Water & Sediment Quality Data Portal

About the Data

Data Sources:
The Texas Commission on Environmental Quality (TCEQ) Surface Water Quality Monitoring Program (SWQM) and the Houston-Galveston Area Council (H-GAC) Clean Rivers Program collect water quality data for the Galveston Bay Estuary and surrounding watershed. The data are used by the TCEQ to assess the state of water quality in the region. Samples collected by the TCEQ programs are compared to state water quality standards. Bodies of water not meeting the water quality standards set for certain designated uses (such as aquatic life protection, contact recreation, and oyster waters) are listed on the Texas list of impaired waters, also known as the Texas 303(d) List (named after Section 303(d) of the U.S. Clean Water Act). Water bodies on the Texas 303(d) List are subject to special studies known as Total Maximum Daily Load (TMDL) studies. A number of water bodies in the Houston-Galveston area on the State of Texas 303(d) List of Impaired Waters. Many of those are the subject of TMDL studies.

Parameter Descriptions: Data describing six types of water and sediment quality parameters can be accessed via the Galveston Bay Water and Sediment Quality Data Portal:

Water Quality:

• Conventional parameters (temperature, salinity, pH, etc.)
• Nutrients (ammonia, nitrate-nitrite, total phosphorus, etc.)
• Pathogens (fecal coliform bacteria, E. coli, Enterococci) 

Sediment Quality:

• Industrial organics (naphthalene, PCBs, etc.)
• Organic pesticides (chlordane, DDT, dieldrin, lindane)
• Heavy metals (Arsenic, cadmium, lead, mercury, etc.) 

Conventional parameters include those that are monitored to provide a general physical characterization of the water column and substrate. These parameters directly and indirectly reflect the chemical, physical and biological processes taking place in the estuary and associated tributaries.

Nutrients are essential for biological productivity, supporting the primary production of the estuarine food web. However, excess concentrations of nutrients can have negative effects such as eutrophication (over enrichment) of a waterbody which can lead to episodes of low dissolved oxygen levels and fish kills. Concentrations of nutrients are often associated with non-point source runoff (rainfall runoff from land) and in turn affect other water quality parameters such as dissolved oxygen, chlorophyll-a (an indicator of phytoplankton abundance), and pheophytin-a (the breakdown product of chlorophyll-a). Sources of nutrients include over-application of fertilizer on yards and agricultural fields and atmospheric deposition.

Human pathogens are assessed using the following parameters: fecal coliform bacteria, Enterococci (used in saltwater), and E. coli (used in freshwater). Although they are not usually harmful themselves, high concentrations of these parameters may indicate the presence of raw sewage or animal waste in water. They may also be evidence of harmful pathogens, viruses or bacteria that can cause illness in humans. Fecal coliform bacteria were the parameter of choice until 2000, at which time Enterococci and E. coli were incorporated into the sampling methodology.

Since the changes to bacterial indicators were instituted only recently by federal and state agencies, fecal coliform is still the bacteriological indicator most widely used to test recreational waters (waters used for boating, swimming, and fishing). Fecal coliform is also approved as an indicator by the U.S. Food and Drug Administration's National Shellfish Sanitation Program (NSSP) for classifying shellfish harvest waters. Sources of human pathogens to surface waters include wastewater treatment plants, septic systems, animal waste, and storm runoff. Pathogens can remain in an estuary for a long period of time; surviving for weeks in the sediment to be resuspended in the water column during a storm or other event that disturbs the sediment.

Toxic contaminants in sediments, including heavy metals, organic pesticides, and industrial organic compounds (e.g. PCBs), have the potential to affect all levels of the food chain. Therefore, it is important to evaluate the sediment concentrations to determine if levels of toxic contaminants are increasing or decreasing over time. Unfortunately, there is a general lack of data for these parameters in many areas of Galveston Bay and its tributaries. The exception is the Houston Ship Channel, which is the subject of much of the toxics in sediment sampling due to the presence of numerous industrial facilities.

View a list of selected state water quality criteria. These numbers provide a level of comparison against which the water and sediment quality data can be compared.