In Harris County, only the areas
impacted by coastal flooding are being updated under TXCHART. The riverine
flood hazard data was updated on the effective Harris County FIRMs in 2007. Several
flood studies are currently ongoing in Harris County.
Harris County was founded in December
1836 as Harrisburg County. The name was changed to Harris County in December
In 2010, Harris County has a population
of 4,092,459, making it the most populous county in Texas, and the third most
populous county in the United States.
The region in Harris County receives
annual rainfall averages of 48 to 52 inches. Several historic storms affected
the area, including Hurricane Ike in September 2008, and Tropical Storm Allison
in June 2001. Tropical Storm Allison was especially destructive and caused
significant flooding even outside the designated Special Flood Hazard Areas. To
mitigate this, the Tropical Storm Allison Recovery Project (TSARP) was
established, culminating in new Special Flood Hazard Area (SFHA) maps in June
Harris County entered the regular
National Flood Insurance Program (NFIP) in May 1970. Many cities in Harris
County also joined the regular NFIP during the 1970s and 1980s.
Harris County and several other
communities within the county participate in the Community Rating System (CRS)
and enjoy a five to 20 percent discount on flood insurance premiums as of June
For flood insurance questions, call the NFIP Hotline -
1-800-621-3362.(press 2 for insurance)
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. Rural and agricultural uses have historically dominated the upstream regions of the watershed, but residential and commercial developments are rapidly growing. There are 159 miles of open waterways in the Addicks Reservoir watershed, including Langham Creek and its major tributaries, such as South Mayde Creek (U101-00-00), Bear Creek (U102-00-00) and Horsepen Creek (U106-00-00). Based on the 2010 U.S. Census, the estimated population of the Addicks Reservoir watershed is 295,694.
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. Environmentally-sensitive areas and a wide range of wildlife habitats exist within the reservoir boundaries and along the upper tributary reaches that extend into the Katy Prairie.