Implementing landscape indices to predict stream water quality in an agricultural setting: An assessment of the Lake and River Enhancement (LARE) protocol in the Mississinewa River watershed, East-Central Indiana

Abstract

This study addressed the potential ability to link landscape indices to stream water quality in a predominately agricultural landscape located in the Mississinewa River watershed, East-Central Indiana. A methodology for developing and analyzing landscape indices using a GIS and remotely sensed and geospatial data was applied to 30 Hydrologic Unit Code (HUC) 14-digit subwatersheds. Six indices, three representing natural area extent characteristics and three representing natural area disturbance characteristics were developed. The resulting indices were then tested to determine if they could be linked to water quality variables (Total Phosphorus, Nitrate, E.COLI, and macroinvertebrate [EPT/C] Ephemeroptera, Plecoptera, and Trichoptera/Chironomidae scores). These variables were gathered from a database of diagnostic studies that only called for a single grab sample during a storm event and a base flow. Using this data provided an opportunity to test the quality of using single grab water samples as response variables. Regressions were not found to be significant for any of the four water quality variables. The findings provoked a discussion on the need for managing variation in water quality samples when attempting to develop successful linkages between landscape indices and stream conditions.