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Water: Nonpoint Source Success Stories

Section 319 Success Stories, Vol. III: Tennessee

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Ghost River Land Acquisition Project:
River Protected by Restoring Forested Wetlands

 

Contact:
Reggie Reeves
Tennessee Department of Environment and Conservation
Division of Natural Heritage
8th Floor, L&C Tower
Nashville, TN 37024
615-532-0434

Primary Sources of Pollution:

  • agriculture
  • logging
  • channelization


Primary NPS Pollutants:

  • sediment
  • nutrients


Project Activities:

  • riparian reforestation
  • wetland restoration
  • cattle exclusion


Results:

  • acquisition of more than 1,500 acres for long-term protection of riparian and wetland habitats

The Ghost River region of the Wolf River is part of the larger Wolf River Conservation Initiative. The Wolf River is an unchannelized river in west Tennessee extending from the Mississippi-Tennessee state line in Fayette County to Memphis, where it becomes channeled in Shelby County. The Ghost River section begins at the bridge at LaGrange and continues to Bateman's bridge approximately 10 miles to the west. This section of the Wolf River features a meandering river channel, a swamp forest where the river channel is braided, and an open swamp lake. The banks and parts of the river are forested, which provides significant wildlife value. The overall water quality is considered good because the river supports many species of filter-feeding mussels.

The significance of the Ghost River region relates to its unaltered channel, which supports important forest communities in need of protection. These communities are bald cypress, water tupelo, and bottomland hardwood forests. The Wolf River has numerous recreational uses that are compatible with natural area preservation. They include hunting, fishing, canoeing, birding, and other nature appreciation activities. Education and research are encouraged and might be important parts of the management to restore bottomland hardwood forests and buffer areas.

Increasingly, land along the Wolf River is being cleared of natural bottomland hardwoods and other wetland vegetation. Much of the watershed is under agricultural production, which contributes significantly to increased sedimentation in the river and loss of riparian and wetland habitats. In many places along the Wolf River, cattle access the river and associated wetlands, causing additional erosion. Primary threats to the river include forest fragmentation and erosion from logging, channelization, contamination and erosion from agricultural use, pollution caused by dumping, and urban sprawl. There are also other threats, such as noise and toxic pollution from motorboat use in the swamp lake, off-road vehicle use, and the introduction and spread of invasive exotic species. Any use of invasive exotic plant species in food plots in the adjacent Wildlife Management Area could pose a threat.

A three-phase project

The Ghost River Initiative sought to prevent these threats to the Ghost River section of the Wolf River by acquiring land and establishing conservation easements to protect and enhance water quality. The tracts identified for acquisition flood annually and have a high potential for wetland and riparian habitat restoration with associated water quality improvement.

To accomplish riparian habitat conservation and wetland habitat restoration on the Ghost River, a three-phase project was developed. First, property would be purchased. Second, with cooperating organizations, a plan would be developed for thorough restoration of the tracts, including riparian reforestation, wetland restoration, and cattle exclusion. The third phase would involve implementation of the restoration work in association with cooperating organizations. Support for this project included $250,000 in section 319 funding, plus $284,755 in match.

Results and other efforts

More than 1,500 acres have been purchased in the Ghost River section for long-term conservation of the riparian and wetland habitats. These properties are, for the most part, adjacent to one another. The Ghost River Initiative represents one of many conservation projects under way to protect the Wolf River. Other efforts continue to protect the area through acquisition, conservation easements, registry agreements, or other forms of cooperative management agreements.

Management and restoration plans for the area are under development. Subject to other funding, the Tennessee Department of Environment and Conservation, Division of Natural Heritage, will complete a biodiversity field review of the properties for use in the development of a comprehensive management and restoration plan.

The restoration of bottomland hardwood forested wetlands is important in Tennessee because of the decline in this category of wetland habitats. Efforts will continue to ensure that this unique river system is preserved in its natural state for future generations of Tennesseans to enjoy.


