How's the Water?

Whether it is swimming, shipping, fishing, industry, or tourism, water is integral to the way of life for the 6.5 million people living in the Houston-Galveston region. With over 16,000 miles of streams and shorelines, water is all around us. The water that flows through our ditches, creeks, streams, bayous, and rivers feed into one of the nation’s most productive estuaries, Galveston Bay, before entering the Gulf of Mexico. These waters fuel our economy, bringing in billions of dollars and providing tens of thousands of jobs. Over 6.5 million people share these resources, and with another 3.8 million people expected to move to the region over the next 20 years, the strain put on these water resources will continue to rise.

The 2020 Basin Highlights Report provides watershed characterizations for several stream segments within the region. This report characterizes the Little White Oak Bayou (Segment 1013A), Clear Creek Tidal (Segment 1101), Clear Creek Above Tidal (Segment 1102), Mustang Bayou (Segment 2432A), and Halls Bayou (Segment 2432C) watersheds. The watershed characterizations identify:

• Specific water quality issues and trends;

• Sources of point and nonpoint source pollution;

• Current strategies and plans to reduce pollution within these watersheds; and

• Current and potential stakeholders within these watersheds.

The Houston-Galveston Area Council’s (H-GAC) Clean River Program is charged with conducting water quality monitoring and assessment to determine the health of water bodies throughout the region. H-GAC’s Clean Rivers Program does this through a coordinated effort with local partners and the Texas Commission on Environmental Quality (TCEQ). In addition to analyzing monitoring data, H-GAC assesses factors and activities affecting water quality. Through an extensive public education and outreach program, H-GAC provides information on regional water quality and recommendations on what individuals, industry, and local governments can do to preserve and make improvements to local waterways. Data acquired through the Clean Rivers Program provides support for all watershed-based activities in the region.

The numbers represent the percent of the total segment length that is impaired or of concern for each parameter. Cells without numbers (blanks) represent stream segments that are currently meeting state standards but may be improving or degrading for each parameter.

All ammonia, nitrate, and total phosphorus samples collected in Little White Oak Bayou (1013A_01) showed no concerns for exceeding the established nutrient screening criteria for that waterway (Table 7).

Potential sources of bacteria in the Little White Oak Bayou watershed include sanitary sewer overflows and nonpoint sources.

Sanitary Sewer Overflows

Although there are no regulated wastewater treatment facilities within the watershed, the area is almost entirely serviced by centralized sewer. As the transmission lines of these wastewater collection systems age, they are prone to failure, resulting in sanitary sewer overflows.

Based on sampling conducted as part of H-GAC’s special study “Top Five/Least Five” Project, at least one sanitary sewer overflow source, a failing junction box, was identified and reported to the City of Houston for repair.

Onsite Sewage Facilities

On-Site Sewage Facilities are found primarily in the upper reach of the watershed but can be found scattered throughout. Only 6 of these on-site facilities have been permitted and installed in this watershed since 1989. There are an unknown number of on-site facilities that were installed prior to permitting requirements as well as prior to sanitary sewer services being provided to some areas of the watershed. Because of the age of the systems present, and the likelihood that they are conventional septic systems instead of aerobic systems, they are prone to failure.

Other Nonpoint Sources

Other potential sources of pollution in this watershed include runoff during storm events. Runoff from junk yards and small paddocks/lots supporting a few animals are found scattered throughout the watershed. Chickens are also raised by a large number of homeowners throughout the watershed, with a maximum of 30 per household allowed by the City of Houston. Although rare in such an urbanized area, feral hogs have access to the area through the riparian corridor. Conditions created by the paddocks for chickens may create areas that are attractive to and conducive for infiltration by feral hogs.

