Use of real-time and continuous water quality monitoring in Iowa streams to inform conservation strategy in an agricultural landscape

Abstract:

Agricultural watersheds in the Midwestern U.S. are major contributors of nutrients to the Mississippi River Basin and the Gulf of Mexico. Many states within the Upper Mississippi River Basin, including Iowa, are developing nutrient reduction strategies to reduce non-point and point source loads of nitrogen and phosphorous in an effort to reverse degradation of streams and lakes.

Quantifying nutrient loads in Iowa and assessing loads transported within Iowa rivers are important components of Iowa's strategy. Nutrient loads estimated with data collected using traditional methods of grab sampling are expensive and have met with limited usefulness to the agricultural community when assessing the effectiveness of implemented conservation practices.

New sensor technology is allowing for real-time measurement of nutrient loads in many Iowa rivers. IIHR Hydroscience and Engineering has deployed 22 nitrate-nitrogen sensors in several Iowa rivers to provide accurate measure of nutrient loads. Combined with 17 sensors operated by the USGS, the sensor network captures nutrient transport and loading patterns in rivers across the state. A new Iowa Water Quality Information System (IWQIS) is being developed to display and share the continuous, real-time data.

The data reported here will compare and contrast load calculations obtained using continuous monitors with those from a more traditional grab samples. We also will demonstrate how continuous nitrate monitoring informs watershed hydrology and the assessment of conservation practices designed to reduce nutrient loss from farmed fields. Finally, we will establish that the costs of real time continuous monitoring are modest when compared to grab sampling strategies and the costs of implementing conservation on productive lands in the Western Corn Belt of Iowa.