How is it measured?

To measure the color of lake water, scientists first take an epilimnetic core sample (the same that is taken for chlorophyll and total phosphorus). Then they filter it to take out all of the larger particles like algae. Usually scientists use the water sample left after the chlorophyll has been filtered out of the water in the chlorophyll test to use for the color test. This sample is placed in a spectrophotometer which is able to analyze the color reflectance within the visual light spectrum.

Dissolved Organic Carbon
Dissolved Organic Carbon is measured for a water body by first taking a water sample near the surface of the lake. Scientists are sure to rinse the bottle three times before the sample is taken. The sample is placed in a cooler and brought back to the laboratory for analysis. In the lab, a machine performs a series of tests on the sample. Dissolved Organic Carbon can be broken down into two categories,total inorganic carbon (TIC) and total organic carbon (TOC). The amount of total inorganic carbon (TIC) and total organic carbon (TOC) are determined by a process known as wet oxidation. TIC is determined by measuring the carbon dioxide released when a sample is acidified. The carbon dioxide is purged from solution and detected by and infrared detector. After the sample has been acidified and purged of TIC, sodium persulfate is added and the digestion vessel is heated to 100 C. The organic carbon is is oxidized to carbon dioxide, which is purged from solution and detected by an infrared detector.