Nutrient Loading and Impacts in Lake Champlain – Missisquoi Bay and Lake Memphremagog Missisquoi Bay. IJC Collection Lake Memphremagog. IJC Collection Missisquoi Bay Cyanobacteria. Pierre Leduc Prepared by the International Joint Commission April 21, 2020 Table of Contents I. Synthesis Document ........................................................................................................................ 3 A. Context ........................................................................................................................................ 3 Cyanobacteria .................................................................................................................................. 3 Actions and Consequences of Non-action ........................................................................................ 3 The Governments’ Reference ........................................................................................................... 4 IJC’s Approach to the Reference ...................................................................................................... 5 Workshops to Review Science and Policy on Nutrient Loading ........................................................ 6 Public Meeting and Online Consultation .......................................................................................... 6 B. IJC Analysis of SAG Reports ....................................................................................................... 7 C. Common Basin Recommendations and IJC Recommendations ..................................................... 9 SAG Recommendations ................................................................................................................. 10 IJC Recommendations ................................................................................................................... 10 D. Concluding Remarks .................................................................................................................. 12 II. Champlain ......................................................................................................................................... III. Memphremagog ................................................................................................................................. IV. Global scan ........................................................................................................................................ Synthesis Document Authors: Michael Laitta, Mark Gabriel, Adam Greeley, Robert Phillips, Michele D’amours, Pierre-Yves Caux. Synthesis Document Reviewers: Victor Serveiss, Catherine Lee-Johnson Acronyms BMP - Beneficial Management Practices CSA -Critical Source Areas HAB - Harmful Algal Bloom IJC –International Joint Commission LCBP –Lake Champlain Basin Program MOU - -Memorandum of Understanding NAS - Nutrient Accounting System RAP - Required Agricultural Practice REA - Regulation on Exploitation of Agriculture SAG - Study Advisory Groups SPARROW - SPAtially Referenced Regression on Watershed attributes TMDL – Total Maximum Daily Load Acknowledgements: The IJC would like to thank several groups that helped make this binational study possible including the Lake Champlain and Memphremagog Study Advisory Groups, participating federal, provincial and state, and municipal agencies, academic institutions, and basin and lake organizations. Both reports benefitted greatly from public participation and input provided at public meetings, workshops, and public consultations. The contributors also thank the Canadian and United States governments’ extension following the winter 2018/2019 U.S. government shutdown to allow adequate time to finalize the report. 2 I. Synthesis Document A. Context Public concern for blue-green or harmful algal blooms (HABs) has continued to intensify over the past decade within the entire Champlain / Memphremagog region. Summer season HABs, including cyanobacterial blooms and associated microcystin toxins, have resulted in socioeconomic losses (see Sections II and III) and have raised concerns about public health, recreation, and safety of drinking water. These effects and losses are anticipated to persist in the future, from continued anthropogenic impacts and will be exacerbated by climate change and extreme weather. Cyanobacteria Algal blooms can occur in water bodies with excess nutrient inputs as part of the natural eutrophication process but may be exacerbated by inputs from anthropogenic sources. While most algal blooms are benign, some can be toxic to humans and wildlife. For example, the cyanobacteria Microcystis can produce both neurotoxins and hepatotoxins. Exposure is through ingestion by drinking contaminated water or by consuming fish or other biota that have accumulated the toxin. In Lake Champlain and especially in Missisquoi Bay (see Section II for description) 400 years of settlement has impaired aquatic life and major water uses including recreational and potable waters. Drastic and sustained measures over the long-term are now needed to remedy the situation. Due to the Bay’s shallow depth and restricted flow dynamics, discernable improvements will not be observed for decades to come. In contrast, Lake Memphremagog is relatively pristine (see Section III for description). Although some eutrophication and cyanobacteria occur naturally in the lake (e.g., Fitch Bay) anthropogenic input at its southern end have caused periodic water impairments such as beach closures. Because of the differences between Missisquoi Bay and neighbouring Lake Memphremagog governments should consider unique approaches in each basin to address their water quality issues. The former basin requires intense remediation; the latter requires protection. Actions and Consequences of Non-action Public concern about water quality in Lakes Champlain and Memphremagog is growing in both Canada and the United States. The focus is on the impacts of elevated phosphorus levels causing the proliferation of algal blooms which have adversely affected recreation, human health, and ecosystems on both sides of the border. HABs in Missisquoi Bay (the Bay) have been a concern since the 1950s. The Lake Champlain Basin Program’s (LCBP), 2015 State of the Lake Report, noted that excess phosphorus is a concern in most segments of the lake, these being highest in the Bay and that algal blooms will continue to develop until concentrations are reduced. Governments, lake organizations and academia have invested and studied the problem for decades and all recommended the need for major reduction in phosphorus inputs to the Bay. Studies of the Bay, conducted by the International Joint Commission (IJC) in response to References from the governments of Canada and the United States in 2004 and 2008, identified 3 the Bay’s specific conditions and constant excessive nutrient loading as the cause of HABs. In an attempt to increase the flow of water out of the Bay, the Swanton Bridge was built, and part of the causeway removed. Although government actions throughout the basin are occurring, the trend is towards concerted site-specific efforts that integrate all aspects of the problem (e.g., hydrological, socioeconomic, regulatory; see Global Review, Section IV). Should the status quo prevail, the bay will continue its path of accelerated eutrophication. Although similar concerns surrounding water quality are evident in Lake Memphremagog basin, the extent of the problem is small in comparison to Missisquoi Bay. The problem is not going unnoticed however and basin and lake organizations have established surveillance plans and actions plans according to their means. Governments have a presence in Lake Memphremagog and are investing in it in a manner that is in proportion to the scale of all basins under their responsibility. With only about 15% of land used for agriculture in the basin and most of the rest Cyanobacteria city of Magog. IJC Collection forested, even an occasional HAB should send a strong signal to governments that site-specific attention at the watershed-level is required rather than reliance upon jurisdiction-wide policies and investments. The Governments’ Reference In the October 19, 2017 letter of Reference, Governments asked the IJC to solicit recommendations on how to address nutrient loading in both Lake Champlain-Missisquoi Bay and Lake Memphremagog. Specific to the former, the IJC was asked to gather and review information from federal, provincial, state, and municipal agencies, academic institutions, and other entities in the region on existing monitoring programs and measures being taken to address water quality concerns. Based on the information collected, the IJC was to provide Governments with recommendations on how current efforts and programs can be strengthened. The Governments asked that the recommendations include a summary of gaps or opportunities and that the recommendations identify possible approaches to strengthen collaboration, efficiency, or impact. Specific to the latter, Governments asked IJC to collaborate with relevant government agencies, academic institutions and other entities in the region to identify the range of nutrient loading issues that are of concern in the Basin and to make recommendations on how current efforts can be strengthened. For that basin, the recommendations should also include the consideration of management approaches currently applied in Lake Champlain and Missisquoi Bay, and the effectiveness of those approaches in combatting HABs. The IJC has