Lake Ontario shows improvements in Lake Trout and Lake Sturgeon populations, but nuisance algae like Cladophora is distributed across broad regions of the lake’s nearshore zones.
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Be a source of safe, high quality drinking water.
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Allow for unrestricted swimming and other recreational use
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Allow for unrestricted human consumption of the fish and wildlife
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Be free from pollutants that could harm people, wildlife, or organisms
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Support healthy and productive habitats to sustain our native species
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Be free from nutrients that promote unsightly or toxic blooms
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Be free from aquatic and terrestrial invasive species
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Be free from the harmful impacts of contaminated groundwater
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Be free from other substances, materials or conditions that may negatively affect the Great Lakes
Lake Ontario continues to be a good source for producing high-quality drinking water. Toxic chemicals in Lake Ontario are assessed as Fair and long-term trends indicate that concentrations are declining in many monitored media. Lake Ontario fish continue to be a nutritious food source. While consumption advisories for certain species of fish remain in effect, some advisories have recently become less restrictive.
Lake Ontario beaches and nearshore waters provide good opportunities for swimming and other recreational uses. Excessive growth of Cladophora in localized nearshore areas, due in part to nutrient loading and increased water clarity caused by the filtering effects of invasive Dreissenid Mussels, can degrade habitats and foul beaches. The status of algal bloom extent in Lake Ontario is Good with an Unchanging trend, although there are localized blooms in some embayments. Nutrient concentrations are considered to be Fair as offshore phosphorus concentrations remain below established objectives.
Coastal wetland amphibian and birds are in Fair condition. However, shoreline development and invasive species like Phragmites are ongoing stressors for coastal wetland health. Habitat connectivity between the tributaries and the lake is Fair and the trend is Improving. Lake Trout populations are Improving, due in part to successful Sea Lamprey control. Prey fish communities are dominated by non-native species and are in Poor condition; but some native prey fish, such as Deepwater Sculpin, are recovering naturally and restoration efforts for populations of other native prey fish are proving successful. Lake Sturgeon populations are showing some signs of recovery with stocking programs leading to successful spawning in tributaries, including the Genessee River. Zooplankton and Phytoplankton communities are assessed as Fair and Good, respectively. However, Diporeia, an important food source for prey fish, is now rarely found during regular sampling. Invasive species, including Sea Lamprey, Zebra and Quagga mussels and Phragmites, have significantly altered the Lake Ontario food web and habitat for native species.
Groundwater quality is assessed as Fair based on chloride and nitrate concentrations. Over the past 50 years, the population in the Lake Ontario basin has grown by more than 60%, with rapid urban expansion particularly evident in the western Canadian portion of the basin. This ongoing growth is placing increasing pressure on local watersheds and nearshore ecosystems. Long-term increases in surface water temperatures and decreasing winter ice cover are occurring.