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Addicks Reservoir Watershed

Updated November 2013

Map illustration of Addicks Reservoir Watershed

Watershed Overview
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.

Active Studies
  • Addicks Reservoir Watershed Model and Map Update - The Addicks Reservoir Watershed Model and Map Update study is updating the hydrologic and hydraulic computer models for the Addicks Reservoir watershed that will result in revised Flood Insurance Rate Maps (FIRMs or floodplain maps). Because of technological advances and additional studies, the Flood Control District has an improved understanding of the amount and extent of the natural stormwater overflow from Cypress Creek into Addicks. When this effort is complete, revised FIRMs for the Addicks Reservoir watershed will be produced based on 1-foot contour interval (rather than on 2-foot contour interval topographic maps) and based on 2008 Land Use data (rather than on 2001 Land Use data). The draft revised FIRMs are under review by FEMA. This study also will produce other map products as a result of the Harris County Flood Control District’s participation in a Federal Emergency Management Agency (FEMA) pilot program called Risk MAP (Mapping, Assessment and Planning). This study will focus on the “Mapping” component of the Risk MAP program. The maps will be made available to the public. Harris County is the first county in FEMA Region VI to participate in the Risk MAP program.
  • Cypress Creek Overflow Management Plan - The Addicks Reservoir watershed occasionally receives a significant amount of natural stormwater overflow from the upper Cypress Creek watershed during heavy rainfall events. To understand and manage this overflow, a study has been initiated that will result in policies, technical criteria and guidelines to reduce flood risks that are acceptable to area interests and reflect the unique hydrologic conditions in the area. The study area includes upper Cypress Creek (upstream of Highway 290) and the drainage areas upstream of Addicks and Barker reservoirs, including Langham Creek, Bear Creek and South Mayde Creek. Approximately 60 square miles of the upper Cypress Creek watershed originate in Waller County and drain into Harris County. The Flood Control District and Harris County have received a grant from the Texas Water Development Board to partially support this study effort. The first of three planned public meetings was held in August 2012. Two additional public meetings will be held during the course of developing the plan. See www.hcfcd.org/cypresscreekoverflow for further information.
  • Frontier Program - The Frontier Program is a way to accomplish an orderly drainage infrastructure in concert with future land development. Working in partnership with landowners, the Frontier Program identifies strategies unique to specific areas of the county that are distant from existing drainage infrastructure. These strategies will better mitigate increased stormwater runoff, offer opportunities to provide community amenities through development of recreation and open space areas, and enhance or preserve the area’s natural resources. Individual landowners and developers tend to adhere to site-specific approaches to development that result in isolated detention basins and minimum-width channels for stormwater management. In contrast to site-specific approaches, a regional plan facilitates construction of a channel corridor with wide flood benches, gentle side-slopes, storage volume within the corridor cross-section for mitigation of floodplain and development impact and outfall depth. The wider channel corridor in a regional approach allows for replacement of natural resource functions that would be lost and habitats that would be inadequate in a piecemeal, site-specific approach.
Active Capital Projects
In the past 20 years, the Harris County Flood Control District has spent nearly $12 million on capital projects in the Addicks Reservoir watershed. The completed capital projects include channel improvements along Langham Creek and diversion channels on Bear, Langham and Horsepen creeks. Active capital projects include implementation of concepts from the Frontier program and excavation of stormwater detention basins.

