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Cost-share monies are available for the following options:
1. Additional 25% cost-share funds will be offered for those projects funded through USDA's Environmental Quality Incentives Program (EQIP).
2. Practices include: Water & Sediment Control Basins, Terraces, Diversions and Grade Control Structures.
Water and Sediment Control Basins: are earthen embankments constructed across depressional areas of concentrated runoff. They perform a function very similar to that of terraces. Drainage areas controlled by these structures should be less than 50 acres so in many cases, a series of basins is needed to properly control erosion and to be compatible with farm machinery.
This practice is very effective at preventing gully erosion, trapping sediment, and reducing downstream peak flows. The practice can reduce suspended solids and runoff by 40 to 60% according to a MPCA publication Agriculture and Water Quality: Best Management Practices for Minnesota. However, they are not effective at removing soluble pollutants.
Terraces: a earthen embankment that is constructed across a slope to intercept runoff. Terraces are best suited to uniform, gently to moderately sloping fields (2% to 12% slopes) that have erosion problems. There are two basic types of terraces. Storage terraces collect water and store it until it can infiltrate into the ground or be released through a stable outlet. Gradient terraces are designed as a channel to slow runoff water and carry it to a stable outlet like a grassed waterway.
Properly designed, installed, and maintained terraces can be very effective at reducing erosion and trapping sediment and nutrients. Studies in Iowa of storage terraces show reductions of 95% for sediment, 84% for soluble nitrogen, 93% for attached nitrogen, and 73% for soluble phosphorus, and 93% for attached phosphorus according the MPCA publication Agriculture and Water Quality: Best Management Practices for Minnesota. Gradient terraces provide less infiltration, and consequently fewer benefits.
Terraces are not recommended on fields with very stony, steep, or shallow soils, nor are they recommended on fields with irregular topography and short slopes. They are also relatively expensive to install, and require a substantial amount of time to design and construct.
Diversions:an earthen channel constructed across a slope to collect water and prevent damage to an area below. Diversions act much like a terrace, but their purpose is to direct or divert runoff water from an area. A diversion is often built at the base of a slope to divert runoff away from bottomlands. These structures may also be used to divert runoff from a feedlot or to collect and direct water to a pond. In cropland, diversions can be effective in reducing soil erosion by 30 to 60% according to the MPCA publication Agriculture and Water Quality: Best Management Practices for Minnesota.
Grade Control Structures: these structures involve pipe outlets or drop spillways and are used to allow water to drop to a lower elevation while protecting the soil from gully erosion or scouring. While they are expensive to design and construct, grade control structures can be a necessary component of an overall management plan. They are often used at the outlet of a grassed waterway to stabilize the waterway outlet.
Sediment originating from unstable areas can be reduced from 75 to 90% with grade control structures according to the MPCA publication Agriculture and Water Quality: Best Management Practices for Minnesota, but are only effective for localized erosion control.
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