How the Mt. Morris Dam Saves Rochester

by Chris Clemens

Letchworth State Park receives hundreds of thousands of visitors each year from around the globe. Known as the “Grand Canyon of the East”, the gorge was naturally created by the north-flowing Genesee River. The formation is easily one of the most beautiful natural sites in New York. But, that same gorge once caused regular flooding in the city of Rochester, some 30 miles to the north. The views at Letchworth are as about picturesque as you can get, but the man-made Mt. Morris Dam in Letchworth is nearly as magnificent. The colossal concrete spillway keeps its neighbors to the north from having to pump itself out of regular floods.

And, you can take a dam tour for free!

Flooding in Rochester

Between 1865 and 1950, every seven years or so the mighty Genesee River would deliver water levels that became overwhelming for Rochester. Since the river cuts directly through the city center, there were some years when flooding devastated the surrounding blocks. Efforts were made in downtown to control the heavy flows of water, but the channel still regularly had problems after spring thaws.

In March 1913, after a major snow had melted, much of the northeast waterways in the United States swelled. The monumental flood inspired a bunch of programs across the state, including the man-made Great Sacandaga Lake at the foot of the Adirondacks. Here in Rochester, the high water levels caused immeasurable damage in the blocks around the Genesee. As you can see from this photo of Front Street, even the famous Zweigle’s had trouble!

Army Corps of Engineers to the Rescue

In December 1944, President Franklin D. Roosevelt signed a bill created by Congress called the Flood Control Act. It was a country wide effort that gave birth to a series of dams and river basin projects. Part of the Flood Control Act of 1944 earmarked $25 million dollars to build a dam in Letchworth on the Genesee River. Ultimately, this new dam would keep Rochester from being under water every few years.




The Buffalo office of the United States Army Corps of Engineers (USACE) was charged with building what would soon be known as the Mt. Morris Dam in Letchworth. After careful planning and research, they started the project in 1948.

Once completed in 1952, the monument was the largest concrete dam east of the Mississippi River. It stands 245 feet tall, and stretches 1,028 feet across the gorge. To achieve that, they lowered 750,000 cubic feet of concrete in huge buckets to build 11 individual monoliths containing nine gates that let water through. A six-story tower allows engineers and staff to maintain the structure, but even today the U.S. Army Corps office in Buffalo is watching from afar.

Leaving Us Low and Dry

Since the Mt. Morris Dam was completed in 1952, the USACE estimates that a total of $1 billion worth of damage has been prevented. Much of that was saved just in the year 1972, when Hurricane Agnes ravaged the country after moving north from its origin in the Yucatan Penninsula. Even though Agnes didn’t technically hit New York, the waters it left definitely did.

That year the Genesee River reached heights that is only expected every 300 years. Had the Mt. Morris Dam not been completed just a couple decades before, it’s believed that $210 million in damage would’ve been caused in Rochester. While we’ve certainly had damages in the region because of flooding, it would be way, way worse if they hadn’t spent $25 million to build this dam in Letchworth.

For a bunch of great photos from that year at the dam, checkout the Flood of ’72 page on Letchworth Park History.

It’s Dam Big

Today, you can visit and get a fantastic view of the gorge and the entire structure. But, for those really wanting an experience, they offer free walking tours right inside the dam a few times a week!

Just south of the village of Mt. Morris, you’ll find a couple access roads to the William B. Hoyt II Visitor Center in the Mt. Morris Dam and Recreation Area. The Visitor Center has some great historical exhibits with panels and photos from previous floods. There’s also a short video to watch, which is really informative.

You can register at the Visitor Center to join a free walking tour that descends down inside the dam. A USACE civilian guide leads tours to the top of the dam looking out over the river.

Then, the group goes inside and takes an elevator to a passageway and you get to walk around a bit inside. Photos are not allowed inside the dam, so I can’t really show you what to expect. But, try to imagine walking through a dimly lit cavernous tunnel surrounded by tons and tons of smoothed concrete. Occasionally you pass some gadgetry, but for the most part, it’s just smooth, concrete tunnels.




One of those tunnels leads to a small deck at the bottom of the dam just above the river. Tours go out on the deck, and visitors are allowed to look around and get a sense for truly how gargantuan the dam itself is.

Take a Dam Tour

You may have visited Letchworth State Park before, and maybe you’ve even visited the Mt. Morris Dam and Recreation Area before, but if you haven’t ever gone inside the dam itself, I strongly recommend taking a tour! To find times and visiting information, checkout the William B. Hoyt II Visitor Center website for more information.

Chris Clemens is the Founder/Publisher of Exploring Upstate. From his hometown in Rochester, he spends as much time as possible connecting with the history, culture, and places that make Upstate New York a land of discovery. Follow him on Twitter at @cpclemens