Mitigation Management developed a compensatory mitigation restoration plan for the Jackson Farms Mitigation Site in accordance with the following regulatory guidance/rules:
- Guidelines to Establish and Operate In-Lieu Fee Programs in Georgia (USACE, 2011),
- Standard Operating Procedure, Compensatory Mitigation [March 2004] (“2004 SOP”),
- Compensatory Mitigation for Losses of Aquatic Resources [33 CFR Part 332, 73 FR 19594-19705, April 10, 2008] and [40 CFR Part 230] (“2008 Final Rule”).
The JFMS was approved to provide stream mitigation credits to offset impacts that had been previously authorized by the U.S. Army Corps of Engineers (USACE).
The JFMS is located in Mitchell County, Georgia, within the Ochlockonee River watershed. The site contains four unnamed tributaries to Big Creek. The site was historically used for agriculture and forestry practices. These practices greatly contributed to the degradation of the stream system by creating in-channel vertical and lateral instability and by introducing non-native species within the riparian buffer, thereby creating long-term instability and further demarcation from a state of natural quasi-equilibrium. The existing incised and entrenched channels created areas of extremely high in-channel shear stress. This in turn lead to further channel degradation as well as removal of natural and stable habitat for biological communities.
As part of the proposed JFMS, four streams and their riparian buffers were restored and protected. This proposed work provided significant reductions in sediment to Big Creek and allowed for the creation stable biological habitat. These goals were achieved by restoring ditched and channelized streams to their proper function through the creation of stable patterns, profiles, and dimensions; as well as, installation of habitat specific structures. Specifically, the JFMS increased bedform diversity, reduced sediment supply from streambank erosion, restored
floodplain connectivity, increased dissolved oxygen, increased macroinvertebrate diversity/abundance, and established a stable riparian buffer.
The goals of JFMS were achieved through these objectives:
- Increase bedform diversity
- Decrease pool-to-pool spacing (pool spacing ratio: 3.5-7 BKF widths)
- Increase large woody debris (>300 LWD index score)
- Reduce sediment supply from streambank erosion
- Reduce streambank erosion rates to reference conditions (BEHI index score < 19.5)
- Restore floodplain connectivity
- Reduce bank height ratios to 1.0 – 1.2
- Increase entrenchment ratios to greater than or equal to 3.0
- Establish and maintain a stable riparian buffer
- Manage invasive species within 100’ on each side of restored stream channel (<10% were non-native woody species at end of monitoring period)
- Restore mid-successional hardwood forest within 50’ on each side of restored stream channel (<10% were non-native woody species at end of monitoring period)
- Preserve late-successional hardwood forest 50’–100’ on each side of stream channel
Ultimately, the organization was responsible for implementing the final restoration plan. This plan included:
- Restoring approximately 9,878 LF of Priority 1/2 Stream Channel Development
- Installing 10 Constructed Riffle Structures
- Installing 78 Log Vanes
- Installing 43 Woody Debris Jams
- Installing 36 Woody Riffles
- Installing 51 Toe Wood Structures
- Installing 28 Log Step Structures
- Backfilling of old abandoned channels in their entirety
- Stockpiling topsoil and replacing on cut areas