A King Tide is the highest predicted ocean tide, occurring at new and full moons when the gravitational pull of both the sun and moon is at its highest. If you’ve heard of a spring tide or sunny day flooding, you’ve also heard of a King Tide.

I sat down with Gayle Bowness, Municipal Climate Action program manager and Abigail Long, resilience outreach fellow at the Gulf of Maine Research Institute, to discuss the coming King Tides and the flood risks they pose to our coastal community.

Significance of King Tides

On Dec. 23, a storm surge of approximately 2.4 feet occurred during a predicted high tide of 11.3 feet, resulting in a record setting storm tide of 13.7 feet. Dan King photo

Maine has a large tidal range, typically anywhere from 8 to 11 feet. King Tides in Casco Bay bring tides that exceed 11.5 feet, that can cause flooding and damage to our coastal ecosystems and shoreline infrastructure.

“When I started this work in 2016, King Tides were predicted once or twice during the spring and fall,” said Gayle, “In 2023, we’ll experience King Tides several times each month in the spring and fall high water season.”

So, why is this significant? Much of the city’s infrastructure and economic value are in its lowest lying, coastal areas prone to flooding. As sea levels rise, we also become more vulnerable to flooding from weather events – think summer tropical storms and winter nor’easters.

This was the case on Dec. 23, 2022, when a storm surge of approximately 2.4 feet occurred during a predicted high tide of 11.3 feet, resulting in a record setting storm tide of 13.7 feet. Flooding at this scale challenges the safety and accessibility of our resources and evacuation routes away from our coastlines.

“It’s not a matter of if, but when our coastlines will change,” Gayle said, “we have higher seas (as a result of climate change) and are seeing more severe storm systems, which inevitably means more flooding.”

Our city is deeply invested in improving our coastal resilience through projects, education and outreach and partnering with organizations like Gulf of Maine Research Institute to work toward solutions collaboratively. What we need most is your input to inform our planning and ultimately drive the policies and programs needed for these solutions.

Get involved

“By expanding individual’s awareness, we can help to escalate their sense of agency to directly address the actions they can make as a community,” said Abigail Long, resilience outreach fellow at the institute, “how much people feel in control of their own actions and responses results in better overall solutions. At Gulf of Maine Research Institute, we have ongoing programming that offers community members the opportunity to share local knowledge and contribute data to inform community resilience planning.”

Gulf of Maine Research Institute’s Coastal Flooding Community Science project invites you to visit coastal flood monitoring sites throughout the greater Portland area to make high water observations – take photos, note weather conditions, and provide input on flood impacts. City sustainability departments will use this data to support decision-making and adaptation plans.

The King Tides that we experience today are a window into the future as we’ll experience these tidal levels (and higher) more frequently. Check your local tide gauges at https://tidesandcurrents.noaa.gov/map/ and witness these tides yourself (and contribute to the Coastal Flooding Community Science project). You can also join Gulf of Maine Research Institute as it leads high-water walks during the events.

To learn more about the Coastal Flooding Community Science Project, visit: www.gmri.org/projects/coastal-flooding-community-science/.

To learn more and register as an observer in Gulf of Maine Research Institute’s Ecosystem Investigation Network, visit www.investigate.gmri.org.

To join Gulf of Maine Research Institute’s email list for notices about upcoming events, visit www.gmri.org/join-community/.

Our Sustainable City is a recurring column in the Sentry intended to provide residents with news and information about sustainability initiatives in South Portland. Follow the Sustainability Office on Instagram and Facebook @soposustainability.

Steve Genovese is a Greater Portland Council of Governmanets Resilience Corps fellow serving in the South Portland Sustainability Office on an 11-month term. He can be reached at sgenovese@southportland.org.