Discover Galveston Bay

The Galveston Bay system is a complex ecosystem and a valuable resource for the state and the nation. It provides natural resources, ecological services, recreational opportunities, transportation links, economic benefits and aesthetic rewards.

To preserve the bay it is necessary to understand the system’s composition, the processes that link its components and how it interacts with its environs.


Galveston Bay is the largest and most biologically productive estuary in Texas, and sits adjacent to one of the most heavily urban, industrialized areas in the nation. Approximately 4.5 million people reside in the five counties surrounding Galveston Bay (Brazoria, Chambers, Galveston, Harris, and Liberty Counties), making the Houston metropolitan area the fourth most populous in the nation. That figure represents over 75 percent of Texas’ coastal population. While the western side of Galveston Bay is occupied by the urban metropolis, the eastern side remains largely rural.

Galveston Bay, its bayous, and diverse natural features make this region geographically unique, afford an array of recreational opportunities, and play an essential role in maintaining our quality of life. It is composed of four major sub-bays: Galveston, Trinity, East and West Bays. While Galveston Bay’s combined area is 384,000 acres or 600 square miles, it is very shallow; averaging only 7 feet. It is surrounded by 232 miles of shoreline. Extending inland from this shoreline and the shorelines of the bay’s tributaries, is 27,000 square miles of land that we call the Galveston Bay watershed.

Natural processes operating over geologic time created Galveston Bay and continue to slowly modify the Bay today. The two upper bays, Galveston and Trinity, were formed approximately 4,500 years as many modern estuaries are, through the drowning of river valleys as sea levels rose after the last Ice Age. The two lower bays, East and West Bay, are coastwise lagoons that were segregated from gulf waters by the linear barrier system, which developed around 4,000 years ago as sea level reached near present levels. East Bay formed as a result of Bolivar Peninsula; West Bay formed landward of Galveston Island.

Although natural processes are at work modifying the Bay, the most visible changes have come at the hands of humans.

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Photo of Cedar Bayou Watershed sign


The estuary system is greatly affected by natural processes and human activities occurring in its watershed, the area of land from which water drains to tributary rivers, bayous, streams, and ultimately Galveston Bay itself. The important relationship between the bay waters and the surrounding landscape cannot be overstated: the estuary’s physical, chemical, and biological quality is directly impacted by the quantity and quality of freshwater draining from its watershed.

The 24,000 square miles of the Galveston Bay watershed dwarfs the 600 square miles covered by the bay’s open waters. It reaches as far north as the Dallas-Fort Worth area, draining to the Trinity River which, in turn, ultimately flows to Galveston Bay. Due to the large areal coverage and presence of the urbanized areas within the watershed, approximately half the population of the state of Texas lives within its boundaries and has a large potential impact on the estuary.

The “lower” Galveston Bay watershed is defined as the 4,000 square mile  area draining to the Bay downstream of two major impoundments: Lake Houston on the San Jacinto River, and Lake Livingston on the Trinity River. Due to attenuation provided by the two reservoirs, the lower watershed more directly contributes pollutant loadings to the Galveston Bay system than does the “upper” Galveston Bay watershed. It is within this lower watershed that the Galveston Bay Estuary Program had focused its efforts.

Each stream and bayou in the lower Galveston Bay watershed has its own subwatershed. We all live in a subwatershed and affect the quality of our local water body by your daily activities. In fact, contaminated storm water runoff, or non-point source pollution, from our businesses, industries, farms, roads, parking lots, septic tanks, marinas and residential yards is the number one water quality problem facing the estuary.


An ecosystem is a natural system that includes all of its living and non-living things. The Galveston Bay ecosystem is composed of a complex set of overlapping habitats that function with inter-linking energy and materials processes. The integrity of these distinct but interacting habitats is vital to the continued natural function and life-support capability of the estuary. The abundance of nutrients and the diversity of available habitats within the estuary provide for very high levels of biological productivity.

The Galveston Bay Estuary habitat types include:

    • Uplands
    • Wetlands
    • Open-Bay Water
    • Open-Bay Bottom
    • Oyster Reefs
    • Seagrass Meadows
    • Intertidal Mud Flats

Loss of habitat, especially wetlands and seagrasses, by a range of human activities is the top overall priority problem facing the estuary. The well-being of these habitats is partially dependent on distant events, such as the spawning of shrimp and finfish in the gulf or storm water runoff from a remote watershed. This implies the need for a watershed-level approach to management of the system.

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Photo of West Bay

Galveston Bay’s Living Resource

Galveston Bay is home to a myriad of organisms. The Bay’s living resources range from microscopic planktonic algae and bacteria that drift with the currents to large mammals such as the bottlenose dolphin.

Just as Galveston Bay’s different habitat types are interconnected, so too are the Bay’s living resources. These organisms occupy different feeding, or trophic levels, in the estuarine food chain. While all of the Bay’s organisms are integral to ecosystem function, some of the more visible or economically important species are highlighted in the following groups:

Important Commercial and Recreational Fish Species

    • Colonial Waterbirds
    • Waterfowl
    • Shorebirds
    • Migratory Birds
    • Reptiles
    • Mammals

The fish and wildlife resources provide some of the Bay’s greatest economic, recreational and aesthetic assets. Additionally, many of these species are high in the food chain and are therefore important indicators of the health of estuarine food webs. Considerable scientific and regulatory resources are devoted to studying these populations.

