Schoharie County Soil and Water Conservation District (SWCD) And New York City Dept. of Environmental Protection (DEP) Replace undersized culvert to Schoharie Reservoir

Through their Stream Management Implementation Program (SMIP), DEP funded replacement of an undersized round culvert in the Town of Gilboa. Schoharie County SWCD and DPW identified a serious problem with a culvert on South Gilboa Road in the Town of Gilboa. An application was submitted to the Schoharie Watershed Advisory Committee (SWAC) to procure funding to remedy this issue. The project would remediate a water quality and flooding issue in a direct tributary of the Schoharie Reservoir.

This direct drainage to the Schoharie/Mohawk Watershedinvolves 2 streams. One has a small drainage area, less than a ½ mile, but the other has a drainage area of 1.5sqmi. During high flows the larger stream would jump out-of-bank, run down S. Gilboa Road and cause a 3 fold increasein the amount of water getting into the smaller stream. In response to the excess flows,the small stream had severely incised destabilizing banks sending sediment into the system. The excess water also caused extensive damage to S. Gilboa Rd.

5’ project culvert before replacement where the upper stream would flank the project culvert due to a bad angle leading to over-topping and water flowing down S. Gilboa Rd

Prior to culvert replacement a Geomorphic studyalso funded by DEP showed that the 5’ culvert would only be able to convey flows less than a statistical 5 year event, and that larger events would be forced over the culvert and onto the roadway. Mitigating this problem required increasing the culvert size to a 5’ x 17’ boxed culvert. The design also called for some channel grading above and below the new culvert, bank stabilization, and plantings to complete the project. The project was completed in August of 2016 so the road could be reopened before school started. The Schoharie County DPW, users of S. GilboaRoad and homeowners living along the roadway are very appreciative of this project.

New culvert under S. Gilboa Rd. Note natural material in culvert bottom