Premium
Carlson's Trophic State Index is a poor predictor of cyanobacterial dominance in drinking water reservoirs
Author(s) -
FernandezFigueroa Edna G.,
Buley Riley P.,
Barros Mario U. G.,
Gladfelter Matthew F.,
McClimans William D.,
Wilson Alan E.
Publication year - 2021
Publication title -
awwa water science
Language(s) - English
Resource type - Journals
ISSN - 2577-8161
DOI - 10.1002/aws2.1219
Subject(s) - eutrophication , trophic state index , geosmin , phytoplankton , environmental science , water quality , dominance (genetics) , chlorophyll a , microcystin , trophic level , cyanobacteria , environmental chemistry , ecology , hydrology (agriculture) , nutrient , odor , chemistry , biology , botany , biochemistry , genetics , geotechnical engineering , organic chemistry , gene , bacteria , engineering
Abstract A 20‐month survey of 71 surface drinking water utilities across 44 waterbodies was conducted to determine whether the commonly used Trophic State Index (TSI) is a reliable indicator of eutrophication in drinking water sources. Raw water quality results showed that cyanobacteria, cyanotoxins (i.e., microcystin), and taste and odor (T&O) compounds (i.e., 2‐methylisoborneol and geosmin) were generally low in the utilities sampled. TSI values based on chlorophyll concentrations (TSI Chl‐ a ) were closely related to phytoplankton, cyanotoxin, and T&O concentrations and indicated that most drinking water sources were mesotrophic or eutrophic. However, TSI values based on total phosphorus (TSI TP) indicated that the drinking water sources were eutrophic or hypereutrophic. These results suggest that TSI Chl‐ a is a better predictor of cyanobacteria and their compounds than TSI TP. Phytoplankton abundance decreased with depth; therefore, managers should consider switching to deeper intakes when TSI Chl‐ a values increase to reduce removal costs.