Swannanoa River Watershed
In 2001 RiverLink embarked on an opportunity to develop a watershed wide approach to stormwater management to improve the water quality in the Swannanoa River Watershed, through treating non-point source pollution in stormwater BMPs and two stream restorations. The Swannanoa River is a major tributary to the French Broad River, travelling 22 miles to the confluence at the Biltmore estate in Asheville. Its headwaters begin in Black Mountain and include the North Fork and Bee Tree Reservoirs, which supply drinking water to Asheville and other Western NC residents.
In 1998 the NC DENR Division of Water Quality (DWQ) identified water quality issues within the Swannanoa River Watershed, resulting in poor water quality in portions of the river. Residential and commercial development over the recent decades has contributed to poor water quality in the Swannanoa, due to an increase in sedimentation and sediment- laden runoff. The 2005 French Broad Basin Plan identified habitat degradation, poor-quality riparian buffer zones, nutrient enrichment, sedimentation, channelization and toxicity as water quality problems in the Swannanoa River watershed. In 2006, two segments, totaling 14 river miles were added to the EPA impaired streams list and remained on the list until 2011. In 2011 NC DWQ removed the Swannanoa River from the impaired streams list, due to improved water quality and reduced sedimentation in the river. The stream restorations and stormwater BMPs implemented through RiverLink watershed wide approach to treating non-point source pollution where a major contributing factor in the improvement of water quality. These projects all treat non-point source pollution in the watershed, but they also provided an educational resource and proven examples from which others can learn from and implement themselves.
Azalea Park – Swannanoa Stream Restoration
RiverLink as part of this effort developed and implemented one of the largest stream restorations in Western North Carolina. With support from the Clean Water Management Trust Fund, the City of Asheville, Azalea Park area residents, and a team of engineers, RiverLink restored approximately 1.5 miles of the Swannanoa River though Azalea Park. The goals of the project was to stabilize and protect stream banks along 1.9 miles of the main stem of the Swannanoa River, to improve water quality and aquatic habitat, and protect and enhance riparian buffers (avg. 150 ft.) through conservation easements.
Azalea Park and the John B. Lewis Soccer Complex is a 155 acre city owned property in East Asheville on Azalea Road. It is sure to be one of the most utilized parks within the city. With four soccer fields already installed and a master plan that includes baseball fields, it’s important to recognize there is another side to Azalea Park that attracts fishermen, birders, runners and bikers.
RiverLink participated on the park design committee and felt a need to enhance and protect the natural resources that exist within the park. A logical choice was the Swannanoa River. The main stem of the river flows through the Blue Ridge Parkway property and dissects the park for over a mile. Unfortunately, over time, the river has been abused. It was moved over time to make way for agriculture in the valley, its riparian buffer has been severely diminished in size, and upstream development have taken its toll by adding to the amount of stormwater runoff received.
These changes over time have resulted in severe bank erosion increasing the amount of sediment input to the stream, while lack of sufficient riparian buffers has caused steam temperatures to warm in these hatchery supported trout waters. Both of these have significantly impacted the ability of trout to reproduce in the Swannanoa River. RiverLink received grant monies from the North Carolina Clean Water Management Trust Fund to help stabilize banks and improve riparian habitat throughout Azalea Park.
RiverLink, City of Asheville, Wolf Creek Engineering, and North State Environmental completed a priority II restoration on 1100 linear feet of stream, and stream bank enhancement and stabilization of 2000 linear feet of stream. Much of the in stream work will focus on redirection of stream flows from eroding banks and to create, a series of pools and riffles in appropriate sequences. This will decrease the amount of sediment entering the stream and increase the amount of oxygen in the water. This along with the root wads and logs that will placed in the stream will greatly enhancing aquatic habitat.
A 27 acre conservation easement along both sides of the Swannanoa will help to preserve new buffer plantings and protect them until maturity. A 7.8 acre wetland is also located at Azalea Park, an old oxbow of the Swannanoa cutoff many years ago. This is an excellent sight for birders looking for migratory fowl as well as waders. This area will also be protected with a conservation easement preserving it for future generations.
