¹National Center for Water Quality Research, Heidelberg College, 310 E Market St., Tiffin, OH 44883, USA
²Current address: Northeastern Illinois Planning Commission, 222 S Riverside Plaza, Suite 1800, Chicago, IL 60606

*Corresponding author: prichard@heidelberg.edu

Summary

   Section 6217 of the Coastal Zone Act Reauthorization Amendments of 1990 (CZARA) requires that states develop and submit a Coastal Nonpoint Pollution Control Program. Management measures must be specified in state programs for restoring and protecting coastal waters from specific categories of nonpoint source pollution. Irrigation is one of several potential sources of agriculture-related nonpoint-source pollution. In this study, water withdrawals and returns within the Ohio Lake Erie Basin were evaluated to determine their potential impact on the water quality of Lake Erie, and support a policy choice by the State of Ohio: whether or not the water quality impacts are sufficient to justify implementation of the relevant Section 6217 management measures. Data for the years 1991–2002 included surface and groundwater withdrawal volumes, return flows, and number and type of users. Statistical and spatial analyses indicated that current levels of irrigation do not have a discernable impact on Lake Erie water quality. Net water use for irrigation is less than that for most industrial and municipal uses for which data were available. Other findings include important differences between water use for crops and nurseries, and upward trends in irrigation withdrawals, especially for nurseries. Spatial analysis reveals several areas of concentrated withdrawals. Future research should consider the seasonality of irrigation agriculture and other hydrological variables of interest, and focus on understanding the potential for local impacts of irrigation on surface and ground water resources.