Illinois Fertilizer & Chemical Association
Supply · Service · Stewardship

Update on Nitrates and Lake Water Quality

Historically, April and May are the two months when nitrate levels in Illinois water supplies rise and can approach 10 ppm (the federal drinking water standard) or higher.  Lakes Decatur, Springfield, Bloomington/Evergreen and Vermilion are all surface water supplies that provide drinking water and therefore managing nitrate levels to keep them below 10 ppm is a high priority.  For the past 8 years, IFCA has worked with these water supplies to better monitor what is occurring in the lakes, and we keep our members in the watersheds aware of nitrate levels as we all work to improve nutrient utilization.   
This spring, only Lake Decatur has had to treat to remove nitrates; the N level there rose to 10.8 ppm in raw water in early April and the City of Decatur activated their nitrate removal system to ensure the water supply was well below that level in finished water.  As of mid--May, the levels have fallen to below 10 ppm and treatment has stopped.  Lakes Springfield, Vermilion and Bloomington all stayed below 10 ppm.  Peak nitrate levels in Lake Springfield this spring were 1.2 ppm, Lake Vermilion at 8.2 ppm and Bloomington at 8 ppm, but they too have dropped since then.  
IFCA's goal is for the fertilizer industry to continually educate and promote nitrogen management practices that keep this nutrient for the crop by promoting the 4Rs particularly the right rate and timing.  We continue to work alongside NREC to facilitate on-farm nitrogen rate trials that improve the Nitrogen Rate Calculator, to track the movement of soil nitrates, and to experiment on successful management of cover crops in our highly productive cropping system.  Visit the "Keep it 4R Crop" menu at for nutrient bulletins and nitrogen rate trial results.