Floodplain Mapping for Clear Brook

DNREC and the federal government are working on an update of floodplain maps for Clear Brook, near Seaford in Sussex County. The study involves new data and engineering models. DNREC is gathering input from local property owners and businesses as part of the update.

Update (4/1/2021): FEMA has issued the Letter of Map Revision (LOMR) for this study. The map changes are scheduled to go into effect on August 18, 2021, following a 90-day appeal period.

Update (3/1/2021): The proposed floodplain mapping displayed and linked below has been updated based on the results of a review by FEMA. Both DNREC and FEMA will publish public notices of the map change. A 90-day appeal period will begin after FEMA issues its second of two public notices about the map update.

An update to the Sussex County Flood Insurance Rate Map resulted in changes to the mapped floodplain areas along Clear Brook. These changes may have flood insurance implications for local homeowners.

DNREC has collected public comments on a process called a Letter of Map Revision to revise the floodplain.

The Federal Emergency Management Agency (FEMA) maps floodplains in the United States as part of the National Flood Insurance Program (NFIP). FEMA uses these maps, called Flood Insurance Rate Maps (FIRMs), to set flood insurance rates. Communities and local governments use them to manage flood risk. The maps are updated when there are changes in a watershed or stream or when better data or modeling is available.

For more information, contact the floodplain management program, at 302-608-5500

A Letter of Map Revision

Floodplain mapping for Clear Brook will be revised through a FEMA process called a Letter of Map Revision (LOMR). Revising a floodplain map involves data analysis and modeling. New mapping is developed using topographic data along with hydrologic and hydraulic modeling.

The proposed floodplain mapping generally shows a reduction in the in the mapped floodplain upstream of Hearns Pond and a slight expansion of the mapped floodplain between Hearns Pond and Williams Pond.

Example: Proposed Changes Around Hearns Pond

Current Floodplain Areas

Clearbrook Current Floodplain

Proposed Floodplain Areas (Updated)

Clear Brook Floodplain, Updated

Sussex County FIRM Update

A Sussex County FIRM update took place in 2018. The floodplain for Clear Brook was re-delineated using models developed in 1995 and updated topographic data. The result was a large expansion of the floodplain along the stream near Hearns Pond.

The change extended the Zone AE “high risk” floodplain, shown on the Current Floodplain Map in blue, into areas that may not be high risk, based on visual and anecdotal observations.

The 1995 models do not reflect changes to the Hearns Pond and Williams Pond dams.

Hearns Pond Dam, damaged by storms in 2001 and 2006, was rehabilitated by DelDOT and DNREC. Construction, completed in 2017, included a new, larger spillway. The Williams Pond spillway was replaced by DelDOT in 2011.

These spillways are included in the engineering models of the floodplain for the map revision currently underway.

Flood insurance

Homeowners’ insurance does not cover flood damage. Flood insurance is available through the National Flood Insurance Program (NFIP).

Homes with federally-backed mortgages that are within Special Flood Hazard Areas must have flood insurance.

Changes to the Clear Brook floodplain maps may have flood insurance implications for local homeowners.

Owners of homes newly mapped into the floodplain may have to buy flood insurance once the map change goes into effect. Some may find their homes no longer in the mapped floodplain. They may be eligible for flood insurance at a reduced rate (called a Preferred Risk Policy).

For more information about flood insurance, contact your your insurance provider or learn more at