The population size of a given species is determined by many relevant factors; among them are habitat (both quantity and quality) and degree of environmental contamination. Most of the Bay’s living resources appear to be in good health, with some exceptions posing management concerns.

History & Culture

Archaeological evidence shows that humans have been using the resources of Galveston Bay for at least 5,000 years. Early hunter-gatherers modified the bay environment by harvesting shellfish and other wildlife, producing shell middens and introducing plants from other ecoregions.

After 1800, settlers exploited the fish, shellfish, prairies and forests in and around the bay to develop the early fishing, cattle and lumber industries. Commercial fishing for shrimp, oysters and fish continues today with modern technology, but the composition of the catch has changed.

In addition to its biological resources, the bay’s physical resources were utilized as well. The bay and its tributaries yielded construction materials in the form of shell, sand and clay. Ranch land composed of upper prairies and lower salt grass marsh areas were used over time for other purposes including farming, oil extraction and industrial and urban development. Riparian timber resources became scarce and the lumber industry disappeared from the vicinity of Galveston Bay.

Beginning in the mid-1800s, alterations of the Bay for navigation include channels to three major ports and many smaller harbors. Dredged material from the Gulf Intracoastal Waterway, the Texas City Channel, the Galveston Channel and the Houston Ship Channel have been deposited on the open bay floor or into designated containment areas creating planned and unplanned islands which alter bay currents. Heavy exploitation of buried shell and groundwater produced detrimental effects. In the early- to mid-1900s, growth of the petroleum industry led to changes of land use in and around Galveston Bay.

The region has exhibited continuous immigration and economic expansion over most of the past 50 years. Much of the region’s growth has been attributed to the construction of the Houston Ship Channel and the discovery of oil in the early part of the twentieth century. The ascent of the Houston metropolitan area to the major population and industrial center it is today, however, has taken place largely since World War II. Houston’s population gains during the 1970s and early 1980s were remarkable.


Galveston Bay plays a crucial role in the economic health of the Houston Metropolitan Area. Galveston Bay assets contribute billions of dollars to the region’s economy and supports employment of tens of thousands of people through several key water-based industries such as recreational and commercial fishing , shellfish harvesting, and tourism. It’s ports, transportation industries, and proximity to rich petroleum reserves in the Gulf of Mexico, Caribbean Sea, and South America, form the core of its economy. The pleasantry of having a coastal treasure nearby attracts people to the region. Our region’s prosperity is dependent on Galveston Bay’s viability.

Galveston Bay does more than support the human and environmental infrastructure that drives our economy. It provides seafood, recreation, peace and solitude. People come from all over the country to go fishing in Galveston Bay, and from all over the world to witness the great migrations of hundreds of species of migratory birds, which travel along three of North America’s flyways through the Galveston Bay area. The Bay and watershed offers other recreational opportunities, from swimming on clean beaches or canoeing in tree shaded bayous to capturing glimpses of rare piping plovers and Attwater prairie chickens, or seeing the graceful dance of a dolphin from the Bolivar ferry. The Bay enhances the quality of life of those living around it.

Photo of Tug Boat

Galveston Bay has supported economic growth in the region and is surrounded by one of the most urbanized and industrialized areas in Texas and the nation. Resources in the Galveston Bay watershed have been utilized for construction, transportation, oil, gas and petrochemical production, water supply, fisheries, agriculture and recreational uses.

Port of Houston is the largest port in the U.S., based on foreign tonnage, and the 2nd largest in domestic tonnage. It is the 6th largest port in the world.

About 90,000 registered pleasure boats and the 3rd highest concentration of privately-owned marinas in the U. S.

Contributes one-third of the state’s commercial fishing income and over one-half of the state’s recreational fishing expenditures.

Shrimp accounts for nearly half the total Galveston Bay seafood harvest, and blue crab is a popular seafood species found along the Gulf and Atlantic coasts. More blue crabs are commercially harvested in Galveston Bay than in any other Texas estuary, approximately one-third of the state total.

Galveston Bay produces more oysters than any single water body in the United States, and rivals the combined production of Louisiana and Washington.

Recreational activities include duck hunting, saltwater fishing, swimming, nature viewing, pleasure boating, camping, picnicking, and sightseeing. Ecotourism, or tourism that is based on nature rather than man-made attractions is the tourist industry’s most rapidly expanding sector. Birding has become a very popular outdoor activity along the Texas Coast. Chambers County is visited by tourists primarily for natural attractions such as bird watching at High Island or wildlife viewing at the Anahuac National Wildlife Refuge. There are many stops around Galveston Bay on the Great Texas Coastal Birding Trail, which links 500 miles of coastal bird viewing sites from Brownsville to Beaumont.