Potential stakeholders include:

• City of Houston Public Works
• City of Houston Health Department
• City of Houston Parks and Recreation Department
• Harris County Pollution Control Services
• Harris County Flood Control District
• Houston Parks Board
• Environmental and Conservancy Organizations, such as Bayou Preservation Association
• Community Groups, such as the White Oak Bayou Association
• TCEQ Region 12
• The Bacteria Implementation Group (BIG) Members
• Houston City Council Members (specifically District H)
• Greater Northside Management District
• Citizen Groups, such as the Texas Master Naturalists
• Homeowner Associations
• Industry

The annual River, Lakes, Bays ‘N Bayous Trash Bash has a clean-up site at Moody Park which is immediately downstream of the Clean Rivers Program monitoring site at Trimble Street. Every year, hundreds of volunteers fill several dumpsters with trash collected from the stream, the banks and shoreline trees. Unfortunately, due to the close proximity to major highways and roadways, large amounts of litter and trash are carried by stormwater directly to areas adjacent to the bayou. It takes only a few rain events with medium to high flows for the area to be inundated with litter and trash. Unfortunately, due to closures and social-distancing requirements related to the COVID-19 pandemic, the Rivers, Lakes, Bays ‘N Bayous Trash Bash was cancelled for 2020.

Little White Oak Bayou was one of 10 waterbodies included in the “Top Five/Least Five” special study conducted by H-GAC from March 2016 through February 2017. Targeted monitoring was conducted to identify and eliminate sources of bacteria pollution. Four dry weather flows were identified as having high levels of bacteria. All four sources were turned over to the City of Houston for further investigation and remediation. Three of the four sources were remediated. The fourth source was from a failing junction box which is part of the sanitary sewer collection system. It was placed on a list of major city projects that will include significant engineering and reconstruction to eliminate.

AU 1013A_01 is listed in the 2018 Integrated Report as having depressed DO. To determine compliance with aquatic life use designations, TCEQ requires a minimum of two biological monitoring events be conducted, with one event completed during the index period and one event during the critical period. One biological monitoring event was conducted on Little White Oak Bayou at Trimble Street on June 28, 2017, during the index period. A second event, which would have been conducted during the critical period, was not collected due to safety concerns of the field crew and confirmation of impairments/concerns during the first event. Results from H-GAC’s subcontractor suggested the designated ALU rating of intermediate for nekton was not supported during their investigation. The subcontractor’s results suggest that the intermediate ALU rating was met for the microbenthic community, physical habitat and 24-hour DO during the index period. However, since two events are required by TCEQ to determine compliance, a final determination could not be made.

• Address bacteria and various other concerns through stakeholder involvement and best management practices
• Continue to analyze sanitary sewer overflow data from regulated dischargers and present results to TCEQ, wastewater permittees, local governments/utility districts, and stakeholders
• Support programs to assist homeowners with on-site sewage facilities, particularly those pre-dating permitting requirements, to connect to centralized sewer collection systems
• Continue collecting water quality data and expand monitoring efforts to support actions associated with the Total Maximum Daily Load program
• Pursue new local partners to collect additional data to help better isolate problem areas
• Support programs to educate homeowners on proper management of animal wastes, including those from pets and livestock
• Support programs to responsibly eliminate feral hog populations in the watershed
• Consult stakeholders to identify illegal dumping sites and improve signage and/or cameras, if needed

Other Nonpoint Sources

Landscaping related to residential developments, golf courses, etc., may be an important source of elevated bacteria and nutrients within certain areas of the watershed, particularly Magnolia Creek. Pet waste may be a significant contributor to bacteria levels, particularly in the heavily populated areas of the watershed. Hobby farms, supporting a small number of animals, are also common in the upper reach of Chigger and Robinson Creeks which would be another potential source of bacteria and nutrients.