Swannanoa Stormwater Improvement Project
We received a cost share grant funds from North Carolina Department of Environment and Natural Resources Department of Water Quality/319 Non Point Source Pollution Section to implement phase I which includes 4 urban “best management practices”(BMP’s) and a small stream restoration, to treat nonpoint source runoff from urban areas within the Swannanoa watershed. Non-point source pollution, such as oil from parking lots, fertilizers, pesticides, and sediments is a major threat to the health of our waterways, but by using these BMPs local residents can greatly reduce the amount of pollution that reaches our streams. The goal of these projects is to provide examples and educate residents, developers, and local governments about preventing non point source pollutants from entering our streams and rivers. Five projects have been installed within in the watershed to demonstrate a variety of measures that can be replicated. These include rain gardens/bio-filters, stormwater wetlands, vegetated swales, stream bank stabilization, rain barrels, conservation easements, and riparian plantings. Below are examples of the “best management practices” that are now a model for treating water quality in the Swannanoa River Watershed. (Click here for the driving tour)
Charlie Bullman Athletic Facility, Haw Creek
Sections of Haw Creek were previously straightened to accommodate development, eliminating much of the natural pool and riffle structure that occurs naturally adding oxygen to the stream. The first phase of this project reconfigured the flow pattern of a section of Haw Creek, creating a more meandering pattern to allow more pools and riffles. This not only provides for a more stable stream but also increases biodiversity of habitat for associated aquatic species. Following reconstruction, native riparian plants were planted to help stabilize the stream bank.
The second phase of this project will address sediment runoff from the athletic fields. Sediment is the number polluter in the French Broad River Watershed. This past season approximately 6-8 dump truck loads of clay were needed to maintain the ball fields. This project will eliminate much of the sediment that is currently reaching Haw Creek by using vegetated swales and bio- retention cells to filter the sediment before it reaches the stream.
This site has excellent educational possibilities with students from Haw Creek Elementary and Evergreen Community Charter School within walking distance. This project will provide educational signage and access points for stream related learning experiences.
Evergreen Community Charter School
50 Bell Rd, Asheville, Please check-in at school office
The Evergreen Community Charter School project is designed to direct roof runoff from the main facility into a rain garden that can serve dual purposes. The rain garden will provide treatment of roof runoff which contains nutrients such as nitrogen, as well as enhance the educational opportunities for the science base curriculum (i.e. butterfly garden). The parking lot will be sloped to capture and treat stormwater containing gas and oil contaminants in a vegetated swale into a rain garden.
Both systems are designed to capture the first inch of rainfall, which contains the vast majority of pollutants. Overflow from both of these systems, in addition to runoff from roadways will be directed to another vegetated swale to reduce the water’s velocity and treated again in a stormwater wetland. The wetland will provide for additional educational opportunities by providing another biological habitat on campus for scientific studies.
Jones Residence, Haw Creek Community
The Jones property is bisected by Haw Creek and one of its tributaries. Until now, stormwater runoff from Haw Creek Road has flowed through their property unabated into Haw Creek. A stormwater wetland has been designed to stop direct input into the stream. The wetland is designed to allow the water to slowly pass through the wetland before discharging and is heavily vegetated with native wetland plants. By slowing the water’s velocity and allowing for some percolation, nonpoint source pollution entering the stream is greatly reduced.
Streambank erosion is a problem for many areas of Haw Creek where vegetation is sparse. The second phase of this project will be to remove invasive exotic plant species from the riparian buffer areas and then replant with native trees, shrubs and groundcovers. This will will stabilize the stream bank reducing sediment loading and providing shade to help maintain cool water temperatures.
Black Mountain Well Lot behind Arts Center
225 W State St, Black Mountain
Two bio retention cells (rain gardens) will treat roof runoff from adjacent buildings (Black Mountain Center for the Arts and the Swannanoa Valley History Museum). This runoff will be collected and filtered by soil percolation in the two landscaped bio-retention cells. The parking lot will be graded, sloped, and resurfaced to allow for stormwater runoff to be treated in a vegetated swale that will function to slow the runoff velocity. This will remove sediment and the associated parking lot pollutants (i.e., grease, oil, gas, and heavy metals like zinc, cadmium, etc.)
RiverWalk Park, Black Mountain, Behind Bi-Lo Grocery
205 Nc Highway 9, Black Mountain
This project was designed to treat stormwater runoff from half of the Bi-Lo roof and parking area. A bio-retention (rain garden) was installed to capture and treat runoff from approximately 1.5 acres of impervious surface. This runoff contains oils, grease, gasoline and sediment. The bio-retention cell was sized to capture the first inch of rainfall and allow sediment and nutrients to settle and filter through soil for approximately 24-48 hours. This will slowly release stormwater and capture pollutants. Sediment is deposited within the bio-retention cell and pollutants are bonded to soil particles.
An additional bio-retention area and a stormwater wetland were constructed onsite to treat stormwater runoff from the adjacent railroad. Appropriate native wetland plants were used on all projects to provide for nutrient uptake and aid in the decomposition of pollutants. All of these projects were designed to both educate and demonstrate new stormwater treatment technologies for students, developers and decision makers.