboro Easterly Wastewater Treatment Plant. Over 6,000 petitioners requested that the U.S. Environmental Protection Agency restore the water quality of the Hop Brook Watershed by requiring that the Marlboro Sewage Facility decrease the phosphorous level of its effluent discharged into the ponds. The Marlboro Easterly Wastewater Treatment Plant has been operating under a 1988 National Pollution Discharge Elimination Systen (NPDES) permit which was due to be renewed in October 1993. HBPA  has demanded that the next  NPDES permit issued to the Marlboro Easterly Wastewater Treatment Plant must require a stricter phosphorus limit. The EPA issued a new NPDES permit specifying reduced nutrient limits in October 2006.