Chlorophyll-a Nuisance Level Frequencies
  
Percent of Samples During Growing Season Exceeding Various Nuisance-Level (or "Bloom") Criteria, calculated from Observed or Predicted Mean Chlorophyll-a, Assuming a Temporal CV of .62 and a Log-Normal Frequency Distribution:
  
  FREQ(CHL-a > 10 mg/m3) %        "Scums Evident"
  FREQ(CHL-a > 20 mg/m3) %        "Nuisance Conditions"
  FREQ(CHL-a > 30 mg/m3) %        "Severe Nuisance Conditions"
  FREQ(CHL-a > 40->60 mg/m3) %  "Even Worse"
  
Ref: Walker, W., "Statistical Bases for Mean Chlorophyll-a Criteria"  Lake and Reservoir Management: Practical Applications, North American Lake Management Society, Proceedings of Fourth Annual Conference, McAcfee, New Jersey, October 1984.