The Internal Phosphorus Calculator

Picture of Summer in Lake County's Lakes

Phosphorus is a key nutrient for plants and algae. With too much phosphorus, especially internal loading, algae can quickly grow out of control, turning water green and turbid.

Addressing phosphorus ranges from phosphorus-binding treatments to preventing internal loading at the source by limiting external runoff.

By quantifying internal loading in your lake, even as an estimate, you can make informed, impactful management decisions.

Methods for Estimating Internal Loading

It is always best to use data that represents your lake's current conditions. All methods require basic morphometry (average depth and surface area) and water column total phosphorus, which are pre-filled automatically for Lake County Lake Lovers monitoring lakes. The following methods are listed in order of confidence, with the most reliable method listed first.

1

Sediment Total Phosphorus

Calculated using total phosphorus concentration measured in lake sediment

Required Data: Sediment Total Phosphorus
2

Current Seasonal Water Column TP

Calculated using the current seasonal average total phosphorus concentration in the water column

Required Data: Current year seasonal Total Phosphorus values
3

Current Seasonal Secchi Depth

Calculated using current seasonal average secchi depth

Required Data: Seasonal Secchi Depth measurements
4

Historical Water Column TP

Backup calculation using historical seasonal average water column TP when no current data is provided

Required Data: None (Pre-filled automatically)

Entering as much supplemental data as you have produces a more complete range of estimated loading values.