Potential stakeholders include:

• City of Friendswood
• City of League City
• City of Nassau Bay
• City of Webster
• Galveston Bay Foundation
• Galveston County
• Gulf Coast Waste Disposal Authority
• Harris County Commissioner Precinct 1
• Harris County Commissioner Precinct 2
• TCEQ Region 12 Office
• TCEQ Galveston Bay Estuary Program
• Texas Community Watershed Partners
• Texas State Soil and Water Conservation Board
• The Bacteria Implementation Group (BIG) Members
• Environmental and Conservancy Groups
• Citizen Groups, such as the Texas Master Naturalists
• Community Groups
• Homeowner Associations
• Drainage Districts
• Utility Districts
• Industry

H-GAC has been tasked by the TCEQ to implement a basin-wide approach for addressing bacterial impairments for the San Jacinto-Brazos Coastal Basin which includes Clear Creek. Development for the basin-wide Total Maximum Daily Load began in September 2015 and resulted in a final Basin 11 Summary Report that summarized basin characteristics, water quality impairments, potential bacteria sources, and recommendations for bacterial reduction. This segment is also part of the geographic area for the Bacteria Implementation Group (BIG) Total Maximum Daily Load.

H-GAC will develop a watershed protection plan for Clear Creek. This project is scheduled to begin in September 2020.

• Address bacteria and various other concerns through stakeholder involvement and best management practices
• Continue to work with the BIG to implement recommendations for bacteria reduction
• Continue to analyze Discharge Monitoring Report data and present results to TCEQ, wastewater permittees, local governments/utility districts, and stakeholders
• Improve compliance and enforcement of existing stormwater quality permits and improve stormwater controls in new developments
• Support public education programs to inform business and homeowners on appropriate disposal of fats, oil, and grease
• Support programs that oversee the maintenance, repair, and replacement of on-site sewage facilities
• Continue collecting water quality data and expand monitoring efforts to support actions associated with the Total Maximum Daily Load program and future watershed protection plan development
• Pursue new local partners to collect additional data to help better isolate problem areas
• Expand volunteer monitoring with Texas Stream Team in areas without professional monitoring
• Implement YardWise and Watersmart landscape practices
• Create and implement Water Quality Management Plans for individual agricultural properties
• Support public education on pet waste disposal
• Consult stakeholders to identify illegal dumping sites and improve signage and/or cameras, if needed

Livestock and Other Animal Sources

Although there has been rapid development in this watershed, there are still areas with livestock. Animal wastes, as well as application of fertilizers, may contribute to bacteria and nutrient issues within the watershed. Additionally, feral hogs may be an issue is some of the less urbanized areas.

Potential stakeholders include:

• City of Brookside Village
• City of Friendswood
• City of Houston
• City of Pearland
• Brazoria County
• Galveston County
• Fort Bend County
• Harris County Commissioner Precinct 1
• Environmental and Conservancy Groups, such as local Keep Texas Beautiful Affiliates
• TCEQ Region 12 Office
• TCEQ Galveston Bay Estuary Program
• Texas State Soil and Water Conservation Board
• The Bacteria Implementation Group (BIG) Members
• Texas AgriLife Extension Offices
• Citizen Groups, such as the Texas Master Naturalists
• Community Groups
• Homeowner Associations
• Drainage Districts
• Utility Districts
• Industry

H-GAC has been tasked by the TCEQ to implement a basin-wide approach for addressing bacterial impairments for the San Jacinto-Brazos Coastal Basin which includes Clear Creek. Development for the basin-wide TMDL began in September of 2015 and resulted in a final Basin 11 Summary Report that summarized basin characteristics, water quality impairments, potential bacteria sources, and recommendations for bacterial reduction. This segment is also part of the geographic area for the Bacteria Implementation Group (BIG) Total Maximum Daily Load.

H-GAC will develop a watershed protection plan for Clear Creek. This project is scheduled to begin in September 2020.

