Mark David of the University of Illinois noted that there was good understanding of nutrient and water quality trends “directionally,” but that better scientific information was required at the watershed scale. He noted that a key limitation in conducting studies at watershed scale is access to private land and participation by landowners. He further noted that even when studies can be conducted at the watershed scale, there is a challenge of obtaining a pre-development or pre-activity baseline record. He also discussed the importance of individual landowners’ perceptions of nutrients and water quality, wondering how to better engage those parties who may not perceive any issues or problems regarding water quality. He noted a major issue is how to help pay, and/or regulate, private landowners in order to achieve watershed-scale response. He noted that landowners have installed more tile drainage and put more land into production in the last few years (presumably because of expiration of conservation easements and rising prices for commodity crops, such as corn).

Matthew Helmers of Iowa State University discussed the importance of tracking practices on the land. He noted that there has been useful work done in this regard with remote sensing, but emphasized that detailed data about agricultural practices are needed (e.g., data on rate, locations, and timing of nutrient application).

Douglas Schnoebelen of the University of Iowa discussed the importance of using numerical modeling to help understand riverine processes at different scales. He emphasized the importance of integration of models designed for different scales in order to understand watershed scale processes and effects.

Lori Sprague of the U.S. Geological Survey expressed the view that there are good examples for monitoring at different scales and across state boundaries. She cited the monitoring of the Susquehanna River as part of the Chesapeake Bay Project as a notable example. This monitoring effort involves multiple states and multiple government agencies, but is conducted in a coordinated manner and with consistent methods. She discussed ongoing challenges associated with interpreting the causes of trends in water quality data for nutrients and other contaminants, and that more ancillary data on environmental conditions and flows are needed to interpret trends in water quality data. She also noted the complications involved in determining sources and relative values of nutrient inputs, explaining that this is not simply a matter of subtracting municipal and industrial loads (point sources, with relatively accurate and reliable data) from total loads in rivers, then attributing the rest to agriculture.

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