The concrete dam in Yantacaw Brook Park needs to be rebuilt to avoid what the Township Council termed a catastrophic failure resulting in flooding in the area. 

The 5-foot-tall dam at the southern end of the park has two purposes: to keep the water levels up in the park’s man-made pond, and to reduce the risk of Yantacaw Brook flooding its banks. 

The brook feeds the pond and then continues into the Third River through Bloomfield, Nutley and Belleville, where it meets the Passaic River.  Both Yantacaw Brook and the Third River were referred to by the Lenni-Lenape people as Yantokah or Yantacaw. 

In 2019, township officials submitted documentation on the dam’s condition to Essex County for inclusion in the county’s hazard mitigation report, which outlines hazards and corrective action plans for each municipality. 

“Existing dam is failing and does not meet current DEP regulations. Dam failure could result in flooding and property damage,” the report read.

On Sept. 29, Montclair’s council voted to hire GZA GeoEnvironmental to do an engineering study of the dam, which would be the first step toward rebuilding it.

GZA will perform four services for Montclair, according to council documents:

  • • Come up with a conceptual design to bring the dam into compliance with DEP regulations;
  • • Design spillway apron repairs, to correct existing deterioration;
  • • Develop an emergency action plan in the event of a catastrophic failure of the dam, and
  • • Perform dam inspections. 

The four services in the contract, covered by funds in the 2020 budget, are expected to cost no more than $36,825. The actual cost of the dam replacement will depend on the outcome of the study. 

Township Community Services Director Steve Wood said the township did not know exactly how old the dam is, and that the dam had only recently been classified as one. 

“The engineers are following NJDEP Dam Safety protocols and timelines for inspections and to determine modifications and maintenance improvements particularly with regard to the spillway,” Wood said. “We do not anticipate any maintenance repairs to be made prior to 2021. It is early in the analysis/design phase.”

Yantacaw Brook is located in Flood Zone A, a 100-year flood zone with base elevation undetermined. 

The dam is a Class IV dam, the smallest category of dam in DEP regulations. Class IV dams must undergo a regular inspection at least every four years. 

A hazard mitigation report compiled by Essex County includes the Yantacaw Brook dam as one of the township’s priority projects.

The report submitted to the county identifies the DEP as a potential funding source for the actual dam repairs, and the township Department of Community Services would oversee the project when it goes forward. 

The northern and southern ends of Yantacaw Brook, at the Montclair town lines, are identified as “repetitive loss” areas on a hazard map that Montclair submitted to the county, meaning they contain property that has received reimbursement from the National Flood Insurance Program at least four times in a given year. 

To take no action would see the problem become worse, the paperwork said. The dam cannot be removed, as that would increase flooding, and building a new dam upstream is not feasible due to property ownership. 

The 11.15-acre Yantacaw Brook Park is the site of the former Upper Montclair Country Club, which was established in 1901 as a five-hole golf course. The golf course was expanded in 1904, and by that time it included a new clubhouse and a man-made pond.

The Upper Montclair Country Club moved to its current site in 1929. The Yantacaw Park area was then home to a township-owned golf course until 1953, said township historian Mike Farrelly. He also noted that improvements were made to the dam between 1931 and 1959.