Clean Water

The diverse ecosystems, working
landscapes, and vibrant communities
that inspire and sustain us depend on
clean water. Learn about pollution
reduction strategies.

Healthy Habitats
Connect Us All

Lakeshores, stream banks, and wetlands are critical to clean
water and biodiversity. Learn about efforts to improve
habitat connectivity in the Basin ecosystem.

We Care for
What We Know

Recreation fosters stewardship of the Basin’s rich
natural and cultural heritage by connecting people
to the landscape while supporting local economies.
Learn about ways to explore the Basin.

Informed Citizens
Make Wiser Choices

Citizens who have an understanding and
appreciation of water resources make informed
choices about actions that might contribute to
pollution. Learn about education programs.

    Water & Environment

    Did You Know?

    There are more than 30 marinas on Lake Champlain and more than 90 fishing-related businesses within ten miles of the Lake.
    Find out more


    Nutrient Pollution

    Algae bloom in Missisquoi Bay

    Scientists collect water samples from an area of Missisquoi Bay with algal blooms. Photo: Québec MDDELCC

    Nutrients are as critical to a lake ecosystem as they are to terrestrial ecosystems. Aquatic plants and algae require nitrogen, phosphorus, and a suite of micronutrients. When there is too much of a particular nutrient, certain plants or algae can dominate a system. Phosphorus is one of the primary water quality challenges in Lake Champlain. Found in lawn fertilizers, manure, as well as in human and other animal waste, phosphorus causes algal blooms and excessive aquatic plant growth when present in high concentrations. These plants and the water quality problems that occur when they decompose can harm fish and other organisms and limit the use and enjoyment of the Lake.

    Phosphorus levels are above established targets in several parts of Lake Champlain, including Missisquoi Bay, St. Albans Bay, and the South Lake, where algal conditions are a nuisance for much of the year. Cyanobacteria (blue-green algae) often pose public health threats during the summer in Missisquoi Bay and other northern parts of the Lake. In an effort to address the problem, Vermont and Québec signed an agreement for reducing phosphorus to Missisquoi Bay that lays out a collaborative approach to the issue.

    Phosphorus Sources

    As a result of targeted efforts and infrastructure improvements in the last 20 years, less than 10% of the phosphorus in the Lake now comes from point sources, such as wastewater treatment facilities and industrial discharges. Runoff from roads and developed areas, and from lawns, farmlands, and other rural areas (called nonpoint sources) contribute more than 90% of the phosphorus. It is also likely that some phosphorus cycles up into the water from the sediments in the lake bottom, although we don’t yet know how much this in-lake cycling contributes to the overall amount of phosphorus in the lake.

    A 2007 study conducted for the Lake Champlain Basin Program estimated that 46% of the nonpoint source phosphorus load is from urban land uses and about 38% is from agricultural land (using 2001 satellite imagery and the loading method of analysis). Urban land included all roads, cities, suburbs, lawns, and large-lot buildings. More recently, an LBCP-funded project examining phosphorus sources in the Missisquoi River Basin estimated that about 39% of the phosphorus delivered to the lake is from agricultural use.

    Phosphorus Reduction Progress

    P loads by Lake segment

    Lake Champlain phosphorus concentration by lake segment, 1990-2017

    The phosphorus reduction strategy for Lake Champlain has begun to show promising results. Data gathered between 1990 and 2011 show no significant positive or negative trends in most segments of the Lake (except for Mallet’s Bay, St. Albans Bay, the Northeast Arm, and Port Henry, which are deteriorating). Most segments either consistently meet or exceed the phosphorus targets for that particular lake segment. The most substantial gains in phosphorus pollution reduction have been achieved by targeting point sources, mainly through wastewater treatment plant upgrades.


    Phosphorus load from wastewater treatment facilities, 1990-2016


    Figure: nonpoint source phoshporus loads graphic

    Phosphorus loads to Lake for nonpoint sources and wastewater treatment facilities. Source: 2012 State of the Lake Report

    However, nonpoint source loads still significantly exceed targets in at least four of the five major lake segments. With the exception of Shelburne Bay and a portion of the New York share of the South Lake watershed (South Lake A), all smaller watershed segments exceeded target levels. Conversion of agricultural and forest land to developed land, inadequate implementation of Best Management Practices (BMPs), and streambank erosion continue to slow progress in this area.

    More about phosphorus

    For the most recent information about phosphorus, please visit the “Phosphorus” page of our State of the Lake website

    To learn about actions taken to address nonpoint phosphorus pollution, please visit the “Clean Water Goal” in The Lake Champlain Management Plan Opportunities for Action.

    For additional maps and information, please visit the Lake Champlain Basin Atlas.

    Nonpoint Source Pollution Fact Sheet

    What is the State of the Lake?

    What is the
    State of the Lake?

    Learn about the health of Lake Champlain in the 2018 State of the Lake report. Read about trends in key indicators of water quality and ecosystem health. Read the State of the Lake report


    Make Some Waves

    From using lake-friendly cleaning products to volunteering with a local watershed group, you can help restore and protect the Lake Champlain Basin. Find out how you can get involved

    Track Our Progress

    Track Our Progress

    Explore the goals and actions of our partners and track our progress online with the Opportunities for Action website. View Opportunities for Action

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    Lake Champlain Basin Program

    Lake Champlain Basin Program
    54 West Shore Road
    Grand Isle, VT 05458
    800-468-5227 (NY & VT)
    or 802-372-3213