Steep Slope Development in the Upper Catawba
There are many areas in the upper Catawba Basin that are being faced with increased development pressure. Many of these potential development areas are along steep slopes located in the headwaters of the drainage basin. Continued development in these areas will greatly increase the amount of runoff water and sediment entering the drainage basin. If steep slope development is left unregulated it can negatively impact the riverbed over time.
In steep slope development areas along the upper Catawba basin, runoff water carrying large amounts of sediment can cause many problems to the local watershed. The short-term effect of run-off water can cause creeks and streams to become extremely turbid. According to the 2010 Catawba River Basin Plan, a turbidity of 50 NTUs can classify a water body as impaired. There are currently twelve stream segments impaired for turbidity in the basin and the highest percents of these samples were located around developing areas.
Long-term effects of sedimentation can create shallow waters or in worst case scenarios irreversible blockage to certain portions of the river. The more development that is allowed in these steep slope areas the more severe sedimentation issues will become. There are a few regulations that developers are required to do to alleviate some run-off such as maintaining sedimentation fences and buffer regions. However, these methods are not enough to keep run-off and sedimentation from being a problem in steep slope areas. Currently, our Land Development Code permits construction of subdivisions on slopes up to 60%.
Land of Sky Regional Council Report:
The Land of Sky Regional Council prepared an article that explored all the negative impacts of developing on steep slopes including their effect on water quality, septic tanks, landslides, wells, roadways, sedimentation and erosion, storm drainage runoff, roadway maintenance, emergency response, ground water recharge, forest fires, etc. This report also stated that the steeper the slope the greater the need for a larger defensible distance between the trees and the home. From reviewing information available on this subject the overwhelming recommendation for developing on slopes is not to exceed 25%.
According to the Land of Sky Report in order to maintain and preserve steep slopes to reduce our impact on local watersheds we must abide by the following:
o In steep slope areas, impervious surfaces within the development tract should be limited to no more than 10 percent of the total project area and designers should avoid placing impervious areas on steep portions of the tract (WQ-1).
o At least 50 percent of the entire steep slope development tract should be preserved as forestland; areas within individual parcels and streamside protection areas can be included in this percentage (WQ-2).
o In steep slope areas, Streamside Protection Areas should be established on all perennial streams, intermittent streams and wetlands. Protection Area width should be based on the slope of the adjacent land (WQ-4).
o The State should provide additional resources to the NC Land Quality Section for additional staff in the Asheville Regional Office to increase inspections of land disturbing sites under the state’s jurisdiction (WQ-10). Local governments should consider adopting their own local erosion and sedimentation control programs (WQ-11).
o State and local governments should require all steep slope developments to submit comprehensive storm water management plans (WQ-16)
To read more about the Land of Sky Report click here.
How can you help protect your watershed from development pressures?
Join the Catawba Riverkeeper Foundation in writing letters, voicing opinions at Commission meetings, and collaborating with other organizations throughout the upper Catawba basin to regulate steep slope development practices and keep our water flowing clean and free.