gasconade river wetland and Stream mitigation Bank

Gasconade County, Missouri

The 138-acre Gasconade River Wetland and Stream Mitigation Bank provides compensatory mitigation for impacts to wetlands and streams throughout the Gasconade River watershed in central Missouri.  This unique site consists of a broad, low-lying valley surrounded by a crescent-shaped steep Ozark hillside.  The agricultural conversion and crop production on the property involved the clearing of all of the natural vegetation in the Bank’s valley, straightening the onsite stream, preventing the regrowth of a meaningful riparian buffer, draining much of the Bank, and logging the forested hillside.

The shallow local topography and poorly drained soils presented an opportunity to spread the water carried by the stream across a wide area through the construction of berms designed to emulate the long flat beaver dams that would historically have made similar small ponds and wetlands in flat tributary valleys such as the one that occurs in the Bank.  Additional earthwork imitated the morphology of two stream terraces and created more wetlands with significant microtopography.  Stream habitat was also improved by removing a piped farm crossing that was preventing natural flow patterns.

This site contains approximately 8 acres of created riparian corridor and almost 34 acres of wetlands surrounded by about 95 acres of upland prairie and forest buffers.  In addition, the bank surrounds a 16.5-acre permittee-responsible mitigation site which contains notably high botanical and wetland habitat diversity.  The herbaceous layer in parts of the restoration areas had a high level of diversity, but the tree layer contained only a handful of species.  Additional herbaceous species have been planted and numerous tree and shrub species have been introduced to the site to drastically enhance the wooded diversity. In addition, some areas in fallow fields surrounding the low-lying area have been excavated and planted with the same diverse mixture of appropriate native wetland species.

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Recently, the Gasconade River Wetland and Stream Mitigation Bank was independently verified by the Missouri Herpetological Association to sustain habitat for small-mouthed salamanders (Ambystoma texanum) and marbled salamanders (Ambystoma opacum). Small-mouthed salamanders had not been previously observed in Gasconade County and marbled salamanders had not been recorded in the county in more than 30 years. Several central newts (Notophthalmus viridescens louisianensis) have also been observed at this location. The presence of these salamanders shows that the mixture of high quality habitats at this mitigation site is providing valuable wildlife habitat for species that need both upland and wetland ecosystems to survive and reproduce.