Parks and Recreation received an update Tuesday morning on data from studies performed for watershed conservation efforts at Lake Leatherwood. Parks Director Sam Dudley was joined by several other experts that assisted in collection of data, with the project working to identify problems at the lake including sediment accumulation, invasive vegetation species, water quality and proposed remedies on how keep the lake functional as both a place of recreation and conservation.
Graham Thompson, the senior design engineer at the Watershed Conservation Resource Center, a non-profit that helps protect and restore natural resources by providing technical and planning assistance to landowners and communities, began saying that technical planning with experts was needed now that much of the data collection was completed. These studies were funded by a 319 grant.
Both Dudley and Lake Leatherwood Manager Juanita Drought covered how the Parks Department had worked on clearing recreation areas at the lake from invasive plant species. Drought mentioned that the marsh areas around the lake are still filled with invasive species. Both she and Dudley mentioned in the meeting that the goose population that resides at the lake is still a problem and management attempts had not been successful.
Sandi Formica, executive director of the WCRC and attending by phone, mentioned that she was impressed with Parks’ work to clear recreation areas as well as had been done.
Among the studies conducted were a watershed study that screened for sources of sediment and nutrients moving into Lake Leatherwood as well as monitoring erosion in streams that feed the lake. Thompson explained that nine eroding stream banks contributed to 35 percent of sediment yield from stream sources, with those sources being the majority of sediment yield into the lake, contributing 77 percent in a year.
Kelsey Criswell, Water Resources Engineer at Olsson, the company contracted to conduct water quality studies on the lake, covered possible solutions to sediment buildup in the lake and pros and cons to each. She mentioned biodredging, where oxygen is introduced to a hypoxic setting that will allow introduced enzymes to break down organic sediment. She mentioned that the lakes sediment is currently 20 percent organic where normal sediment is around 3 – 5 percent.
Criswell explained that the use of biodredging might only prolong the time before traditional dredging methods are needed such as mechanically dredging the lake. There’d also be a need for power sources to keep compressors running to introduce that oxygen into the lake.
Mechanically dredging the lake would require drawing down the lake 10 feet to remove sediment but would require that sediment be left to dry out for 8 – 12 months. That raised concern about affecting use of the park, as well as the expense of removing sediment. Criswell said that it is effective at resetting the lake but does nothing to address underlying causes.
Hydraulic dredging would be similar, using pumps to bring wet sediment out of the lake, letting it drain and then removing it. She mentioned that there was no suitable location in size for the drain field that would be needed for the amount of sediment in the lake, saying that the campsite was closest.
She also covered other management options for dealing with the goose population.
None of this is set, and to finish the grant, the group must finalize their report on findings and recommendations, and it is intended to apply for another 319 grant to help fund a management plan to maintain and improve the quality of Lake Leatherwood.
Dudley and the group spoke on moving forward with presenting findings to the Parks Commission and public with a draft report, though no date was set, with the idea of receiving public input on how the department might move forward.