Middle Fork Salt River Wetland & Stream Mitigation Bank

Project Location: The Bank is located in the southeast quarter of Section 22 of Township 56 North, Range 13 West with its approximate center at latitude 39.637842, longitude -92.334191. As shown in the attached maps, the proposed Bank is located approximately 10 miles southeast of Macon, Missouri.

Bank Objectives:
A. The goals of this proposed Bank are: 1) to provide appropriate compensatory mitigation for authorized impacts to jurisdictional aquatic habitats such as streams and wetlands within the
service area and, 2) to create water quality and wildlife habitat benefits to that service area through increasing the quantity and/or quality of in-stream, riparian, wetland, and wetland buffer habitats. To achieve these goals, the Sponsor proposes to undertake the following specific objectives:

• 32.46 acres of Riparian Buffer Restoration
• 0.57 acre of Riparian Buffer Enhancement
• 20.65 acres of Riparian Buffer Preservation
• 25.01 acres of Forested Wetlands Restoration
• 4.19 acres of Forested Wetlands Enhancement
• 0.22 acre of Emergent Wetland Enhancement
• 15.16 acres of Upland Buffers Restoration

• Provide stream bed stability through the installation of grade control structures in the Middle Fork Salt River and Intermittent #1, #2, #3, and #4
• Restore structural complexity on Intermittent #3 and Intermittent #4 by utilizing low-tech process-based stream restoration methods.
• Address stream bank and riparian instability and erosion by filling in and stabilizing the developing cutoff channel originating from Middle Fork Salt River and bisecting the Bank

B. The planting of native herbaceous and woody species and the removal of invasive species, such as reed canary grass (Phalaris arundinacea) which is present in small amounts on the Bank,
will restore impaired habitats and result in a net increase in the aquatic and upland habitat quantity and quality on the site. Moreover, riparian buffer restoration will reduce aquatic impairment from excess runoff and sedimentation.

C. The Bank land will then be legally protected as natural habitat in perpetuity using a conservation easement. The aquatic resources provided by the planned mitigation activities will address the loss of wetland and stream habitats within the Bank’s service area as compensatory mitigation for impacts to jurisdictional waters, including wetlands, authorized under Section 404 and Section 401 of the Clean Water Act and/or under Section 10 of the Rivers and Harbors Act of 1899. The proposed mitigation activities will improve water quality by increasing the amount of native riparian and wetland habitat on the site, filtering surface and subsurface water that drains across the Bank, and storing and treating water that floods the site when the Salt River overflows its banks.

Project Description/Bank Establishment:
A. The Bank has an advantageous landscape position low in the watershed of the Salt River and flooding has been frequent enough to prevent farming the site in some years. During pollutant-mobilizing flood events, some of the water carried by the Salt River and its tributaries will flow through the planted riparian buffers and wetlands. The lower velocity of flood flows through such areas will allow particles to settle out of the water and the interaction with plants and other organic material can remove sediment and other pollutants through physical-chemical interactions. This sediment removal would be advantageous as there is a Total Maximum Daily Load for sediment for 49 miles of the Salt River, including the portion within the Bank (Missouri Department of Natural Resources, 2006).

B. The most notable and unique long-term hydrologic process occurring on the Bank is the gradual formation of a cutoff channel between the easternmost bend in the Salt River on the
property and its bend just south of the southeastern corner of the Bank, south of Omega Street. During the multiple flood events that occur in most years, water from the Salt River flows into this cutoff channel, then through Intermittent #3 and Intermittent #4 and back into the Salt River. In the current condition, this cutoff channel is the greatest source of hydrology for the Bank but needs to be stabilized so that does not continue to erode to become the main channel of the Salt River which would cut off approximately 1.7 miles of the Salt River and drain many wetland areas on the Bank and in the floodplain areas along the stretch of the Salt River that would be abandoned. Over the long term, the incision on Intermittent #4 and head cut on Intermittent #3 threaten the stability of the high flow channel and need to be addressed.

C. To address the cutoff channel as both a hydrologic resource and source of concern, the design strategy is to stabilize the head cut and disperse the available hydrology across much of the
Bank to create widespread wetland conditions and increase the residence time of water on the Bank. This is proposed to be achieved by the construction of a berm and rock outlet structure that will control the water surface elevation and thus the depths of water in wetland pools and prevent the headcut in Intermittent #3 from migrating up the cutoff channel.

D. In addition to the high flow cutoff forming across the Bank, the river has already formed a cutoff channel along Omega Road immediately to the southwest of the Bank proposal. The
depressional nature of this portion of road has held water after storms for some time, but in recent years the road itself has become a perennial part of the channel. This sequence of events has resulted in the southern southwest corner of the Bank being a steep streambank that may need stabilization.

E. The planned compensatory mitigation activities on the Bank have been designed to address both the primary design objective of improving water quality and the secondary design objective of creating and enhancing natural habitats. The Bank will be seeded with native seed mixes and planted with native shrubs and trees selected for each habitat type and planted in densities sufficient to ensure the establishment of native plant communities. In addition, existing wooded areas on and in the immediate vicinity of the Bank will serve as a seed source for natural recruitment of colonizing species. The seed mixes, shrubs, and trees will be selected to increase diversity, advance the successional state of the plant communities on the Bank, and provide soft and hard mast for wildlife. Invasive and undesirable plant species will be eradicated by herbicide treatment or physical removal.

F. The number of wetland credits generated by the Site’s mitigation actions has been determined using the Missouri Wetland Mitigation Method (U.S. Army Corps of Engineers, 2017). As shown in the Bank Development Plan figures, the wetland mitigation activities that would generate these credits include the restoration and enhancement of emergent and forested wetlands and their associated upland buffers.

G. The Sponsor is proposing a variety of mitigation actions to improve the ecological state of the on-site streams. The Site’s stream mitigation actions are shown in the Bank Development Plan figures. The total number of stream credits generated by the Bank’s mitigation actions was determined by using the In-Stream and Riparian Buffer worksheets from the State of Missouri
Stream Mitigation Method (MSMM).

Total Stream Credits Generated (In-Stream + Riparian Buffer) = 52,308.84

Service Area: The proposed service area of the Bank consists of the portions of the Central Plains / Cuivre / Salt Ecological Drainage Unit (EDU) and the Central Plains / Des Moines EDU
located within Missouri. This service area comprises the watersheds within the State of Missouri that drain into the Mississippi River north of the Missouri River watershed along with the adjacent immediate drainage area of the Des Moines River (the Central Plains / Des Moines EDU). The Central Plains / Des Moines EDU is included in this service area because it is similar ecologically to the Central Plains / Cuivre / Salt EDU and only contains approximately one eighth of Clark County, which the Sponsor noted may be too small to support its own centralized mitigation service area.

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