Floodplain Mapping Unit

Historically, New Jersey has taken a leading role in the development of a rigorous floodplain management program at the State level while supporting the same efforts at the Federal level with the Federal Emergency Management Agency (FEMA).

In 1929, N.J.S.A. 58:1-26 authorized a state agency to regulate structures within the natural and ordinary high water mark. In 1962, a second law N.J.S.A 58:16A (50-54), was adopted authorizing the Division of Water Policy and Supply, to study flood plain areas and to delineate such area by resolution. In 1972, the legislature adopted a third statue amending the 1962 Act which authorized the Division of Water Policy and Supply to delineate and mark flood hazard areas and to adopt regulations for these areas. Under the 1972 Act, N.J.S.A. 58:16A (50-66), the Department is authorized to adopt floodway regulations and to promulgate minimum standards for local rules and regulations concerning development in Flood Fringe areas.

The Division of Water Policy and Supply, now the NJ Department of Environmental Protection was authorized “to adopt land use regulations for the flood hazard area, to control stream encroachments, to coordinate effectively the development, dissemination, and use of information on floods and flood damages.” The state’s approach to effectively providing this information was to develop flood hazard area maps. The New Jersey maps, which predated the Federal maps, indicate the special flood hazard area or 100-year flood, the 0.2 ft rise floodway, and delineates the New Jersey Flood Hazard Area Design Flood (NJFHADF). The NJFHADF is based on the 100-year flood discharge plus 25%. These maps preceded similar efforts at the federal level.   Early State mapping efforts include the Central Passaic Basin maps, Stony Brook Flood Hazard Report prototype published in 1967 and the Flood Hazard Report booklets for the Raritan River Basin published in 1972 and 1973.

FEMA has transitioned from their Flood Map Modernization Program (Map Mod) to Risk Mapping, Assessment and Planning (Risk MAP). The Map Mod program began the work of conducting a large-scale overhaul of existing paper flood hazard maps. Individual paper municipal formatted studies were transformed into digital Geographic Information System (GIS) county-wide studies in NAVD88 Datum.  Risk MAP provides communities with flood information on a watershed basis and tools they can use to enhance their mitigation plans and better protect their citizens. Through more accurate flood maps, risk assessment tools and outreach support, Risk MAP builds on Map Mod and provides more information to make informed decisions about reducing risk.

As part of Risk MAP initiatives, a suite of flood risk products is developed for each county, including: a flood risk report to provide stakeholders with a comprehensive understanding of flood hazard and risk exposure within their community and watershed; a flood risk map that depicts county and community boundaries in relation to areas of risk within the study area; and a flood risk database that will be the primary source to access information collected and developed during the flood risk assessment process. Additional products may include information useful to municipalities, homeowners, emergency management offices, and insurance companies such as: a summary of changes to the new digital Flood Insurance Rate Map (FIRM) since the last FIRM; flood depth and grid analysis; flood risk assessments; and the identification of areas of mitigation potential.

In 2006, the NJDEP and FEMA signed a Cooperating Technical Partnership Agreement (CTP) to perform map production together to build the next generation of FEMA and State flood mapping. New Jersey will continue to take the lead in prioritizing projects, coordinating available data sources and conducting outreach, and all essential components in the data production and map adoption. Moving forward, NJDEP will be developing new floodplain data, producing digital FIRMs and post-preliminary processing.

New Jersey will integrate its mapping program with the FEMA program. This integration hinges on creating FEMA FIRMs for New Jersey which delineate the New Jersey Flood Hazard Area Design Flood (NJFHADF) on the mapping and plots the NJFHADF water levels on the stream profiles, the state’s regulatory standard. Currently, some FEMA FIRMs do not have this data The State is obligated to compare the State flood elevations and floodway with the FEMA data for higher flood levels and wider floodways. By including the NJFHADF on the FIRM, the state would be able to use the FEMA FIRMs as the single source for both Federal and State floodplain management, freeing up staff resources and reducing errors.