• Address bacteria and various other concerns through stakeholder involvement and best management practices
• Continue to work with the BIG to implement recommendations for bacteria reduction
• Continue to analyze Discharge Monitoring Report data and present results to TCEQ, wastewater permittees, local governments/utility districts, and stakeholders
• Improve compliance and enforcement of existing stormwater quality permits and improve stormwater controls in new developments
• Support public education programs to inform business and homeowners on appropriate disposal of fats, oil, and grease
• Support programs that oversee the maintenance, repair, and replacement of on-site sewage facilities
• Continue collecting water quality data and expand monitoring efforts to support actions associated with the TMDL program and future watershed protection plan development
• Pursue new local partners to collect additional data to help better isolate problem areas
• Expand volunteer monitoring with Texas Stream Team in areas without professional monitoring
• Implement YardWise and Watersmart landscape practices
• Create and implement Water Quality Management Plans for individual agricultural properties
• Support programs to responsibly eliminate feral hog populations in the watershed, particularly in the less urbanized areas in the western portion of the watershed
• Support public education on pet waste disposal
• Consult stakeholders to identify illegal dumping sites and improve signage and/or cameras, if needed

There are no nutrient concerns in Mustang, Persimmon, or New bayous. Figures 5 and 6 show nutrient parameter results in Mustang Bayou.

Livestock and Other Animal Sources

Pasture and grassland make up a sizable portion of the Mustang Bayou watershed, and much of this land is used for agricultural and livestock use. With this land use, animal wastes and fertilizer application can contribute to bacteria and nutrient concentrations in waterbodies. Due to the rural nature of the watershed, there are numerous areas that are suitable for feral hogs. Wastes from household pets (dogs and cats) are also a potential source of bacteria.

Potential stakeholders include:

• Cities of Missouri City, Fresno, Manvel, Alvin, and Hillcrest
• Environmental and Conservancy Organizations, such as local Keep Texas Beautiful Affiliates
• Citizen Groups, such as the Texas Master Naturalists
• Texas AgriLife Extension Offices
• Texas State Soil and Water Conservation Board
• Texas Parks and Wildlife
• Homeowner Associations
• Drainage Districts
• Utility Districts
• Industry

A Total Maximum Daily Load for bacteria is being developed.

• Address bacteria and various other concerns through stakeholder involvement and best management practices
• Continue to analyze Discharge Monitoring Report data and present results to TCEQ, wastewater permittees, local governments/utility districts, and stakeholders
• Support public education programs to inform business and homeowners on appropriate disposal of fats, oil, and grease
• Support programs that oversee the maintenance, repair, and replacement of on-site sewage facilities
• Create and implement Water Quality Management Plans for individual agricultural properties
• Continue collecting water quality data and expand monitoring efforts to support actions associated with the Total Maximum Daily Load program
• Pursue new local partners to collect additional data to help better isolate problem areas
• Expand volunteer monitoring with Texas Stream Team in areas without professional monitoring
• Support programs to responsibly eliminate feral hog populations in the watershed
• Consult stakeholders to identify illegal dumping sites and improve signage and/or cameras, if needed

There are no nutrient concerns for ammonia-nitrogen, nitrate-nitrogen, total phosphorus, or chlorophyll-a for Halls Bayou Tidal or Willow Bayou identified in the 2018 Integrated Report.

Figure 3 shows results of grab samples for nitrate-N for Halls Bayou Tidal from 2004 – 2019. Numerous data points are reported at the limit of quantitation, so the result would be reported as a “less than” value (i.e., <0.01 mg/L). The trend appears to be decreasing but is being influenced by the lower limit of quantitation used for analysis between 2013 and 2016, which is bringing the trend down.

Figure 4 shows grab sample results for total phosphorus for Willow Bayou from 2004 to 2019. An increasing trend is observed; however, most results still remain under the screening level.

Additional Parameters

In reviewing data for Halls Bayou Tidal, a decrease in results for chloride (Figure 5), sulfate (Figure 6), and specific conductance (Figure 7) was noticed, beginning around 2014. The cause of these decreases is not known but may be related to flood and heavy rainfall events. Further examination may be warranted.

Livestock and Other Animal Sources

Much of the watershed land cover consists of cultivated crops, pasture, and grassland areas. Agricultural activities and livestock are common in the watershed. These activities can impact water quality through animal wastes and the application of fertilizers. The land use and lack of development in the segment is also conducive for feral hogs. In the more populated areas, household pet waste may contribute to bacteria in the waterways.

