ECOLOGICAL SERVICES RESTORATION PROJECT BLOSSOM WAY CREEK, ROGERS, ARKANSAS Morgan, R.A.; E. Cummings; S. Ekka; G. Goh; A. Ludwig; M. Matlock; A. McAllister; M. Nelson; B. Schaffer; C. Thompson Biological and Agricultural Engineering: University of Arkansas, Fayetteville ABSTRACT The City of Rogers, Arkansas is part of the rapidly growing metropolitan area of Northwest Arkansas. In June of 2003, the Milken Institute identified the area as having the top economic performance of cities in the United States. The water resources of the area have been stressed as the cities struggle to develop infrastructure to match the growth. Increased wastewater, stormwater runoff, and loss of riparian zone vegetation have all contributed to the stress. In 2002, the City received a section 319(h) nonpoint source pollution grant to demonstrate protection of ecological services (disturbance regulation, water regulation, water supply, erosion control, nutrient cycling, waste treatment, refugia, recreation and cultural uses) through the use of greenways. The demonstration is on a second order stream draining a roughly sixteen square kilometer watershed that is developing as commercial, industrial, and family residential property. In the initial phase of the demonstration, an evaluation was made of the riparian habitat, biodiversity, trees present, land use and land use change, and hydrologic/geomorphologic conditions in the stream to analyze the ecological services provided by the stream. The project is unique in its combination of environmental sciences and engineering in the initial planning stages. A local stakeholders committee has been established to extend the greenway concept to the rest of the city, and the city now requires new developments to dedicate floodplain property to the greenway system. Watershed Description Blossom Branch is located in Rogers, Arkansas and flows southwest into the Illinois River. The watershed area of interest is approximately 15.6km2; the reach of interest is approximately (,494m extending from Dixieland road downstream to 26th street. In addition, located at the 26th street bridge is a gauging station that provides the necessary hydrologic data for this greenway project. The average land slope of the watershed is 2.78%. Maximum width is 4.96km and maximum length is 5.67km. Land cover is a mixture ofrecreational, single family residential, industrial, highway commercial, residential, and agriculture. Stakeholder Involvement: The City of Rogers Chamber of Commerce formed a new Greenway and Trails Committee whose function is to oversee the development of a comprehensive greenways and trails program for the city including input to on the desires of the City concerning Blossom Way Creek. The landowners along the project area along with the City Parks and Recreation and Planning Departments and the Rogers Public Schools formed the second committee which will make final decisions on implementation of recommendations from the project. METHODS AND MATERIALS Watershed Delineation and Land Use/Land Change: The Blossom Way Creek watershed was delineated and land use estimated using ArcView GIS 3.2a (ESRI, Redlands, Ca.) using thirty-meter digital elevation models (DEM) from the United States Geological Survey (USGS). Habitat Assessment: Habitat assessments were performed at eight sites on the Blossom Way Creek between Dixieland and 26th street using the USEPA’s (1999) Rapid Bioassessment Protocols. Tree Survey: Individual trees were identified in the field by common name, estimated height, and estimated base diameter width. The data were entered into CityGreen v5.2. Aerial DOQQs from 2001 were used as a reference to label where individual trees are located. Reach Identification: The Blossom Way Creek was divided into three stream reaches that were representative of the stream segments. Reach 1 is grass banked with a relatively small channel. Reach 2 has increased flow, wider channel, and increased riparian zone timber. Reach 3 is wide highly eroded. Channel Forming Discharge: Three methods were used to compute channel-forming discharge, the 1.5-year return interval discharge was computed using the Natural Resources Conservation Service curve number method, from surveyed stream cross sections in each reach and compute the bankfull discharge using Manning’s formula, and by monitoring a bankfull event at the gage on 26th street. The three methods were compared and the channel-forming discharge selected using professional judgement. To compute the discharge of the stream with the NRCS method, an initial CN watershed was estimated as 75. The peak discharge for a 10 year recurrence event was then calibrated to the values given in the Federal Emergency Management Agency (FEMA) flood study for the site and CN adjusted accordingly. Sediment Transport: Total sediment transport in a stream was computed as the sum of the washload and the bedload. The suspended sediment concentration, as measured at the 26th street bridge was obtained from the Rogers Water Utilities. The average suspended sediment load for all storms with a gage height of greater than 4 feet was used as the estimate for washload at bankfull. For this study, bedload was computed by Einstein’s (1942) equation. Detention Storage: The required volume of detention storage was computed as the difference in volume of the hydrographs for bankfull discharge at 26th street for the predicted conditions and the estimated historic discharge. Historic discharge, the land cover was assumed as forest in good condition; and, the soil was hydrologic group B. PROJECT DESIGN COMPREHENSIVE DRAWING DISCUSSION Objective 1. Reduce tractive force and erosion by restoring channel sinuosity, reducing slope, and reducing bank height. Objective 2. Stabilize channel and prevent further entrenchment by installing grade control structures. Objective 3. Restore riparian buffer to provide terrestrial and aquatic habitat. Objective 4. Use abandoned channel as subsurface retention to treat parking lot runoff, and to supply minimum flow during low-flow periods. Objective 5. Restore pool riffle habitat by installing artificial riffles. Original Channel Constructing Subsurface retention cell Dredging New Channel Proposed Greenway Loop, Rogers, Arkansas Sediment Transport: SS Concentration639 ppm Wash load345 tons/day Bed load5,990 tons/day Total load6,335 tons per day