United States, Canada Agree on Lake Ontario Phosphorus Limits

The United States Environmental Protection Agency (EPA) and Environment and Climate Change Canada have completed their review of the phosphorus limits for Lake Ontario, per their responsibilities under the Great Lakes Clean Water Agreement of 1972. Their decision, in line with the recommendation made last year by a team of scientific experts and reviewed by the public, is to keep the limits at the current level, 10 micrograms per liter of open water concentration and 7,000 metric tons per year of loading.

High phosphorus levels cause harmful algal blooms (HABs), which are detrimental to environmental and human health and inhibit recreational activities and water quality. Since the 1980s, Lake Ontario has consistently been under the limit for phosphorus open water concentration. The 2022 State of the Great Lakes report, released every 5 years by the EPA and ECCC, scored Lake Ontario’s nutrient indicator as “Fair and Unchanging,” with “Fair” the middle ground between “Good” and “Poor.” The report gave a rosier assessment of “Good and Unchanging” on the harmful algal bloom indicator, however.

For more information on nutrient reduction and harmful algal blooms, watch NEMWI's webinar here.



Reported by Alex Eastman, NEMWI Staff

USGCRP Hosts National Climate Assessment

Midwest Region Webinar

The U.S. Global Change Research Program hosted the twenty-third installment of its National Climate Assessment (NCA5) webinar series last Tuesday. Attendees heard from Midwest Region Chapter Lead Aaron Wilson as he discussed the central findings and future considerations for building Midwestern climate resilience. While Wilson contested the notion that the region will serve as a “climate refuge,” he emphasized that “Midwesterners are responding in ways that offer hope for the future as we think about mitigation and adaptation to climate change.”

The midwestern U.S. will be subject to rapidly evolving climatic conditions over the coming half-century, according to Wilson. He explained that average annual temperatures already have risen 0.5-2℉ above pre-industrial levels, and the region can expect to experience additional increases of 3-4℉ by 2053. A significant amount of this warming will be concentrated in the Upper Midwest and areas surrounding the Great Lakes. Wilson noted that the Midwest also will become much wetter in the coming decades. He stated that “across the board, anyway we look at precipitation changes, [metrics] all trend upwards.” These developments suggest that the region will become hotter and wetter, but Wilson emphasized that the oscillations between hot/cold and wet/dry conditions are becoming more extreme and constitute cause for concern.

Adaptation and mitigation were central themes during the webinar, and all five chapter key messages are oriented around one or both strategies. From climate-smart agricultural practices to erosion reduction to weatherization programs, the Midwest has a litany of adaptation and mitigation measures at its disposal. Successful implementation will depend upon consistent stakeholder engagement (with a particular focus on indigenous and marginalized communities) and adherence to proven methods. One such successful program highlighted during the webinar was the “Healthy Ports Future Initiative,” a dynamic, multi-agency sediment management approach that “restored [and] built wetland resilience” in the Great Lakes states.

Although a majority of the findings published in the chapter are characterized as “likely, high confidence,” the impact of climate change on Great Lakes ecosystems remains poorly understood. Wilson concluded the webinar with a plea for more research, noting “Better representation of the Great Lakes region within our models would enhance confidence [in our projections].”

NEMWI will continue to track this webinar series and monitor the USGCRP website for the release of the full NCA5 report. The Midwest Region Chapter is available for download here, and you can find a recording of the webinar on the USGCRP YouTube channel, accessible here.

Reported by Ethan Groboski, NEMWI Intern, Brown University

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