Potential stakeholders include:

• Brazoria County
• Galveston County
• Environmental and Conservancy Groups, such as local Keep Texas Beautiful Affiliates
• TCEQ Region 12 Office
• TCEQ Galveston Bay Estuary Program
• Texas State Soil and Water Conservation Board
• Texas AgriLife Extension Offices
• Citizen Groups, such as the Texas Master Naturalists
• Community Groups
• Homeowner Associations
• Drainage Districts
• Utility Districts

Total Maximum Daily Loads for bacteria are being developed for Halls Bayou Tidal (2432C) and Willow Bayou (2432B). Both water bodies fail to meet the standard for primary contact recreation and are listed as impaired in the 2018 Integrated Report.

• Address bacteria and various other concerns through stakeholder involvement and best management practices
• Support programs that oversee the maintenance, repair, and replacement of on-site sewage facilities
• Create and implement Water Quality Management Plans for individual agricultural properties
• Continue collecting water quality data and expand monitoring efforts to support actions associated with the TMDL program
• Pursue new local partners to collect additional data to help better isolate problem areas
• Expand volunteer monitoring with Texas Stream Team in areas without professional monitoring
• Support programs to responsibly eliminate feral hog populations in the watershed
• Consult stakeholders to identify illegal dumping sites and improve signage and/or cameras, if needed

The Water Quality Technical Primer is provided as an overview of general water quality terminology. In combination with the Glossary, the Technical Primer provides background and defines terminologies and methodologies used to acquire, analyze, and report the data that is presented in the Basin Highlights Report.

The Clean Water Act establishes the basic structure for regulating pollutant discharges, pollutant loadings in water, and regulating surface water quality standards. The goal of the Clean Water Act is “to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters” (33 U.S.C. §1251(a)).

Amendments to The Clean Water Act in 1977:

• Established the basic structure for regulating pollutant discharges into the waters of the United States;

• Gave the US Environmental Protection Agency (EPA) the authority to implement pollution control programs such as setting wastewater standards for industry;

• Maintained existing requirements to set water quality standards for all contaminants in surface waters;

• Made it unlawful for any person to discharge any pollutant from a point source into navigable waters, unless a permit was obtained under its provisions;

• Funded the construction of sewage treatment plants under the construction grants program; and

• Recognized the need for planning to address the critical problems posed by nonpoint source pollution.

Pollution

The Texas Administrative Code defines pollution as “the alteration of the physical, thermal, chemical, or biological quantity of, or the contamination of, any water in the state that renders the water harmful, detrimental, or injurious to humans, animal life, vegetation, or property or to public health, safety, or welfare, or impairs the usefulness or the public enjoyment of the water for any lawful or reasonable purpose.”

There are two categories of pollution: Point Source and Nonpoint Source Pollution.

Point Source pollution is any source of pollution that is subject to regulation and is permitted. An example of a point source is a permitted wastewater treatment facility effluent discharge.

Nonpoint Source (NPS) pollution is any source that is not subject to regulation, that is diffuse and does not have a single point of origin, or is not introduced into a receiving stream from a specific outfall. NPS pollution typically results from land runoff, precipitation, atmospheric deposition, drainage, seepage, or hydrologic modification.

The Texas Surface Water Quality Standards (TSWQS) establish numerical and narrative goals to maintain the quality of streams, rivers, lakes, and bays throughout the state. Appendix A and Appendix D of the TSWQS establish the geographic boundaries and the appropriate standards for each body of water. The standards are developed to maintain the quality of surface waters. Standards ensure public health and enjoyment, protect aquatic life, and remain consistent with the sustainable economic development of the state. The Texas Commission on Environmental Quality (TCEQ) develops the TSWQS under the authorization of the U.S. Clean Water Act and Texas Water Code. The TSWQS are codified in Title 30, Chapter 307 of the Texas Administrative Code. The standards are approved by the EPA.