 
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Using Constructed Wetlands to Clean Up Pesticides:
Container Nurseries Will Benefit from Successful Pilot-Scale Study

 

Contact:
Dr. Kim Stearman
Tennessee Technological University, Water Resources
Box 5033
Cookeville, TN 38505
931-372-3528
gkstearman@tntech.edu

Primary Sources of Pollution:

  • container nurseries


Primary NPS Pollutants:

  • pesticides
  • nutrients


Project Activities:

  • constructed wetland


Results:

  • removal rates greater than 80 percent for herbicide, 90 percent for nitrogen, and 85 percent for phosphate

Container nurseries account for an increasing share of total nurseries in Middle Tennessee. The nursery industry is concentrated in that part of Tennessee and ranks in the top 10 agricultural industries in the state each year. Container nurseries traditionally apply large amounts of pesticides and nutrients to the nursery crops, which are susceptible to runoff into surface waters. Collection ponds have been used with some limited success, but pesticide or nutrient residues can concentrate in the ponds because little if any treatment to remove harmful substances is used.

Although constructed wetlands have not been evaluated for use in container nurseries, Tennessee Technology University's Water Center has used such wetlands to treat the town of Baxter's wastewater, and the wetlands have been operating successfully for several years. This site was ideal for incorporation of a container nursery to demonstrate constructed wetland treatments because the nursery was in place and operational.

Project goals

The primary goal of the project was to demonstrate constructed wetlands as a cost-effective best management practice to reduce pesticide and nutrient runoff and to purify water in container nurseries. The specific objectives were to (1) determine removal rates of simazine, metolachlor, nitrogen, and phosphorus from container nursery runoff using constructed wetland cells; (2) determine the effect of vegetation (soft-stem bulrush), flow, depth, and aspect of constructed wetlands on herbicide and nutrient removal; and (3) design and install a pilot-scale, subsurface-flow gravel constructed wetland at a container nursery grower's site for removal of herbicides and nutrients and for demonstration to growers and other interested parties.

In the spring and summer of 1998 and 1999, a field study was conducted at the Baxter, Tennessee, wastewater treatment plant, where constructed wetland cells have been studied since 1992. A 450-square-meter container nursery with overhead irrigation was built on-site. Water runoff from the container nursery was pumped into 14 gravel subsurface-flow constructed wetland cells. Bulrush (Scirpus validus) was grown in seven of the cells, and seven cells had no plants. The wetland cells were either 30 or 45 centimeters in depth. Three loading rates of runoff water containing herbicides and nutrients were added, corresponding to hydraulic retention times of 2 to 21 days. The removal of herbicides (simazine and metolachlor) and nutrients (nitrogen and phosphorus) in each of the constructed wetland cells was calculated and correlated with bulrush vegetation, loading rates, depth of cell, and hydraulic retention time.

Promising results

Constructed wetland cells with plants removed significantly more simazine, nitrogen, and phosphorus than cells without plants. Cells with plants removed more metolachlor at 2- to 8-day retention times, but at higher water retention times there was no difference. Nitrogen removal was greater in the cells 45 cm deep (89 percent) than in the cells 30 cm deep (76 percent). Depth did not affect herbicide or phosphorus removal. Removal of simazine ranged from 57 to 96 percent, and metolachlor removal ranged from 18 to 95 percent of that applied; no significant difference in removal was seen between the first year and second year of the project. In constructed wetland cells with plants, about 60 to 65 percent of herbicides were removed at the high loading rate, which was equivalent to a 2- or 3-day hydraulic retention time. Increasing the retention time to 8 or more days improved herbicide removals to above 80 percent in the cells with plants. Nitrogen removal was greater than 90 percent in all vegetated cells. Phosphate removal was greater than 85 percent in all vegetated cells except one cell, which had the shortest retention time.

A newly constructed wetland might require some time for plants to become established, thus affecting removal efficiencies. The system at Baxter was a mature system, with wetland bulrush plants established since 1992 and plant densities greater than 300 stems per square meter. A pilot, subsurface-flow gravel constructed wetland has been installed at a nursery in Smithville, Tennessee, and is being evaluated for operation, maintenance, and removal efficiencies. A workshop and demonstration of the constructed wetland took place on October 24, 2000, at the Pirtle's Nursery site. There was a good turnout of nursery growers, and many of the growers showed a high interest in the technology.


 

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