Though progress has been made to restore and protect the ecological condition of the Great Lakes, the impacts of excess nutrients and invasive species continue to affect the region, according to a new 2017 State of the Great Lakes Highlights report from Environment and Climate Change Canada (ECCC) and the US Environmental Protection Agency (EPA).
The report assesses how the Great Lakes are doing using nine indicators based on objectives of the 2012 Great Lakes Water Quality Agreement: drinking water, beaches, fish consumption, toxic chemicals, habitats and species, nutrients and algae, invasive species, groundwater quality, and watershed impacts and climate trends. Scientists and other experts interpret the data to determine if these indicators are in good, fair or poor shape, and if they’re improving, deteriorating or are largely unchanging. A technical report on how each conclusion was reached will be released at a later date, according to EPA and ECCC.
On the positive side, the report indicates that the quality of drinking water from the Great Lakes is good, and is staying that way, as long as it’s treated. That water is tested on microbial, radiological and chemical parameters to determine if it’s safe; the data used was from 2012-2014. Ontario and the eight Great Lakes states all use different methods to determine water quality, but the overall conclusion is that water quality standards were met for the vast majority of the applicable population.
Beach conditions range from good to fair in the 2011-2014 reporting period, depending on location, though they were found to be in poor shape and deteriorating (compared to the 2008-2010 period) along Lake Erie beaches in both countries. This is due in part to E. coli fecal bacteria, which can make its way to the waterfront from wastewater treatment plants, storm runoff, malfunctioning septic systems and large flocks of birds.
For toxic chemicals, the lakes are in fair shape with localized areas of contaminated sediment, and trends suggest the lakes are either improving or unchanged over 40 years of monitoring.
On the flip side, invasive species are continuing to have a negative impact, with an overall “poor and deteriorating” trend. While only one new non-native aquatic species has been found since 2006 – a type of zooplankton – invasives already in the lakes have continued to cause problems where they’ve been established. Sea lampreys continue to prey on native fish despite the recent success of control measures.
Zebra and quagga mussels continue to dominate the bottom-dwelling ecosystem and impact plankton communities throughout the lakes. Five terrestrial invasive species - Phragmites, emerald ash borer , purple loosestrife, garlic mustard and Asian long-horned beetle - were collectively found to be widely distributed and expanding their ranges. They are a significant factor in the negative assessment of invasive species since they can degrade water quality and habitat.
Phosphorus, nutrients and algal blooms are considered “fair” in the Great Lakes overall, but conditions are either unchanging or deteriorating, depending on the lake. Nutrient concentrations are worsening in all lakes but Superior, and the green algae Cladophora – which can cause beach fouling and clog water intakes – is prevalent in Lakes Michigan, Erie and Ontario. Harmful algal blooms are poor and worsening on Lake Erie, and fair and worsening on Lake Ontario.
Other indicators used for the report are overall fair and unchanging. On fish consumption, all lakes are considered fair – with polychlorinated biphenyls (PCB) and mercury concentrations declining in Lakes Superior, Michigan and Ontario but either stable or slightly increasing in Erie and Huron.
Habitat conditions and the health of specific species populations are variable across the basin, being good in some areas and in bad shape elsewhere. Wetlands are being restored in some areas but suffering from nutrient runoff and sedimentation elsewhere. Despite setbacks from invasive frog-bit and water chestnut plants, there have been improvements to wetland fish species diversity across the board. The state of the aquatic food web is a mixed bag; mussels are causing phytoplankton conditions to deteriorate in Lakes Michigan, Huron and Erie, and the small shrimp-like Diporeia species has suffered in those lakes and Ontario - possibly because of mussels. Lake sturgeon populations are poor but improving, and other major fish species are either fair or good, but largely unchanging.
On watershed impacts and climate trends, some lakes are faring better than others. Erie is in poor shape on three sub-indicators – forest cover, land cover and watershed stressors – while Ontario is in poor shape on watershed stressors and hardened shoreline development. Development can exacerbate nutrient runoff problems and other pollutants. Climate trends suggest more precipitation, less winter ice cover and increases in summer water temperatures may continue. These in turn could impact the amount of habitat available for species, allow invasive species to push further north into historically cooler areas, and lead to extended growing seasons – and thus potentially more increases in runoff.
A State of the Great Lakes 2017 Technical Report will be released soon, according to ECCC and EPA. Previous State of the Great Lakes reports can be found on the US Environmental Protection Agency and Government of Canada Publications websites.