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For over 50 years, the NRCS has assisted in the construction of over 11,000 small watershed dams. These dams provide millions of dollars in benefits each year by providing flood control, wildlife habitat, recreation, irrigation and livestock water, and municipal and rural water supplies. While many of these dams continue to adequately provide these benefits, it is currently estimated that nearly half of the NRCS dams will surpass their planned service life in the next 10 years. For these structures to continue to function properly and safely, rehabilitation is required. If ignored, these dams could place life and property at risk.

The ARS Hydraulic Engineering Research Unit (HERU) has partnered throughout its existence with the NRCS by assisting them with their research needs in flood control related areas including vegetated spillways, principal spillway inlets (i.e. trash racks) and outlets (i.e. riprap protection in plunge pools), and grade control structures (i.e. rock chutes). As NRCS watershed structures reach the end of their planned service life, HERU continues to work on issues related to their safe operation. The objective of this paper is to provide information on current and future research conducted at the ARS Hydraulic Laboratory. Current projects at HERU include research of allowable overtopping and embankment erosion due to overtopping (i.e. vegetal failure, concentrated flow, headcut migration, and breach timing, formation, and widening) and RCC stepped spillway design (i.e. converging chutes, stilling basin design, various step heights for optimizing energy dissipation). This research is being conducted in order to give conservationists and engineers additional tools in rehabilitation design. concern.