Essex Exec Opposes South Mountain Reservation Dam

Submitted by the Office of the Essex County Executive:

Essex County Executive Joseph N. DiVincenzo, Jr. announced that he does not support a proposal to build an 880-foot long, 70-foot tall earthen dam in Essex County South Mountain Reservation and asked the Army Corps of Engineers to look into other strategies to address flooding downstream on the Rahway River. If constructed, the dam would transform a large part of South Mountain Reservation into a “retention basin” for flood waters after heavy storms, close Brookside Drive and create a structure that would tower over any nearby buildings.

“The potential for flooding in Millburn, Cranford and other communities downstream the Rahway River is a serious issue and should be addressed. However, it can’t come at the expense of destroying an natural resource such as South Mountain Reservation and reducing the quality of life for Essex County residents,” DiVincenzo said. “We have always maintained that protecting the reservation was our priority and informed the Mayor’s Council on the Rahway River in the summer of 2013 of this important and unchangeable condition. We also told them to find alternatives that were less detrimental to South Mountain and kept Brookside Drive open."

DiVincenzo pointed out that a similar proposal to develop a dam and create a detention basin was introduced in the late 1970s and early 1980s. At that earlier time it was concluded that the plan would have detrimental effects on the reservation and would not significantly address the issue of flooding downstream.

A study in 1976 led by Thomas C. Hunter, Jr., Colonel and District Engineer with the Army Corps of Engineers, states there are other ways to address the flooding issue, including deepening the Rahway River so more water can be held between its banks, stabilizing the Rahway River by constructing concrete channels, and creating floodwalls and levees in the vicinity of Millburn, and widening and deepening the river channel, modernizing bridges to allow flood water to flow through unimpeded, and using some concrete channels in the vicinity of Cranford. The study also found that the costs of using Diamond Mill Pond and Campbell’s Pond in South Mountain Reservation “far exceed the flood control benefits derived from such a plan” and that Campbell’s Pond has been “found to be marginally uneconomical” and “would have little effect upon the flood problem experienced along the East Branch in the Townships of Millburn and Union.”

In addition, an environmental assessment of the plans from 30 years ago concluded that creating the detention basin would be detrimental to transportation, recreation, the local economy, land usage and breed mosquitoes.

• Transportation: “Roads would still be inundated and the traffic problems would still occur.”
• Recreation: “Since these areas are usually not protected by a non-structural solution, flooding would result in an adverse effect on certain forms of recreational use.”
• Economy: “Land that is still continuously flooded would have a detrimental effect on monetary values of this property. Additionally, the relocation of structures would affect the tax base of the affected locality.”
• Land Usage: “Flooding would preclude the utilization of the remaining unprotected land for residential, commercial, industrial or recreational purposes.”
• Mosquitoes: “Poor drainage and stagnant pools following recent flood episodes would provide additional breeding grounds for mosquitoes.”
  

It concluded that building a dam to create a detention basin in the area of Campbell’s Pond would not completely eliminate flooding and that “during flooding episodes, vegetation, animals and aquatic life would be periodically disrupted or destroyed within the detention basin itself. It was, therefore, concluded that the benefit of no work along the West Branch in Millburn resulting from a detention basin was outweighed by the potential environmental damage to the 63 acre area surrounding Campbell’s Pond.” 

Carl Moritz, former Essex County Director of Parks, Recreation and Cultural Affairs Director, authored an inter-office correspondence in 1979 that quantified the negative impact a dam and detention basin would have on South Mountain Reservation. According to Moritz, because of the periodic flooding, 286 acres of woodlands, more than five miles of hiking trails, a campsite, two picnic locations, three scenic lookout sites, and roads for motor vehicle traffic would be lost.