CARLSON'S TROPHIC STATE INDEX (TSI)

A measure of Eutrophication of a body of water using a combination of measures of water transparency or turbidity (using Secchi Disk depth recordings), Chlorophyll-a concentrations, and total phosphorus levels. TSI measures range from a scale 20-80 and from Oligotrophic waters (maximum transparency, minimum chlorophyll-a, minimum phosphorus) through Mesotrophic, Eutrophic, to Hypereutrophic waters (minimum transparency, maximum chlorophyll-a, maximum phosphorus). Also referred to as the (Mean) Trophic State Index (TSI). Also see Total Inorganic Nitrogen (TIN) and Total Inorganic Phosphate (TIP).