The TSWQS are designed to:

• designate the uses, or purposes, for which the state’s water bodies should be suitable;

• establish numerical and narrative goals for water quality throughout the state; and

• provide a basis on which TCEQ regulatory programs can establish reasonable methods to implement and attain the state’s goals for water quality.

The criteria adopted and incorporated into the standards are the allowable concentrations of pollutants in State, Territory, and authorized Tribal waters and are developed for the protection of aquatic life and human health. Impairments occur when water quality conditions do not meet the assigned uses or criteria as defined in the TSWQS.

A watershed is a defined geographic area that waterways flow through on the way to a common body of water. Basins are larger geographic areas generally containing one or more watersheds. A river basin is a collection of watersheds drained by a major river and tributaries. A coastal basin is a collection of watersheds adjacent to the coastline that water flows through on its way to the ocean. Typically, coastal basins are between and bound by two major river basins and a bay or other outlet to the ocean.

Watersheds can be broken down into even smaller drainage areas, which are referred to as sub-watersheds. For example, a sub-watershed could be defined as the drainage area of a small creek, stream, or portion of a stream that is part of the drainage area for a tributary, which is part of a major river drainage basin.

The term water body is used to refer to any mass of water. A water body can be contained in a lake or a bay, or flow, such as a river, creek, or bayou. The TCEQ divides water bodies in the state into distinct segments that generally represent natural watersheds and are intended to have similar chemical, physical, and hydrological characteristics. Each segment is assigned a four-digit code. The first two digits identify the river basin, and the last two digits identify the segment. Segments can be either classified or unclassified.

Classified Segments

A classified segment is a water body (or portion of a water body) that is individually defined in the TSWQS. Typically, classified segments are major waterways. Site specific numerical criteria are developed to evaluate the uses and overall water quality of a classified segment. The parameters evaluated include bacteria, nutrients, and dissolved oxygen.

Site-specific numerical criteria are developed to evaluate the uses and water quality of classified segments. These uses include aquatic life use and recreational use (discussed later in the primer). 

Unclassified Segments

Unclassified segments are often tributaries of classified segments. These segments are usually assessed based on the criteria of the classified segment into which they flow. However, some unclassified segments have been assigned specific water quality standards in the TSWQS. Unclassified segments are assigned the same four-digit code as the classified segment and a letter that is specific to that waterway.

Assessment Units (AUs)

For assessment purposes, each segment is subdivided into hydrologically-distinct units, or assessment units (AUs). AUs are the smallest geographic areas of a water body that can support a designated or site-specific use. A segment may have one or multiple AUs, depending on water quality conditions or flow in different sections of the water body. Each AU has the same four or five-digit code as the segment followed by an AU identifier (e.g., _01, _02, etc.). If there are multiple AUs, the assessment units will generally be in sequential order (e.g., 1007D_01, 1007D_02, etc.). Each AU is evaluated separately as part of the assessment.

For example, Sims Bayou Above Tidal is divided into three AUs. The red dots represent monitoring stations. Monitoring stations have been placed on the downstream and upstream ends of each AU in 1007D. The smaller tributaries, 1007A and 1007N, have one monitoring station close to the confluence with the parent stream 1007D.

As defined in the TSWQS, a water body can be assigned specific uses including aquatic life, public water supply, and contact recreation use. Designated uses typically have corresponding numeric criteria listed in the TSWQS. General criteria apply across the entire state, but if sufficient information is available for a specific water body, the site-specific standards may be developed.

Aquatic Life Use

Aquatic life use (ALU) is determined by the amount of dissolved oxygen and the abundance and diversity of species. Aquatic life use consists of five categories: minimal, limited, intermediate, high, and exceptional. In Texas, water bodies not specifically listed in Appendix A or D of the TSWQS are presumed to have a high aquatic life use and corresponding dissolved oxygen criteria. This use is assessed using 24-hour dissolved oxygen data along with nekton and macrobenthic invertebrate community evaluations.

