LAND USE ANALYSIS OF BEAVER LAKE WATERSHED, NORTHWEST ARKANSAS

Northwest Arkansas is currently undergoing a period of rapid population growth. This boom is creating water quality problems for Beaver Lake. Approximately 1 in 8 people in Arkansas obtain their water from the 40,463 acre reservoir and in order to ensure quality water for the future it is imperative that protective measures be put in place to protect the watershed.

Analysis of the watershed was completed with the purpose of giving Beaver Water District the data necessary to appropriately manage the Beaver Lake Watershed. Environmental data layers were compiled using a geographic information system. The initial investigation of land use and land cover was made at the 8 digit HUC (hydrologic unit code) watershed level. Further analysis was then conducted at the 12 digit HUC watershed level. Using SSURGO soil data, maps of soil type, septic suitability and hydrologic soil groups were created. The presence or absence of riparian buffers along the lake and streams was also mapped. In addition, special emphasis was placed on 150 ft. buffer zones around streams and ¼ mile buffer zones around the lake in an attempt to emphasize these particular zones of possible contamination. The resulting data, once assembled, highlighted the areas where development should not occur.

The West Fork watershed (HUC 110100010404), containing south Fayetteville, is a sub-basin of Beaver Lake watershed. Fayetteville's population growth has created the need for construction, which exposes bare soil. As soil runs off these sites and into streams, the water quality drops. To give Beaver Water District the data to manage this problem, a secondary study was undertaken. Soil runoff was calculated using current and historic precipitation events. Combining soil characteristics and surface area yielded an area weighted NRCS Curve Number for each distinct soil type. This allowed for the soil runoff for the entire watershed to be calculated. In June 2005, during a period of drought, soil lost from bare soil areas alone was approximately 1.33 inches. These totals demonstrate the need for erosion control devices throughout the Beaver Lake watershed.

Ultimately the data provided to Beaver Water District will help enact regulations to keep the lake and its watershed in the best condition possible for the future.