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Texas - Harris County - Addicks Reservoir

Case Number: 
Affected Counties: 
Harris County, TX
Preliminary map: 
Projected Effective: 
Project Status: 

Project Information:  Because of technological advances and additional local study efforts, the Harris County Flood Control District has an improved understanding of the amount and extent of the natural stormwater overflow from Cypress Creek into Addicks. The Addicks Reservoir watershed model and map update refines the existing hydrologic and hydraulic computer models for the Addicks Reservoir watershed. Revised floodplain delineations were prepared based on 1-foot contour interval (rather than on 2-foot contour interval) topographic maps, using 2008 Land Use Data (rather than on 2001 Land Use data). The engineering results were provided to the Federal Emergency Management Agency (FEMA) to prepare the preliminary Flood Insurance Rate Maps (FIRMs) for the watershed area.

FEMA released preliminary information on July 29, 2015.

FEMA received technical data submissions to refine the analysis and floodplain results during the formal Appeal and Comment Period.  FEMA has resolved these appeals with the support of HCFCD.  A set of revised preliminary panels is being prepared.

About the Project Area: The Addicks Reservoir watershed is located in western Harris County with a small portion crossing into eastern Waller County. Rainfall within the 138 square miles of the Addicks Reservoir watershed drains to the watershed’s primary waterway, Langham Creek (U100-00-00). The Addicks Reservoir watershed occasionally receives a significant amount of natural stormwater overflow from the Cypress Creek watershed during heavy rainfall events. Stormwater runoff from this watershed drains through the Addicks Reservoir and eventually into Buffalo Bayou.

Together with Barker Reservoir, Addicks Reservoir was built in the 1940s as part of a federal project to reduce flooding risks along Buffalo Bayou, which runs west to east through downtown Houston. The U.S. Army Corps of Engineers (the Corps) completed construction of Addicks Dam and the outlet facility in 1948. The Corps owns, operates and maintains the reservoir, including leases or permits for some compatible recreational uses within the basin. Operation of the outlet facilities controls discharges from the reservoir into Langham Creek, then into Buffalo Bayou.

Dates: Data Received from HCFCD (XX/XX), Preliminary Issuance (07/29/2015), CCO Meeting (09/24/2015), Appeals Period (03/24/2016-06/21/2016), Revised Preliminary Panels - PENDING

Project Meetings: See folder

Documents and Data: Preliminary Interactive Flood Map Index
Flood Insurance Study Volume 1

Flood Insurance Study Volume 3
Flood Insurance Study Volume 6
Flood Insurance Study Volume 8

Additional Resources: HCFCD – Flood Eduction Mapping Tool (Interactive Map); HCFCD – Addicks Watershed; HCFCD – Addicks Reservoir Mapping Update; HCFCD – Cypress Creek Overflow Management; What is Risk MAP?; FAQs - Flood Hazard Mapping