Nitrogen is important to all living things. Nutrients such as nitrogen occur naturally in both freshwater and saltwater. Plants and animals need nutrients to grow and survive. Too much nitrogen in the water fuels the growth of excess algae, creating dense blooms that block sunlight and reduce oxygen for fish and other organisms. Nitrate and nitrite together are of interest because they are the form of nitrogen most available to algae.
How is it scored?
Nitrate + Nitrite (NN) was used as an indicator in both the watershed and lake analysis. Year-round data for 2018 were analyzed. For each NN sample, the measurement was compared to the threshold on a pass/fail basis. Site scores were averaged into an overall region nitrate+nitrite score.
The nitrate-nitrite threshold used for the western Lake Erie basin analysis was 0.1 mg/L from Chaffin et al. 2014.
The nitrate-nitrite threshold used for the western Lake Erie watershed analysis was the Ohio EPA warm water habitat threshold 1.5 mg/L.