By: Julie LaBranche, Rockingham Planning Commission

The Rockingham Planning Commission (RPC) worked with the municipalities of Portsmouth, Rye, Hampton, and Seabrook, and the Department of Natural and Cultural Resources (DNCR) NH State Parks to design, coordinate, and implement a community-based High Water Mark (HWM) Initiative and identify local flood adaptation and resilience actions. The HWM project achieved four main goals:

  • Installed permanent markers and signage in strategic locations showing the elevation and causes of flooding from past and/or future events including future projected sea-level rise and storm surge.
  • Provided information on flooding and flood risks provided to large numbers of local residents and visitors from the Seacoast region.
  • Engaged municipal decision makers engaged in discussions about flood risks in their community and what their community is doing and can do to address those risks.
  • Prepared Case Stories about how the project participants are responding to flood risks and actions they’ve taken and intend to complete in the future.
  • Prepared a Climate Resilience Checklist and Guidance to aid municipalities and other climate adaptation and resilience practitioners with implementation.


Assessing Flood Risk in the Lamprey River Watershed

Many parts of NH’s coast experience seasonal flooding today and even larger areas may be impacted more frequently as sea level rises. Raising awareness about flooding is of interest to many municipal stakeholders, residents and businesses. High Water Mark signs have been installed to benchmark the 100-year coastal storm flood level and future projected sea levels at six locations across the Atlantic coast at the following locations:

  • Hampton Transfer Station off Hardardt’s Way near the front gate
  • Seabrook town boat launch on River Street
  • Seabrook at Brown’s Lobster Pound on Route 286
  • Rye at Wallis Road near the corner of Route 1A
  • Odiorne State Park at the boat launch area on Route 1A
  • Portsmouth at Strawbery Banke Museum’s Marcy Street parking area
<iframe src="" width="640" height="480"></iframe>

What can you do to spread the word about flooding? Take a photo with a High Water Mark sign and post it to social media using the hashtag #highwatermarknh. Follow RPC on Facebook at RockinghamPlanning and Twitter at @RPC_NH and watch for photos taken at the High Water markers using #highwatermarknh. Visit the HWM project website at

This project was funded, in part, by NOAA’s Office for Coastal Management under the Coastal Zone Management Act in conjunction with the NH Department of Environmental Services Coastal Program.