Nitrate levels in Iowa streams ebb and flow with the calendar and the weather.

In the Raccoon River watershed, 50% of the annual precipitation falls from April through July. About 60% of the annual streamflow and 70% of the annual nitrate load (total mass) also occur from April-July. So, what’s the explanation behind these numbers?

Many times here in Iowa we hear that weather is the cause of poor water quality in our lakes and streams, especially in discussions about stream nitrate. Is there merit to this idea?

If we want to improve Iowa waters, then we must restore some of our lost ecosystem function. This includes wetland construction and restoration.

Over the past 10 years or so, many models have predicted increased nitrate concentrations in Iowa streams driven by the Renewable Fuel Standard (RFS). Recent water-quality monitoring data, however, reveal some surprising results.