Vegetative filter strips have been demonstrated as a practical strategy in reducing soil loss and nutrient transport from agricultural land. Their environmental benefits need to be further tested in long-term field monitoring on a landscape scale. Twelve small agricultural watersheds at the Neal Smith National Wildlife Refuge in Central Iowa were used to evaluate the effectiveness of vegetative filter strips (VFS) in improving water quality in agricultural runoff. Four treatments with VFS of different size and location (100% rowcrop, 10% VFS at footslope, 10% at footslope and in contour strips, 20% VFS at footslope and in contour strips) were implemented in the watersheds in fall 2006 using a balanced incomplete block design. Nonperennial areas were maintained under a no-till 2-yr corn-soybean rotation since spring 2007. An H-flume was installed at the bottom of each watershed in 2005 to collect runoff from slope area. ISCO automated water samplers equipped with pressure transducers were installed in 2007 at each flume to record flow rate and collect water samples from April through October. Concentrations of total suspended solids, total nitrogen and total phosphorus were analyzed for surface runoff from 2007-2010. Our findings indicated that incorporation of small amounts of VFS within annual rowcrop systems provide an effective approach to improving water quality in runoff from agricultural landscapes.