Disastrous Dam Failure in Connecticut Eleven People Killed


“The most terrible disaster that has ever occurred in Danbury happened last night, destroying a number of lives and much property,” reported the New York Times.

The Kohanza Reservoir released its icy waters killing eleven people within the first half hour at 7:00 pm on January 31, 1869. A deluge of water carrying rocks, trees and large ice floes burst through the town of Danbury, Connecticut taking with it houses, businesses and demolishing three bridges entirely.

Danbury, CT History

Eight families first settled in the area nicknamed Swampfield as early as 1685. The first hat factory was established in 1780, and by 1860, the Danbury museum reports that there were 12 hat factories employing upwards of 2,000 hatters. The community of Danbury quickly grew to over 7,000 residents by 1860, and close to 9,000 by 1870.

The Lower Kohanza earth fill Dam was built by the residents in 1860. This earthen dam was 336 feet (102 m) long by 27 feet (8.2 m) in width. The reservoir created contained 40 million gallons of water. In 1860 residents built their water lines out of wrought iron, wood, and cement to supply the town of Danbury with water from the reservoir located 3 miles (4.8 km) away.

The Hatting Capital of the World

The hatting industry rendered beaver fur into felt by boiling it down with water and mercury. The felt could then be shaped into hat forms. The hatting industry waste, along with the town’s waste followed the newly constructed sewage system into the Still River. City historian, Bill Devlin reported that acids, dyes, fur wastes along with the city’s waste created typhoid and cholera epidemics.

At this time about 1.5 million hats were created each year. Soon Danbury would be nicknamed The Hat City or The Hatting Capital of the World.

Danbury was growing exponentially. The rail lines were bringing in coal to fuel the factories and homes. by 1865, the residents of Danbury realized they needed more clear water. The Upper Kohanza earthen dam was constructed.

Flood Disaster

It was Sunday evening about 7 o’clock January 31, 1869 that the upper Kohanza dam let go, carrying with it in the flood surge the lower Kohanza dam as well. The water held in the two reservoirs flowed with such a force, that the newly repaired Flint’s dam was also destroyed. Three bridges in town were destroyed and carried downstream.

Flash Flood

Ice floes, rocks, trees carried in the torrent of water swept away houses, bridges, and buildings in a matter of minutes. Initially only five of the bodies were found downstream trapped in ditches of the eleven residents who were killed.

The city of Danbury, Connecticut now boasting a population of 79,743 still employs eight reservoirs, some of these still historical earthen dams which are subject to annual inspection. During the height of the hatting industry the city relied upon about 7 million gallons of water a day about the same water usage as the present population.

It was in 1895, following a number of law suits that the city of Danbury finally built a filtration plant to stop polluting lands down steam.