2017 NATIONAL LAKES ASSESSMENT

Nutrient Pollution

46%

Elevated
Nitrogen

45%

Elevated
Phosphorus

Nutrient pollution was the most
widespread stressor measured

Biological Condition

Good,
43%

Fair,
29%

Poor,
24%

Biological condition based on
macroinvertebrate communities

Poor 45 % Good 34% Fair 20%

Chlorophyll a, indicates the amount of
algae and cyanobacteria present and
was in excess in 45% of lakes

Chemical Indicators

The herbicide atrazine was detected in
30% of lakes and exceeded the EPA
"concentration level of concern" in
0.5% of lakes

•I

Microcystins were detected in 21% of
lakes and levels exceeded the EPA
recreational criterion in 2% of lakes

https://www.epa.gov/national-aquatic-resource-survevs/nla

oEPA

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