  • Upper Langham Creek Frontier Program - The purpose of the Upper Langham Creek Frontier Program is to implement key elements – including right-of-way acquisition, pipeline adjustments, design and construction of control structures, and environmental mitigation – of a regional drainage plan that embraces concepts from the Flood Control District’s Frontier Program and uses funding from development impact fees. The plan includes a 700-foot-wide corridor for the stream and its floodplain along with two detention basins. Excavation of the corridor and basins will be conducted by property owners – primarily developers – as their properties are improved or developed. This project was authorized by the Harris County Commissioners Court and will advance in phases.
  • Stormwater Detention Basin at John Paul's Landing Park - The Flood Control District is supporting Harris County Precinct 3 efforts to develop a regional park and stormwater detention basin within John Paul’s Landing Park (U502-02-00), which is located in the Upper Bear Creek and Upper Langham Creek area. While the Flood Control District completes a wetlands mitigation project in support of this project, a portion of the stormwater detention basin has been excavated through an excavation and removal agreement. Since 2011, the contractor has removed more than 1.1 million cubic yards of soil from this site. A future capital project is planned to complete the first phase of the basin. The remainder of the basin volume will be excavated on an as-needed basis by developers as a part of the Upper Langham Creek Program.
  • Site Improvements and Wetlands Construction - This project (K700-01-00-E001) will create and restore approximately 95 acres of wetland habitat on the Katy Prairie near the intersection of Katy-Hockley and House Hahl roads. The area provides required mitigation for other projects that will impact native wetlands, specifically the Greenhouse Stormwater Detention Basin on Langham Creek (U100-00-00), northwest of the FM 529 and Barker-Cypress Road intersection in the Addicks Reservoir watershed, and the John Paul’s Landing Stormwater Detention Basin on a Bear Creek tributary, near the intersection of Katy-Hockley Cutoff and Sharp roads. The wetlands project, which included planting bog rush, swamp smartweed, duck potato, powdered thalia and maidencane, began in 2013 and will cost approximately $203,000.
Recently Completed Capital Projects
  • Upper Horsepen Creek Stormwater Detention Basin - In late 2012, the Flood Control District completed the final phase of construction on this $1.36 million project (U506-05-00), located on a 175-acre site near the intersection of Barker-Cypress and West roads in northwest Harris County. The final phase included construction of a weir structure, which controls the timing and amount of stormwater that flows into a detention basin, and significant re-grading of the detention basin’s slopes. During times of heavy rain, rising stormwater in Horsepen Creek now flows into the basin via the weir and is temporarily stored until water levels drop. The basin has the capacity to detain approximately 360 million gallons of stormwater and will help reduce flooding risks for those who live downstream along Horsepen Creek. Harris County Precinct 3 is developing a county park at the basin, with trails, playgrounds, a dog park, parking lots and other recreational facilities.
Routine and Completed Maintenance Projects
The Harris County Flood Control District oversees more than 2,500 miles (about the distance from Los Angeles to New York City) of bayous and creeks and routinely performs maintenance projects to repair bayous and stormwater detention basins that have experienced erosion, slope failure and sediment buildup. The Flood Control District also plants native grasses, wildflowers and trees to help reduce erosion and lower mowing costs along bayous and stormwater detention basins in the Addicks Reservoir watershed.

  • Mowing and vegetation maintenance - The Flood Control District performs routine cyclical maintenance, including mowing of approximately 500 acres along bayous, creeks and stormwater detention basins in the Addicks Reservoir watershed. The Flood Control District also performs selective clearing of invasive trees and vegetation.
  • Tree and wildflower plantings - Cedar elm, loblolly pine and red maple are just a few of the tree species that were planted along two stormwater detention basins and a tributary identified as U119-00-00 in 2012. Along Langham Creek and U119-00-00, the Flood Control District planted several species of wildflowers, such as clasping coneflower, drummond phlox, Indian blanket and lance-leaf coreopsis in 2008 and 2011.
  • Horsepen Creek Maintenance Project - This maintenance project (U106-00-00-X024) removed accumulated sediment along a 3.25-mile section of Horsepen Creek from State Highway 6 downstream to the Addicks Reservoir. The project addressed spot erosion and pipe repairs along sections of the creek’s side slopes to help reduce the amount of eroded soil that falls into Horsepen Creek. The project was completed in late 2012 at a cost of approximately $1.4 million.
Active Maintenance Projects
  • Dinner Creek Channel Restoration Project - This project (U120-00-00-X007) will repair severe slope erosion and remove sediment from a 4,800-foot section of this Langham Creek tributary, from Greenhouse Road to Freeman Road. Surveys have found sinkholes and other examples of erosion, caused by overbank drainage and natural erosion due to poor soil quality. The project, which involves replacing 25 damaged interceptor structures, installing riprap to armor the slopes, and removing sediment, is expected to be completed in 2014.
  • Erosion Repairs in the Bear Creek watershed - This project, Z100-00-00-X190, will repair moderate to severe erosion and remove sediment buildup in a section of Bear Creek (U102-00-00) between Greenhouse and Fry roads, and in a smaller Bear Creek tributary (U102-25-00).



Addicks Reservoir Watershed Stats:

Drainage Area Watershed Population Open Channel Miles Primary Streams
138 Sq. Miles 295,694 159 Miles Bear Creek
Horsepen Creek
Langham Creek
South Mayde Creek


Click on any of the watershed links below (also found in the in the left nav) to view detailed information about each of Harris County's watersheds.

> See also Watersheds & Channels Reference Guide PDF


> Addicks Reservoir
> Armand Bayou
> Barker Reservoir
> Brays Bayou
> Buffalo Bayou
> Carpenters Bayou
> Cedar Bayou
> Clear Creek
> Cypress Creek*
> Galveston Bay
> Greens Bayou
> Hunting Bayou
> Jackson Bayou
> Luce Bayou
> San Jacinto River
> Sims Bayou
> Spring Creek
> Spring Gully & Goose Creek
> Vince Bayou
> White Oak Bayou
> Willow Creek

Harris County Flood Control District
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