Conclusions, Areas of Concern and Next Steps
The quality of the water in local rivers and streams flowing into Lake James is generally reflective of the land use and land cover within the watershed. Many of the streams and rivers in the Lake James Watershed originate in Pisgah National Forest and other public lands which are predominantly forested areas. As such, they are protected from development and major land disturbance, which has, in general, protected water quality in the watershed from severe degradation, so far. There are several Hydrologic Units (HUs) in the watershed that have permitted industrial and domestic waste point source discharges, including Mackey Creek, Tom’s Creek, North Fork of the Catawba and the Upper Linville River. These areas may be most likely to show water quality degradation and require monitoring for chemical and biological health. Information about prior chemical monitoring is available here. LJEA intends to focus its chemical and biological monitoring on the most threatened areas of the watershed.
In 2011, approximately 83.3% of the watershed was classified as “Forest.” Approximately 7.8% of the watershed was classified as “Developed” in 2011, an increase of over 560 acres from 2001. The watershed, in aggregate, is well below the level of development and impervious surface that is generally associated with significant water quality degradation. The LJEA analysis indicates that the trend between 2001 and 2011 was adverse to water quality, but that the change was relatively small. Unfortunately, the Lake James Watershed experienced significant degradation in its riparian zones, the most sensitive areas in terms of water quality impact, between 2001 and 2011. There were 228 acres of forest lost and over 200 acres of newly developed land within the watershed’s riparian zones. Most of the riparian zone degradation occurred near Lake James. In that Hydrologic Unit (HU), the Developed land increased from 8.0% to 11.3% between 2001 and 2011. With the acceleration of development since 2011, it is likely that the percentage of Developed land in the HU is approaching, or has surpassed, 15%. Although that percentage of Developed Land is below the value where significant, adverse water quality impacts occur, much of the development and impervious surface is immediately adjacent to Lake James and the small streams that feed directly to it. The loss of the riparian zone means the loss of the protective barrier that naturally prevents pollutants from entering the water. It is also important to note that the impact of development on water quality is not felt immediately. Even if development were to remain stagnant from now on, there will still be a decline in water quality in the next couple of years. If development in the area accelerates without proper management and design, the watershed will see accelerated decline in water quality.
There are two HUs that have greater than 15% of their area classified as Developed (Tom’s Creek and Upper Linville). There are five HUs that have Agriculture, Grassland & Shrub classifications exceeding 10% of their area (Crooked Creek, Mackey Creek, Tom’s Creek, Catawba/Lake James, and Upper Linville). High levels of Developed land and Agricultural use are often associated with water quality degradation. The riparian zones in the Lake James Watershed are generally more highly impacted by development and agriculture than the rest of the watershed. The HUs with the most highly impacted riparian zones are: Catawba/Lake James, Tom’s Creek, Upper Linville, Crooked Creek and Mackey Creek. Three of those HUs showed little change in land cover between 2001 and 2011 (Upper Linville, Crooked Creek and Mackey Creek). The other two (Catawba/Lake James and Tom’s Creek) showed significant land cover changes that adversely impact water quality.
LJEA has been monitoring water quality in the Lake James Watershed for the past 17 years. This watershed assessment report is an important step towards reevaluating the monitoring program with an expectation that LJEA will develop and customize biological, chemical, and physical monitoring plans to address potential adverse water quality impacts originating in areas of concern, including the Catawba/Lake James, Tom’s Creek, Upper Linville, Crooked Creek and Mackey Creek HUs.
One specific follow-up is LJEA’s commitment to update the analysis when more recent, comparable data becomes available in the National Land Cover Database. When that occurs, LJEA expects to address one deficiency in the analysis of riparian zones. The current analysis looked only at land cover and changes within 100 meters of the major tributary in each HU. That may understate the severity of land cover changes on water quality because it ignored what has occurred along smaller tributaries. That deficiency will be addressed in the updated analysis.