Green Brook Upper Basin General Reevaluation Report

DESCRIPTION: The Green Brook Sub Basin is located within the Raritan River Basin in north-central New Jersey in the counties of Middlesex, Somerset and Union. It encompasses 13 municipalities and drains approximately 65 square miles of primarily urban and industrialized area. For the majority of the project area, the most damaging floods of record resulted from the August 2, 1973 storm, Tropical Storm Floyd on September 16, 1999 and April 15-17 2007 Nor’easter. Eight deaths were attributed to these floods. The Final General Reevaluation Report (GRR) and Supplemental Environmental Impact Statement (SEIS), dated May 1997 recommended flood protection for the Lower Basin and Stony Brook Basin, and is supported by the project sponsor, the New Jersey Department of Environmental Protection. Based on this report and input obtained during the public review period, the State of New Jersey requested that the upper portion of the project be deferred, pending additional consideration of alternatives.

The State of New Jersey has requested that a reevaluation of the deferred upper portion of the project be initiated. This effort will be accomplished in two phases.  Phase I will be the Validation study which is Construction General (CG) funded and is cost shared 75 percent Federal and 25 percent non-Federal.  Phase II will be the GRR which is General Investigations (GI) funded and is cost shared 50 percent Federal and 50 percent non-Federal. 

AUTHORIZATION: This project is authorized for construction in Section 401a of the Water Resources Development Act of 1986.

STATUS: Following the 1997 GRR, several authorized project measures have been constructed in the Lower Basin with others in the course of design or awaiting funding. In a letter dated April 6, 2015, the New Jersey Department of Environmental Protection (NJDEP) requested that the U.S. Army Corps of Engineers (USACE) initiate a reevaluation of the deferred Upper Basin of the Green Brook Authorized Project.  Given the significant time that has passed since the project was authorized in 1986 and since the release of the May 1997 GRR, the District initiated a Validation Study in order to validate the results of the current authorized project.

The Validation Study determined that implementation of the features with the Upper and Stony Brook Basins are not viable as they are not economically justified.  The study determined the constructed and unconstructed portions of the Lower Basin taken together are economically justified. None of the unconstructed features in the Lower Basin will require reformulation; however, it should be noted that the final design and construction for some systems of the Lower Basin with regards to their sizing are affected by future recommendations for the Upper Basin and Stony Brook Basins. The Final Validation Report, approved by MG Milhorn April 29th, 2020 recommends a General Reevaluation Report (GRR) be conducted to examine unauthorized alternatives that might provide flood risk management in the Upper Basin and Stony Brook Basin areas of Green Brook. The final PGM for the Validation report was signed and sent to HQ on 9 Feb 2021. The Validation Report stands as approved by the MSC Commander and the focus is on:  1 - continuing construction, and 2 – parallel to the construction, pursue budgeting of the GRR. BG Tickner has approved the Final Green Brook Validation Report package and has transmitted that concurrence memo to HQUSACE on 14 October 2021. 

Revised features could include non-structural work such as floodproofing, buy-outs, elevation of structures; channel modifications either small in scale or in combination with other measure(s); a diversion tunnel; levees or floodwalls; and other features. The FCSA for the Upper Basin was executed 28 September 2022 with NJDEP as the non-Federal sponsor and the Alternatives Milestone scheduled for February 2023.

Estimated Study Costs: The cost estimate for the Greenbrook GRR is approximately $3.2M.   


Nathanael Wales, PE
Project Manager
P: (917) 790-8731
U.S. Army Corps of Engineers, New York District
Programs and Project Management Division
26 Federal Plaza
New York, NY 10278