Chlorophyll-a Offsets

Chlorophyll-a offset classes
Chlorophyll-a offset classes based on the data distribution

Chlorophyll-a targets are maximum annual medians or geometric means requiring that data be at or below the target to meet the requirements. Chlorophyll-a offsets established for each target by year and for the period of record (POR) are positive if they meet or are lower than the target and negative if they exceed the target concentration.

The central tendency (median and geometric mean) was calculated for each station for each year as well as the POR. Offsets from the target data were calculated from the central tendency and data were averaged for each sublagoon annually and for the entire twenty years. The frequency distribution of the data, as shown in the figure, provided guidance to create chlorophyll-a scores.

Chlorophyll-a Offsets