Posted on February 22, 2023
The General Edgar Jadwin Dam, one of two major structures protecting Honesdale, Hawley and other communities along the Lackawaxen from flooding, is getting updated for the first time since its construction more than six decades ago.
Ed Voigt, the government affairs officer for the U.S. Army Corps of Engineers (USACE) Philadelphia District, said that the project has run smoothly since it began in 2022, and it should be wrapped up by spring of this year. Residents who frequently hike along Dyberry Creek and near the base of the dam will notice little difference from how it looked before, he said. What will be different, however, is the level of safety it can provide.
The corps, which first began construction on the dam in 1957, completed a multiyear safety modification study of the structure in 2016, and found that a portion of the dam was originally built insufficiently, and could have potentially allowed water to seep through from one side to the other during a significant flooding event.
USACE awarded a near-$5 million contract last March to Mohawk Valley Materials of Marcy, NY to install a 400-foot-wide geosynthetic liner on the dam’s upstream slope to block potential seepage. Because of legislation regarding the year when the dam was built, this project is monetized completely by federal funds, according to Voigt.
After removing the riprap—which basically translates to “big rocks” placed on dams to combat erosion—the team got to work laying down several different layers of soil and various “geosynthetic” materials to make the dam practically “impermeable.”
“Nothing’s getting through it,” Voigt said. “It doesn’t erode; it’ll outlive all of us.”
Mostly all that’s left to do, he said, is for the team to replace the existing riprap back on top of the new layer of protection.
The Jadwin Dam sits three miles upstream from the confluence of Dyberry Creek and the Lackawaxen River. On a normal day, the dam maintains no pool of water; the water flowing from Dyberry Creek is directed through an outlet tunnel. For that reason, Jadwin is considered a “dry” dam.
During a flood, however, when the creek starts to rise and pooling does occur, the dam provides 24,500 acre-feet of storage before water reaches the spillway crest—the part of a dam, off to the side, that allows for the safe passage of excess water—and a total of 47,300 acre-feet of storage before the rising water crests the top of the dam.
“You don’t want water going over the top of the dam. That’s not a good day,” Voigt said.
Fortunately for residents downstream, Dyberry Creek has never even come close to overpowering Jadwin. Even during a three-year stretch of bad flooding seasons, concluding with the worst of the three in summer 2006, the highest the water ever rose was an elevation of 1,040 feet, about 12 feet below the spillway crest.
According to USACE, the Jadwin Dam has prevented approximately $46 million in potential flooding-related property damages since 1960. Its cousin, the Prompton Dam on Prompton Lake, has prevented a reported $36 million.
A flood event that’s bad enough to overtake Jadwin or Prompton is exceedingly rare. However, that doesn’t mean that residents along the creek and the river never have to worry about flood damage—as likely any long-time resident can attest. Properties that were built on the floodplain after the dam’s construction are at an increased risk, according to USACE.
Honesdale Borough, which deals with stormwater runoff issues practically every year, has created a dedicated stormwater committee in an effort to combat the issue. Closed roads and declarations of emergencies are common fare in the county during the rainy summer months. And some residents in particularly flood-prone areas have created Facebook groups to keep track of and commiserate over the flooding they’ve experienced in their backyards.
As the River Reporter has reported previously, the effects of climate change have already put the area at an increased risk of flooding. According to RiskFactor.com, there are more than 4,500 properties—10 percent of all properties—in Wayne County that have a 26 percent chance—or greater—of being severely affected by flooding over the next 30 years.
The corps, along with FEMA, strongly recommend that residents who live in an area with a high risk of flooding plan and discuss safety procedures during an emergency with other members of the household, and stay informed about their community’s evacuation routes.
For more information, the USACE recommends that residents read FEMA’s safety guidelines, which can be found in the agency’s online document by searching for “FEMA: Living with Dam.”
