A plan to rehabilitate the dam at the Woodcliff Lake Reservoir may create a scenario which makes flooding more likely along the Pascack Brook, according to Westwood Mayor John Birkner.
The plan involves working on the dam to strengthen it to withstand a 1,000-year storm, or a storm so severe it is likely to only occur once every 1,000 years. Church Road in Hillsdale will also be lowered. The Department of Environmental Protection is requiring United Water to undergo the rehabilitation project to ensure the dam holds.
As the dam is now, its gate can be raised in the event of heavy rain to prevent all the storm water from flowing into the brook at once. During construction, the gate will have to be kept at 89 feet, which is lower than usual, and it will not be able to be raised. This will increase the likelihood of flooding even in a moderate storm, Birkner said. The construction is expected to last two years.
"The more pressing issue is what happens to water levels in flood-prone areas during — not necessarily a natural disaster-type storm — the type of storm that we have seen flooding with even when the dam was at 91 feet," Birkner said.
Birkner said he wants to know if the state will help with the costs of damages from flooding while the gate is being rehabilitated, but he has not received an answer yet. The DEP is planning to hold a meeting about the project but has not settled on a date yet.
Westwood officials have also been attempting to get operations changed at the dam once the work is complete. A report by Boswell Engineering , so there is more room to raise it during a storm. Currently, the gates are only kept at 91 feet during the winter.