The Online Lower Minnesota River Watershed District News, December 2004
  Firemen's Brickyard Courthouse
data year 2003 2003 2003
total phosophorus 25.5 18.7 19.4
chlorophyll 3.3 2.4 3.8
water clarity 3.1 3.9 3.9
grade  a- a a
 

Clayhole Lake Water Quality Grades

Table 3 from the Bonestroo report.

Phosphorus affects the algae growth in a lake; chlorophyll here signifies algae growth.

Top quality, or A, ratings for any lakes would be:
< 23 phosphorus
< 10 chlorophyll
> 3.0 clarity