The primary goal of the Project is to restore 441.35 acres of meadow floodplain function by eliminating gullied (incised) channels and re-establishing the channel-floodplain connection. The Project includes a variety of treatment techniques to eliminate channel incision, including partial fill in the 3 primary gullies (and several upland ditch fingers tributary to the primary gullies), and complete fill or riffle augmentation with rock and sod riffles in less-incised reaches of channel. On-site fill will be generated from in-gully borrow areas, creating ponds as the groundwater table recovers. Additional fill will be generated from a terrace on the meadow edge that will be graded, reducing the overall number of borrow ponds.
Filling the incised gullies at Mountain Meadows Creek would require excavation and placement, using heavy equipment, of approximately 80,000 cubic yards of soil in the 41 partial channel fill plugs, four upland ditch plugs, and one complete fill reach to eliminate the existing gullied channel and raise/restore the base elevation of surface water flow in the meadow. An additional estimated 125,000 cubic yards of fill would be placed in the upland, eroded segments of channel outside of mapped wetland areas, for a total of approximately 225,000 cubic yards of fill. At two key locations, fills will redirect stream flows into re-activated channels on the meadow surface, distributing flow across the floodplain. Stream flows will be redirected into non-incised channels on the meadow surface, distributing flow across the floodplain. Additionally, the project includes filling, abandoning, and seeding an eroded, cross-meadow roadway, planting/fencing of up to 300 native shrubs in the riparian corridor, addition of rock to an existing forest road to reduce erosion and accommodate sheet flow under restored flow conditions, removal of encroaching conifers on approximately 75 acres of meadow/riparian corridor, and construction of cross-pasture fencing to implement grazing management changes that promote habitat quality in the meadow.
The Project is expected to provide the following benefits:
• Benefit water supply and quality: The project will enhance groundwater retention, resulting in greater summer base flows and outflow extended later in the season. Water quality will be enhanced by eliminating bank erosion, while more vigorous meadow vegetation will filter floodplain flows.
• Improve plant communities and habitat: The project will increase total riverine habitat by reactivating the historic network of flowpaths on the meadow surface.Total length of channels in the meadow will increase from 23,596 linear ft to 28,391 linear ft. The subsurface hydrology to sustain wet meadow plant species will expand, increasing wet meadow acreage from 160 acres to an estimated 247 acres, and shifting an additional 120 acres of xeric grassland to more mesic meadow conditions. Habitat quality is also expected to improve in the riparian corridor through removal of encroaching conifers, allowing more sunlight for shade-intolerant riparian species.
Revegetation efforts will include seeding with native meadow graminoids and forbs and planting native riparian shrubs in the riparian corridor, expanding food sources for meadow birds. Increased wet meadow acreage and a greater diversity of forage species will accelerate improvements in avian species diversity, particularly for meadow focal species. Special-status species known to use the meadow include greater sandhill crane and gray wolf. Improvements in habitat quality will increase foraging opportunities for both species. See Appendix B, Wildlife Biological Assessment and Evaluation, for a complete description of potential effects and benefits to wildlife.
• Improve watershed health: Removal of encroaching conifers is planned within the meadow, in addition to post-fire fuel removal from 2,948 acres of the surrounding uplands in a companion forestry project. Dead and dying trees will be removed, and reforestation actions will be taken in high-severity burn areas. Forest treatments will reduce the risk of future catastrophic fires, thereby protecting water quality.