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Bass Lake Chlorophyll-a Chlorophyll-a is the pigment in plants and algae that makes them green. Chlorophyll-a is a measurement of algal concentration in the water. more information on Chlorophyll-a Bass Lake chlorophyll-a at site 201 has been monitored from 2003 to 2011, and has an average of 5.6 ppb. This algae concentration is similar to Big Pelican Lake (5.2 ppb) and higher than Fish Lake (4.3 ppb). 2011 Results In 2011, the chlorophyll-a concentration in Bass Lake averaged 5.7 ppb. These results are similar to the historical average (5.6 ppb).

Chlorophyll a concentrations greater than 10 ug/L are perceived as a mild algae bloom, while concentrations greater than 20 ug/L are perceived as a nuisance. Chlorophyll a was evaluated in Bass Lake in 2003-2011 (see Figure below). Chlorophyll a concentrations follow the phosphorus concentrations because phosphorus is food for the algae (see phosphorus results). Chlorophyll a concentrations are highest in spring and fall and lowest in the summer. In May and September, the lake is turning over and there is plenty of nutrients for the algae to multiply. Chlorophyll a concentrations in Bass Lake remained below 10 ug/L except for some dates in spring and fall, indicating clear water most of the summer. Chlorophyll a concentrations did not reach levels that are considered a major algae bloom on any of the sample dates from 2003-2011. However, in September, Bass Lake did have the highest Chlorophyll a concentrations during that time period.

Trend analysis shows that there is an increasing trend in chlorophyll a concentration from 2003-2011. More specifically, the algae concentration each August is increasing (99% probability), indicating algae blooms are getting worse each year. This could be due to the fact that much of the native vegetation in Bass Lake has been cleared and natural shorelines have been converted to mown lawns.

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