Water Quality Component,
Long Term Resource Monitoring Program
As part of the Long Term Resource Monitoring Program (LTRMP), we have monitored water quality in the LaGrange reach of the Illinois River since 1989. From 1989-1993, we sampled approximately 25 fixed sites every week. In 1993 we switched to sampling once every two weeks at 13 fixed sites (including 5 major tributaries) and also to seasonally intensive sampling (i.e. four times per year) at up to 135 main channel, side channel, and backwater sites throughout the reach. These sites are chosen using a stratified random method. Also, we recently dropped 2 fixed sites and changed our sampling frequency due to funding issues. We now sample fixed sites bi-monthly April-June, monthly in January, March, August, September, October, and November and no fixed site sampling takes place in February or December. Stratified random sampling (SRS) still takes place as it has since 1993 with the exception of 2002 when no SRS was done.
Some of the parameters that we measure in the field at these sites include depth, secchi, temperature, dissolved oxygen, conductivity, pH, and velocity. A water sample is collected and taken back to the lab and analyzed for turbidity, suspended solids, chlorophyll, and phytoplankton. Other water samples are collected, preserved, and later analyzed in a lab for different nutrients such as total nitrogen and total phosphorus just to name a few.
