by David Hoyle

A Tide Mill Institute email subscriber recently asked TMI why historical tide mill sites are not being used to generate electricity. It’s a fair question: for an 8-foot tidal range, each acre of a tidal basin could power one typical household. The simple answer: the multiple hurdles to be overcome to implement tidal power generation seem to outweigh the benefits. In other words, there does not seem to be a need for tidal power compelling enough to motivate an individual, community, or developer to overcome those hurdles.

First, let’s remember that a historical tide mill required a dam to impound water at high tide and used the difference in head between the tidal basin and the sea to generate mechanical power. Producing electricity in this way is called tidal range generation. (Generating electricity by placing a tidal turbine in tidal currents, without a dam, is called tidal stream generation. While tidal stream generation was not common historically, it has become the de facto standard for new tidal electricity generation projects today.)

Obstacles for Tidal Range Power Generation

In cases where a historical tide mill dam has been transformed into or replaced by a causeway with culverts to permit limited water exchange, the former tidal basin has typically become a lake with little tidal amplitude. Property owners surrounding the lake would be understandably reluctant to support a power generation project that would transform their stable lake back into its original, tidal state, filling and emptying twice a day.

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How a possible 18th century tide mill site was recently discovered in Connecticut

“Gold is where you find it” was how prospectors responded when asked where to seek the precious metal during California’s 1849 Gold Rush. They were saying gold could be anywhere – but you had to look for it. The same could apply to finding old tide mill sites, and that’s the core message in a tide mill hunting lesson by Mark Borton, a seasoned discoverer of tide mills, independent historian, and author. Mark often travels from his home in Connecticut to Maine, Nova Scotia, and other places to investigate possible tide mill sites, but his latest find is a shorter drive: Old Saybrook, Conn.

It all started with general windmill research for another project, which revealed the existence of a 1636 windmill in Old Saybrook. He couldn’t resist going there to see a millstone from that windmill and visit the town’s historical society to search for more information about it. There he discovered that Old Saybrook has 10 historic mill sites, including two tide mills. One was at the Ox Pasture dam and the other at Oyster River bridge.

Continue reading “Tide Mills Are Where You Find Them” →

The National Hydropower Association’s Marine Energy Council has just refreshed their website with lots of current information on US marine energy developments that is likely to be of interest to Tide Mill Institute’s members. [Link]

Some of the more noteworthy items include:

• A carousel of photographs showing marine energy devices deployed in the water.
• Notes on marine energy’s strategic role in the US energy portfolio.
• An interactive map of the US highlighting the locations of marine energy suppliers, developers, labs and universities.
• Spotlights on marine energy developers.

Tide Mill Institute joined the National Hydropower Association, the trade association representing the US hydropower and marine energy industries, in 2023. David Hoyle represents TMI on the Marine Energy Council, and also participates in the MEC’s Priorities Working Group. In recent years, the Priorities group has surveyed marine energy developers and researchers to establish priorities for funding by the US Department of Energy; the priorities are explained in a position paper. In 2026, the PWG provided input to – and feedback on – the update of the NHA ’s Marine Energy website.

The International Molinological Society (TIMS) is still accepting registrations for its September 5th – 13th mill tour in Belgium. Day 4 of the tour includes a visit to the Spanish Mill of Rupelmonde, on the Scheldt River, about 30 miles southwest of Antwerp. The fully restored Spanish Mill, originally constructed in 1517, is the only working tide mill on the European continent, outside of the UK.

The seven-day tour visits 31 windmills, 13 watermills (including Rupelmonde), 2 horse mills, a farm mill, and a treadwheel used by a dog. Four museum collections and a miller’s statue are also included. Mill types include flour mills, oil mills, a flax mill, and a paper mill.

Detailed Program

Registration Information

Registration has opened for the 2026 tide mill conference being held in Fairfield, Conn., on Saturday, April 25. You can attend “Tide Mills of Long Island Sound” in person at the Fairfield Museum and History Center or on line via Zoom conferencing.

Long Island Sound has at least 24 identified historical tide mill sites on its shoreline and tidal inlets. This year’s conference focuses on selected sites on Long Island and the Connecticut coast. Join us for an outstanding slate of illustrated talks and discussions of tide mill history and tidal energy.

Continue reading “Register Now: April 25 Tide Mill Conference in Connecticut” →