Natural & Beneficial Functions / Flood Maps

Natural & Beneficial Functions

Floodplains provide a wide range of benefits to human and natural systems. They serve as flood storage and conveyance and reduce flood velocities and flood peaks. Water quality is improved through the soil and vegetation's ability to filter out nutrients and impurities from runoff and process organic wastes. Floodplains and wetlands provide breeding and feeding grounds for fish and wildlife, create and enhance waterfowl habitats, and protect habitats for rare and endangered species. They provide open space, aesthetic pleasure, and areas for active uses such as parks and playgrounds. The floodplains are an important asset to League City.

Flood zones within League City primarily trail along the following boundaries of Clear Creek to the north, Galveston Bay to the east, Benson Bayou, and Geisler Bayou to the south central, Dickinson Bayou to the southwest, and Clear Creek to the north. The city also has numerous secondary watersheds and other drainage features that carry water across the city's 55 square miles.

One unique feature about League City is its numerous live oak trees that were planted in the late 1870s. Besides creating a quaint atmosphere in the city, the live oak trees also reduce stormwater runoff in urban areas by up to 17%. The canopy of a single large live oak can intercept up to 28% of a major rainfall, thereby reducing the effects of flooding. For more information on how the trees benefit League City, visit the League City Historical Society.

Flood Insurance Rate Maps

Flood Insurance Rate Maps are issued by FEMA to identify different levels of flood risks. The Flood Insurance Rate Maps are primarily used for flood insurance purposes, but they also provide a basis for League City to regulate development within those areas. The location of a property relative to certain flood zones indicates what restrictions may be placed on new and substantially improved construction. FEMA Flood Insurance and Flood Maps explains the different flood zones.

The historic Flood Insurance Rate Maps (FIRM) and historic Flood Insurance Study (FIS) are available for viewing on three different platforms: 1) through the links below, 2) the Helen Hall Library, and 3) directly to the FEMA Map Service Center. The City uses the most current Flood Insurance Rate Map effective date August 15, 2019, for compliance purposes.

FEMA and its contractors are in the process of updating the flood maps for Galveston County and Harris County. The adoption of the maps are due to be finalized next year. At that time, the public will be given an opportunity to view the maps and provide comments. Citizens will be notified of the mapping status updates via the City website or by visiting the FEMA website. You can get ahead on the changes in the flood maps by checking out the FEMA document entitled Understanding the Changes to Your Community's Flood Insurance Rate Map.

Texas Natural Resources Information System

The Texas Natural Resources Information System (TNRIS) is gathering data for a high water mark inventory for the state. The public is encouraged to send their pictures, emails, and other information to the agency. High water marks, or debris lines, can establish a basis for understanding typical flooding events and can help experts estimate the kind of damage future floods may bring.