Current River Conditions

Natural and Social History

Photo Galleries

List of Native Plants and Animals

Bronx River Stories

Histories

Gators in the Bronx!

The Old Snuff Mill

Jumpin' Jupiter!

The Mile Square

What's an Alewife, Anyway?

Water for Concrete

Paddling Back in the Day

1895 Tragedy in a Bronx River Swimming Hole

William Hart, the Bronx River Cowboy

Cowboys on the Bronx

Brittannia Rule the Bronx

The Old Drovers Inn

Look Out for the Little People!

Happy Birthday Bronx River Alliance

The Witch Canoe

Woodlawn Brook

The Mighty Kensico

The Battle of White Plains

Launching the Golden Ball

The Left Bank of the Bronx

Awaiting the Alewife

The Boltons of Bronxdale

Ann Hanson, the Bronx River Stevedore

Aunt Sarah Held the Bridge

Jerry, the Bronx River Sea Lion

How the Bronx Got Its Name

Lloyd Ultan's History of the Bronx River

The Wishing Rock

When Dinosaurs Ruled the Bronx?

Big Brown Joe Plugs the Pipe

Ungrateful Old Scrooge

Jonas the Peacemaker

Beaver Tales

Why the Beaver?

Bronx River Parkway Reservation

The Pudding Rock

The Rocking Stone

Edgar Allan Poe and the Bronx River

Shipbuilding on the Bronx

The First Canoes on the Bronx

There Were Bears in There

McAdam's Bronx River Driveway

The Mid-Bronx Ride of Paul Revere

The Many Names of Van Nest

The Frozen Water Trade

Colonel Burr Burns the Blockhouse

Beavers on the Bronx

Songs

Greenway Stories

River Restoration Stories

Video

The Mighty Kensico

Spanning the northern end of the Bronx River valley, the 307 foot-high Kensico Dam is a spectacular sight for walkers and bicyclists finishing a trip up the Bronx River Parkway Reservation. Behind it, the original sources of the Bronx River now lie beneath the waters of the Kensico Reservoir.

Together with the Ashokan Dam in the Catskills, the Kensico can share the title of the “last of the handmade dams.” Built to a classic design and covered with a quarried granite facing, it represents one of the final dams of its generation. The Kensico’s one million cubic feet of masonry is enough to build an Egyptian pyramid.

With its conventional straight wall, the Kensico is what engineers term a “gravity dam,” because it derives its stability from its sheer weight. The granite blocks covering its face are more than decorative; they lend essential weight to a structure holding back the 30 billion gallons of water in the Kensico Reservoir.

Six years after the Kensico was completed in 1915, the Swiss engineer Fred Noetzli proposed a design for an “arch support” dam, which by bending inward against the weight of the water would transfer some of the stress onto the anchorages at either side of the dam. This meant that less material would be needed to construct such a dam, making it cheaper to build, and with a greater margin of safety.

While engineers tested and refined Noetzli’s arched dam design in the mid-1920s, the development of poured concrete technology also proceeded apace, with the result that the next generation of high dams in the 1930s would be arched, concrete dams, leaving the once-celebrated Kensico looking like the last of its kind. Curiously, though, while the new arched support dams were hailed as a triumphant innovation, the humble beaver had been harnessing its principles for thousands of years: nearly every beaver dam is built with a slight inward arch.

Stephen Paul DeVillo