By Tom Gilbert, Co-Executive Director, New Jersey Conservation Foundation
The timing was coincidental, but could not have been more poignant. On July 16, Gov. Phil Murphy declared a state of emergency due to widespread flash flooding, landslides, and downed trees from severe thunderstorms that swept through the state. The next day, new state regulations to protect people and property from river flooding went into effect.
More than three years in the making, the state’s Inland Flood Protection Rule is an acknowledgement that climate change is making New Jersey warmer and wetter. Because of the strong likelihood of more frequent and intense rainfall in the coming decades, the rules require new development near rivers and streams to be built higher, drier and safer.
“The whole goal is to protect people from the dangers of flooding,” said Vincent Mazzei, state floodplain administrator for the New Jersey Department of Environmental Protection (DEP) at a webinar this week to explain the new regulations.
New Jersey has a long history of vulnerability to flooding. Many of the state’s oldest settlements, established during the colonial era, were built along navigable waterways – the main transportation corridors of the time. Mills and their surrounding communities were also built along rivers to take advantage of water power.
Since the first cities and towns were founded, New Jersey has grown to become the nation’s most densely populated state, and development pressure remains strong. New development increases the risk of flooding, since more buildings and pavement mean less area where rainfall can be absorbed into the ground before flowing into rivers and streams.
Add intensifying rainfall in the future, and it’s a recipe for disaster.
The Inland Flood Protection Rule aims to prevent such disasters by strengthening two types of development regulations:
- Floodplains — The new rules more realistically define the boundaries of riverine floodplains, the areas at highest risk of inundation during storms. Previous floodplain boundaries didn’t account for the impacts of climate change or continuing development, and did not reflect actual conditions. Under the new regulations, the elevation of habitable first floors must be two feet higher than indicated on old DEP state flood maps, and three feet higher than indicated on Federal Emergency Management Agency (FEMA) maps.
- Stormwater — The new rules require all new major developments to address stormwater runoff — which contributes to both flooding and water pollution — using updated rainfall data and projections. Retention basins, green infrastructure and other stormwater management systems must be designed to handle higher rainfall totals in the future. Prior to the new Inland Flood Protection Rule, New Jersey’s land use regulations had been based on outdated rainfall data from 1999 and earlier. But, as DEP officials pointed out, in a changing climate, data from the past is not an accurate predictor of current and future flood risk.
In 2020, the DEP released a report predicting more and longer heat waves by 2050, and a temperature increase of 4-6 degrees Fahrenheit. Over the same period, the report projected, the amount of precipitation will increase by 4 to 11% annually, and heavy downpours will be two to five times more frequent.
The same year, Gov. Murphy signed an executive order directing the DEP to integrate climate change considerations – including sea level rise and chronic flooding – into its regulatory and permitting process.
Momentum for the Inland Flood Protection Rule increased after September 2021, when the remnants of Hurricane Ida dumped up to 11 inches of rainfall on a landscape already saturated from previous storms. Thirty New Jerseyans died in the flash floods – more than in any other state – and hundreds of homes and businesses were damaged or destroyed.
Gov. Murphy and the DEP deserve a lot of credit for taking action to better prepare the state for the impacts of climate change that are already being felt, and are projected to worsen in the coming decades. Lives will be saved, and homes and businesses spared in the future.
“Planning ahead is not the easy choice, but it is certainly the right one, and one you don’t regret,” said Katrina Angarone, the DEP’s assistant commissioner for watershed and land management. “That’s certainly what the Inland Flood Protection Rule is all about.”
For more information on the Inland Flood Protection Rule, and to view the recent webinar, go to the DEP webpage at https://dep.nj.gov/inland-flood-protection-rule/. The website includes a New Jersey Flood Indicator Tool, an interactive map that residents can use to find out how close their homes are to the newly-expanded floodplains.
As part of its outreach, the DEP held an online question and answer session on Aug. 1.
To learn more about protecting New Jersey’s land and natural resources – including properties along waterways that can help prevent flooding – visit the New Jersey Conservation Foundation website at www.njconservation.org or contact me at email@example.com.