Groundwater and Surface-Water Monitoring in the Mill Creek Watershed, Wellfleet and Truro, Massachusetts

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The Herring River estuary and salt marsh system, within the Cape Cod National Seashore in Wellfleet, Massachusetts, has been diked off from the ocean for more than 100 years. The National Park Service is now preparing to restore the 1,100 acre estuary-marsh system.  

Estuary restoration will consist of installing a new tide gate to restore tidal flushing to large parts of the former salt marsh. The effort to restore the marsh is driven mainly by the expected improvements in coastal habitat, ecosystem services, and water quality resulting from increased tidal exchange. Restoration is expected to improve water and soil quality, increase river herring and shellfish habitat, reduce the extent of invasive plant species, and provide improved recreational opportunities.

Diking of the Herring River in 1909 allowed for the development of low-lying areas in the adjacent Mill Creek watershed, including portions of an adjacent golf course. Despite the drainage that occurred in response to diking, groundwater levels remain high in the Mill Creek flood plain, and low-lying areas are susceptible to surface inundation during high groundwater stages and precipitation events. The USGS, in collaboration with the Friends of Herring River (FHR), have established a groundwater and surface-water monitoring program in the Mill Creek watershed. The specific objectives of the project are to:

  • Determine water-table conditions and stream-aquifer interaction during the pre-restoration period and potentially during implementation of the Herring River restoration project.
  • Acquire additional subsurface lithologic and aquifer-property data to better define the hydrogeologic framework of the area.
  • Document the monitoring network drilling procedures, observation well and gage locations, construction details, measurement methods, and subsurface geologic data in a USGS Open-File Report.  Enter all water-level data into the USGS National Water Information System (NWIS).