AskIFAS Powered by EDIS

A Beginners Guide to Water Management—Color


Aside from water clarity, the color of water in a lake is one of the main attributes that captures people's attention—particularly if the color begins to change. As this circular explains, changes in color can affect the biological productivity of a waterbody including the abundance of aquatic plants and/or algae. However, readers will also learn that most of these changes are the result of natural processes that occur within the watershed. Related topics of discussion include apparent color, true color, suspended and dissolved substances, along with the dynamics of light refraction. The last section provides two empirical models (equations) that can be used to determine if color in a waterbody is the result of algae or suspended solids. 32 pages in length. Chapter headings:

  • Part 1 Two Ways to Define Color in a Waterbody
  • Part 2 More About Suspended and Dissolved Substances
  • Part 3 Light and Color in Water
  • Part 4Color and Its Influence on Algae and Aquatic Plants
  • Part 5 Color, Water Clarity and Algae
  • Appendix 1 How to Use an Empirical Model

Keywords: algae, algal matter, antilogarithm, apparent color, aquatic plants, Botryococcus, chlorophyll, colloidal substances, color, common logarithm, diatoms, dissolved substances, emergent plants, empirical model, floating-leaved plants, humic acids, inorganic matter, light, light absorption, light attenuation, logarithm, long-term color changes, measuring true color, nitrogen, non-algal matter, non-organic matter, nutrients, organic matter, PAC, PAR, Percent Area Covered, Photosynthetic Active Radiation, PVI, Percent Volume Inhabited, pollen, phosphorus, platinum cobalt units, Secchi depth, Secchi disk, submersed aquatic plants, suspended substances, total chlorophyll, total nitrogen, total phosphorus, true color, tannins, Tsala Apopka Chain-of-Lakes, turbidity related color, visible light, water clarity, watershed

Note: Circular 108 is available in Portable Document Format (pdf) only. It can be obtained as a single PDF file by clicking on the "Printer Friendly Version" link above (file size = 2.6 MB).

Photos used with permission as credited.

Publication #Cir108

Release Date:November 17, 2020

Reviewed At:October 25, 2022

Fact Sheet

About this Publication

This document, CIR108, is the eighth of a series of information circulars dedicated to familiarizing citizens with the language and techniques used by those involved in water management. © January 2004, 1 st Edition. Reviewed by Mark Hoyer June 2020. Printed copies are available through the UF/IFAS Extension EDIS website and also from the Florida LAKEWATCH website Readability grade level: 12.0

About the Authors

Florida LAKEWATCH (FLW) is a research and public outreach program coordinated within the UF/IFAS Department of Fisheries and Aquatic Sciences. FLW facilitates public involvement in the management of Florida waters by training citizen volunteers to collect monthly water samples, algae samples, and water clarity data from a lake or waterbody of their choice. Over time, this information is used to document nutrient levels and/or to predict biological productivity. For more information about the program or to obtain FLW data, call 1-800-LAKEWATch (1-800-525-3928) or view the website at


  • Mark Hoyer