Floodplain Information and Mapping

Floodplain inquiries are handled by the Department of Public Works and Transportation (DPWT), which coordinates mapping with the Federal Emergency Management Agency (FEMA). Although almost any part of Baltimore County can flood, there are some areas more likely to do so than others, called floodplains. Baltimore County floodplains fall into two main categories, tidal and riverine.

  • Tidal Floodplains—Areas influenced by the astronomical tides such as the Chesapeake Bay and the tidal rivers adjacent to it. Tidal flooding results primarily from wind and waves and although dangerous, their effect is limited to areas below certain elevations.
  • Riverine/Nontidal Floodplains—Those areas inundated by streams fed by rainfall and which flow downstream by gravity. Such floodplains can be even more dangerous than tidal since water flowing under gravity can build up considerable energy on its way downstream and can easily wash away buildings, vehicles and people. Little creeks and brooks flowing just a few feet wide and shallow enough to wade across during dry weather may become raging rivers many feet deep and hundreds of feet wide in a flood event.

Fortunately there are resources available to identify flood-prone areas so no one needs to be caught by surprise. For interpretation of the data contained on the below maps, call Terry Curtis at 410-887-3117 or email tcurtis@baltimorecountymd.gov.

PRELIMINARY FLOOD INSURANCE RATE MAP

In accordance with FEMA, a multi-year project to reexamine Baltimore County’s flood zones and develop detailed, digital flood hazard maps has been completed. The new maps—also known as Digital Flood Insurance Rate Maps (DFIRM)—reflect current flood risks, replacing maps that are up to 15 years old.

VIEW THE FLOOD INSURANCE RATE MAP

INTERACTIVE FLOODPLAIN MAP APPLICATION

Use the online interactive mapping application to the Digital Flood Insurance Rate Map (DFIRM), which enables users to select, view and print predefined maps and reports about floodplains in Baltimore County. The data includes:

  • Floodplain data as published by FEMA
  • Data on Letters of Map Amendment (LOMA), Letters of Map Revision (LOMR) and all letters of map change, including the ability to download the LOMA

View instructions for using the application. For issues with the application, call Terry Curtis at 410-887-3117 or email tcurtis@baltimorecountymd.gov.

VIEW THE FLOODPLAIN MAP

REGULATIONS

The data in the DFIRM have an effective date of September 26, 2008 and should be used to comply with the Baltimore County Code 2003, Title 04 Department of Public Works and Transportation, Subtitle 02 Flood Insurance Rate Maps, Authority: Sections 32-8-202(a) and 32-8-203(d). New tidal floodplain maps and regulations were effective May 5, 2014.

FOR HOMEOWNERS

The worst of the floodplains are mapped on the Federal Flood Insurance Rate Maps (FIRMs) published by FEMA. Zones designated as special flood hazard areas on these FIRMs show:

  • Where the probability of flooding is one percent or more in any particular year
  • All of the tidal floodplains, but generally, only map riverine floodplains draining rainfall on areas of one square mile (640 acres) or greater

Under Federal, law mortgage lenders must require flood insurance coverage for properties in these areas. It’s important to note that ordinary homeowners insurance does not cover flood damage at all.

In order for Baltimore County to participate in the National Flood Insurance Program, under which our property owners may buy Federal flood insurance, we have to include certain provisions and restrictions in our building code and development regulations.

Baltimore County prohibits development by right in floodplains draining areas of 30 acres or greater, and restricts construction adjacent to drainage courses of any size. The County has an inventory of floodplain studies that map floodplains with drainage areas smaller than those mapped on the FIRM.

The Codes allow new construction in tidal floodplains but do not allow new development by right in riverine floodplains. The County also uses the one-percent annual chance flood as our definition for floodplain regulation; however, we use a more conservative definition for riverine floodplains than does FEMA. FEMA bases its riverine floodplain limits on runoff calculated on existing land use, presumably to avoid overcharging insurance premiums. But the County bases its riverine floodplains on runoff calculated as if the drainage area were developed to the maximum allowed by zoning. Our reason is to prevent upstream development from putting properties into a floodplain area where one was not mapped previously. That is why building permits and land development projects in Baltimore County are subjected to restrictions greater than those shown on the FIRM. Our inventory of riverine flood studies will usually reflect this “ultimate” floodplain as well.

In the case of riverine floodplains, if the one percent annual chance floodplain has not been defined and mapped, a developer or permit applicant will be asked to submit a study prepared by a licensed engineer for that purpose.

Please refer to the following resources for the legal authority supporting our floodplain regulations:

  • Section 32.4.414 Baltimore County Code
  • Section 32.8 Baltimore County Code
  • County Council Bill 49-24 (Building Code, including the International Building Code and the International Residential Code by reference)
  • County Council Bill 42-15 (Adopting the Federal FIRMs and placing special requirements on the tidal floodplains for building code purposes)
  • Development Plan Review Policy Manual
  • Department of Public Works and Transportation Design Manual

The Department of Public Works and Transportation is frequently asked about language found in real estate sales contracts for properties offered for sale in Baltimore County due to the following section of Baltimore County Code (1988 Code, Section 26-669) (Bill No. 173-93, Section 2, 11-17-1993; Bill No. 112-02, Section 2, 7-1-2004):

Section 32-8-208—Contract of Sale Requirement

(a) House removed from flood plain area. The following clause shall appear in any contract of sale or resale of a house, building or other structure that has been removed from a 100-year flood plain area: "The house, building or structure which is the subject of this contract has been removed from a 100-year flood plain."

(b) Failure to include required language. Failure to include the clause mandated by this section shall render the contract voidable at the option of the purchaser.

This clause is about a very specific and unusual situation. The County on occasion will purchase properties subject to severe flooding as a less-expensive alternative to providing drainage improvements to streams. This is a rare occurrence, and even more rare is the situation where property owners like the house so much that rather than have it demolished, they have it placed on a special truck and moved to a new lot. If a house is “removed from a floodplain” in this way, the structure could have residual flooding damage that would not be expected in a house offered for sale in an area not designated as a floodplain.

Real estate settlements usually include a flood certification advising whether a house is located in a FIRM floodplain and which flood insurance would have to be required by a mortgage lender, but that is something different.

ADDITIONAL RESOURCES

View Baltimore County's nuisance flooding plan, or learn more from the state and federal resources below: