> For the complete documentation index, see [llms.txt](https://swatplus.gitbook.io/io-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://swatplus.gitbook.io/io-docs/introduction-1/reservoirs/nutrients.res/untitled-1.md).

# chla\_co

The chlorophyll *a* concentration in the reservoir is calculated from the total phosphorus concentration. The equation assumes the system is phosphorus-limited. The chlorophyll *a* coefficient was added to the equation to allow the user to adjust results to account for other factors not included in the basic equation, e.g. nitrogen limitations.