The State of South Dakota performs water quality analysis on McCook Lake once every 4 years. This only takes into account one GPS point that they perform their sampling collections. The following parameters are analyzed by the State: pH, Dissolved Oxygen, Depth at sample site, Conductance, Water Temperature, Chlorophyll A, Chlorophyll B, Chlorophyll C, Clarity, Calcium Carbonate (water hardness), Fecal Coli Form, Ammonia, Phosphorus, Total Solids, and Total Suspended Solids.
More frequent water testing is currently funded by the McCook Lake Recreation Association in cooperation with the East Dakota Water Watch Group, McCook Lake Izaak Walton League, Missouri River 319 Grant funds and the City of North Sioux City. This funding and cooperation allows us to perform sampling once per month from April to October with microbiological samples during two rain events. 14 specific sites are sampled each month during the boating season, with the following data collected: Air Temperature, Water Temperature, Wind direction, Precipitation (last 24 hours), visible vegetation at sampling site, animals at sampling site, pH, Total Dissolved Solids, Location Depth, Water clarity, Dissolved Oxygen, Oxygen Reduction Potential, Conductance and water sample for Fecal Coli form.
The Collection of data allows the Lake Association to track changes to the lake and when negatives trending in results are noticed the State & Games Fish and Parks can be notified for investigation.