Crooked Creek is in Grant County in northern Oklahoma, with its headwaters located just across the border in Kansas. Land use in the 130,000-acre watershed is primarily wheat production and grazing lands for cattle, with a small amount of corn production as well. Large tracts of cropland, coupled with poor grazing land management, contributed to excess sedimentation in the watershed. In the 2006 water quality assessment, monitoring showed that 20 percent of Crooked Creek?s seasonal baseflow water samples exceeded 50 nephelometric turbidity units (NTU). A stream is considered impaired by turbidity if more than 10 percent of the seasonal base flow water samples exceed 50 NTU (based on five years of data before the assessment year). On the basis of these assessment results, Oklahoma added Crooked Creek to the 2006 and subsequent CWA section 303(d) lists for nonattainment of the fish and wildlife propagation designated use due to turbidity impairment.
Landowners implemented BMPs with assistance from Oklahoma?s locally led cost-share program and through the local U.S. Department of Agriculture?s Natural Resources Conservation Service (NRCS) general Conservation Technical Assistance Program, Conservation Reserve Program (CRP) and Environmental Quality Incentives Program (EQIP). From 2006 to 2009, landowners reduced erosion potential from cropland with conservation tillage methods: nearly 6,000 acres of no-till, strip-till, and mulch-till, in addition to 1,856 acres of conservation crop rotations, 475 acres of residue management and more than 1,000 acres of cover crops. To slow erosion on sloped cropland, 35 acres of contour farming, 63 acres of grassed waterways, 73,661 feet of terraces and one grade stabilization structure were installed. Proper nutrient management was implemented on 2,125 acres of cropland. Project participants improved pasture and range conditions with 2,944 acres of prescribed grazing, installation of two ponds for alternative water sources, 9,680 linear feet of fencing, 3,243 acres of supplemental range planting and 4,200 acres of upland wildlife habitat management.
BMP implementation continues in the watershed. From 2010 to 2012, 6,421 acres of no-till and reduced-till crop production occurred, along with 41 acres of cover crops, 1,282 acres of conservation crop rotations, and 169 acres of forage planting and harvest management. Two more grade stabilization structures were installed, along with two diversions, 15 acres of grassed waterways and 9,168 feet of terraces. To optimize grazing conditions, landowners practiced prescribed grazing on 7,786 acres, planted supplemental vegetation on 46 acres, installed 12 watering facilities and two additional ponds, and managed 1,530 acres of upland wildlife habitat.
The Oklahoma Conservation Commission?s Rotating Basin Monitoring Program, a statewide nonpoint source ambient monitoring program, documented improved water quality in Crooked Creek due to landowners implementing BMPs. In the 2010 assessment, 0percent of seasonal base flow water samples exceeded the turbidity criteria of 50 NTU and Crooked Creek was removed from Oklahoma?s CWA section 303(d) list for turbidity impairment. Crooked Creek is now in full attainment of the fish and wildlife propagation designated use.