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The Casco Bay Nutrient Council, a group with wide representation including local and state government, wastewater treatment and stormwater management professionals, researchers, community development organizations, and water quality advocacy organizations, was convened in 2017 to develop recommendations to policymakers, regulators, and funders on how best to assess, understand, convey and reduce the negative impacts of nutrients on Casco Bay.

While in common usage “nutrients” are things that make food nutritious or healthy, nutrients in Casco Bay refers to nitrogen, phosphorus, and silica. These chemical elements boost plant growth in aquatic ecosystems and such effects can lead to negative impact on water quality. Available information suggests that most of the time nitrogen is the nutrient of primary concern in the Bay.

Concentration of nitrogen in the Bay is at a level of concern, even though Casco Bay is still relatively healthy compared to many similar bays on the East Coast. The Bay is experiencing preliminary ecological effects of excess nutrients, including algae blooms, damage to eelgrass beds, and coastal acidification. Population growth and climate change effects like warming waters and altered precipitation are likely to make the problem more severe in future. This combination heightens concern about Casco Bay’s long term ability to provide habitat for commercially fished/farmed species and to provide a clean, healthy environment for recreation and tourism.


The work of the Nutrient Council has been funded by the U.S. Environmental Protection Agency under Cooperative Agreements #CE96190301, #CE00A00063 and #CE00A00299 with the University of Southern Maine, Casco Bay Estuary Partnership.


Casco Bay, Casco Bay watershed



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