Projects & Studies

Cedar Bayou

Drainage Area Watershed Population Open Stream Miles Primary Streams
202 Sq. Miles 36,878 (Harris County portion) 128 Miles Cedar Bayou

cedarbayou.jpg

Watershed Overview

The Cedar Bayou watershed is the easternmost watershed in Harris County, and Cedar Bayou generally serves as the border for Harris County with Chambers and Liberty counties. The cities of Baytown and Mont Belvieu are located within the watershed, which encompasses nearly 200 square miles. Cedar Bayou flows in a southward direction from its headwaters in Liberty County to its mouth at Galveston Bay. There are about 128 miles of open streams within the watershed, including the primary stream and tributary channels. The main stem of Cedar Bayou is approximately 40 stream miles in length and directly impacts Harris County, Chambers County, Liberty County and the City of Baytown. Based on 2010 Census data, the estimated population within the watershed is just over 59,000. 

CedarBayou_ds_from_ramsey_rd.jpg
Mowing Downstream from Ramsey Road, Cedar Bayou, 2003.

Although a large floodplain exists in the upper and middle reaches of Cedar Bayou, this portion of the watershed is sparsely developed, and therefore, the flooding is more threatening to roads and agriculture than structures like houses and businesses. Flooding along the tributaries in the urbanizing portions of the watershed is a concern.

Background

The Cedar Bayou watershed has a known history of flooding, with several noteworthy rainfall events resulting in more than $13M in damages since the late 1970’s. The watershed has experienced several significant flooding events, including storms in June 1979, June 1981, August 1983 (Hurricane Alicia), May 1989, October 1994 (worst on record), June 2001 (Tropical Storm Allison), September 2008 (Hurricane Ike), April 2009, and October 2015. After the Halloween 2015 flooding, the Harris County Flood Control District chose Cedar Bayou for a planning study. Recent rainfall events have resulted in additional damages, with rainfall totals and stream elevations reaching 100-year levels in parts of the watershed. This flooding has resulted from a combination of riverine overflow from Cedar Bayou and its tributaries, and coastal storm surge from Galveston Bay, where Cedar Bayou empties. Numerous smaller storms have forced Cedar Bayou out of its banks and caused isolated damages and roadway flooding, which disrupts the roadway network and limits mobility in the watershed.

Land Use

Much of the Cedar Bayou watershed is undeveloped with the exception of the City of Baytown, located in Harris and Chambers counties, and the City of Mont Belvieu, located in Chambers County. The watershed is primarily rural and agricultural, with the most development activity related to large commercial grass farming operations. Development of residential housing and/or industrial and commercial facilities is expected to increase slowly.

Environment

Most of the primary stream and floodplain is environmentally sensitive due to the saltwater marshlands in the lower reaches and the undeveloped natural channel reaches upstream of Baytown. The Texas Parks and Wildlife Department considers the area around the mouth of Cedar Bayou to be a critical wildlife habitat.

Maintenance Projects

The Harris County Flood Control District has undertaken several maintenance projects along tributaries in the Cedar Bayou Watershed in the past year to improve the stormwater conveyance of the channel network. Selective clearing, or the removal of dead trees and obstructive vegetation, has occurred along Cedar Bayou tributaries identified as Q125-00-00, Q126-00-00 (Krenek Ditch), and Q136-00-00. Desiltations, or the removal of sediment in the bottom of the channel, has occurred along Cedar Bayou tributaries identified as Q128-00-00 (Adlong Ditch) and Q128-05-00.