Parameter

Action

Threshold Level

Units

Description

Total algae cell

density

100,000

Cells・mL−1

Algae dispersed in the water column, independent of classification

Blue-green

algae cell density

10,000

Cells・mL−1

Cyanobacteria cells only, even if the above overall algae density is not met

Green algae mat

coverage

5%

Surface or benthic area pond

coverage

18.6 sq m (~200 sq feet) visible area covered with green algae (or other non-blue green algae types)

Blue-green algae mat coverage

2.5%

Surface or

benthic area pond

coverage

9.3 sq m (~100 sq feet) coverage with cyanobacteria as dominant biomass of mat

Blue-green algae scum coverage

2.5%

Surface area

pond coverage

9.3 sq m (~100 sq feet) coverage with cyanobacteria as dominant component of accumulated surface scum

Chlorophyll α

concentration

20

µg・L−1

Measured in homogenized planktonic water sample

Secchi Depth

45.7

cm

3 point average