DESCRIPTION: This study examined the feasibility of flood risk management alternatives to address flooding issues within the Township of Denville. Denville is a municipality located within Morris County, New Jersey which is approximately 25 miles northwest of Newark. The study is focused on the central part of Denville, which is subject to fluvial flooding from the Rockaway River and Den Brook. Township residents and businesses have suffered extensive losses and damage from multiple flooding events in recent decades, including Hurricane Irene in August 2011 and Tropical Strom Ida in September 2021. An integrated feasibility report and environmental assessment has been completed to document the analysis and conclusions of the study.
AUTHORIZATION: This study was conducted under Section 205 of the Continuing Authorities Program (CAP), which does not require individual study authorization.
STATUS: As a part of this study, which is an iterative process, the Project Delivery Team (PDT) analyzed several different flood risk management alternatives. Throughout the process the PDT coordinated their work with the New Jersey Department of Environmental Protection (NJDEP), the non-Federal sponsor, and the Township of Denville, the local stakeholder on the project. Studied alternatives included various structural measures such as floodwalls with closure gates, floodwalls in combination with road raisings, and diversion culverts. None of these structural alternatives analyzed were found to be economically justified so they were not moved forward.
In addition to the structural alternatives the PDT also analyzed nonstructural measures such as elevations, wet floodproofing, and dry floodproofing. The nonstructural analysis conducted by the PDT identified multiple groups, or clusters, of structures within the study area that were economically justified which indicated that the benefits outweighed the costs.
In September 2025, the Baltimore District completed the integrated feasibility report and environmental assessment and furnished it to New York District. In early October 2025, the NY District routed the report and accompanying recommended plan to the North Atlantic Division Commander, Colonel Jesse T. Curry.
The recommended plan calls for non-structural measures including elevation, wet floodproofing, and dry floodproofing, on 18 residential and 7 non-residential properties located in two clusters, Southwest and North Riverside Drive. The anticipated cost for the design and construction of these measures is $19.5M.
Next Steps: After the recommended plan is endorsed by the NAD Commander, the design and implementation phase will begin with the execution of a Project Partnership Agreement (PPA) between USACE and the non-Federal sponsor, the New Jersey Department of Environmental Protection. Once the PPA is executed, property owners who want to voluntarily participate in the project can be identified, and from there work can begin on designing and implementation the flood protection measures. Construction is anticipated to take three years, depending on local cooperation.
CONTACT:
Evan Nelson
Project Manager
P: (917) 790-8350
Email: evan.m.nelson@usace.army.mil
U.S. Army Corps of Engineers, New York District
26 Federal Plaza
New York, NY 10278
CONGRESSIONAL DISTRICTS:
NJ-11