Public Water Supply Use

Public water supply use includes an evaluation of chloride, sulfates, and total dissolved solids in the water body. Criteria for these parameters are set so that public water supplies are capable of treating and delivering water of acceptable quality.

Recreational Use

Recreational use refers to how safely a water body can support activities that involve the possibility of ingesting or coming into contact with water. If activities are likely to result in ingestion of water (swimming, diving, tubing, surfing, wading by children), bacteria concentrations need to be lower. The TSWQS protects human health by setting numeric criteria in a water body relative to the types of recreational activity occurring on that water body. Fecal indicator bacteria levels are measured to determine risk. Criteria area expressed as the number of bacteria per 100 milliliters (mL) of water [in terms of colony-forming units (CFU), most probable number (MPN), or other applicable reporting measures]. The presence of fecal indicator bacteria in waters suggests that human and animal wastes may be reaching the assessed waters. In freshwater, the indicator organism is Escherichia coli (E. coli). Enterococci bacteria are the indicator for tidal water bodies.

There are four categories of recreational use, which are based on the type and frequency of recreation. Primary contact recreation refers to activities such as swimming, diving, and waterskiing. These activities are presumed to have a high likelihood of ingesting water. Secondary Contact Recreation refers to activities that have limited body contact, such as wading, fishing, and canoeing. If such activities are occurring frequently, the designation is Secondary Contact Recreation 1. If the activities are less frequent due to physical characteristics such as steep banks or limited public access, the designation is Secondary Contact Recreation 2. A waterbody could be classified as supporting Noncontact Recreation if conditions are unsafe to engage in any activities in the water.

Primary contact recreation is the presumed recreational use in Texas water bodies unless there is evidence to show that the water body is not used for primary contact recreation. A Recreational Use Attainability Analysis (RUAA) is necessary to change the presumed use of a water body.

Surface Water Quality Monitoring (SWQM) Program

TCEQ’s Surface Water Quality Monitoring Program evaluates the physical, chemical, and biological characteristics to ensure that it is suitable for general or designated uses. Water quality is monitored and evaluated in relation to human health concerns, ecological conditions, and designated uses. Data collected under the SWQM program is utilized by the TCEQ to provide a basis for effective policies that promote the protection, restoration, and wise use of the state’s surface water.

Surface water samples are collected for assessment purposes following the methodologies outlined in TCEQ’s Surface Water Quality Monitoring Procedures Volume 1: Physical and Chemical Monitoring Methods (TCEQ Publication RG-415) (colloquially referred to as “SWQM Procedures”). The guidelines outlined in the SWQM Procedures manual document the methods and the quality assurance procedures that must be used to demonstrate that data collected by monitoring personnel across the state are of a known and adequate quality. All data collected by H-GAC and its partners are collected following SWQM procedures.

Water quality data, including data collected under SWQM and the Clean Rivers Program, are stored in the Surface Water Quality Monitoring Information System (SWQMIS). This database is used to enter, manage, track, and report on water quality-related data.

Coordinated Monitoring Schedule (CMS)

The Coordinated Monitoring Schedule (CMS) is the combined schedule for all surface water quality monitoring in Texas. Monitoring entities within a basin or region meet annually to establish and coordinate monitoring schedules as a way to ensure appropriate coverage, reduce duplication of effort, and better utilize available resources.

The CMS lists:

• monitoring stations

• collecting entities

• submitting entities

• monitoring type

• parameters

• monitoring frequency

The Coordinated Monitoring Schedule is available online at  cms.lcra.org .

Quality Assurance Project Plan (QAPP)

H-GAC’s Clean Rivers Program Quality Assurance Project Plan (QAPP) describes H-GAC’s quality assurance policies, management structure, and procedures used to implement the quality assurance requirements for the Clean Rivers Program. These policies and procedures are necessary to verify and validate data collected for the Clean Rivers Program. The QAPP is reviewed and approved by TCEQ to help ensure that all data generated are of known and documented quality, deemed acceptable for their intended use and that the data have been collected and managed in such a way as to guarantee its reliability. Only quality-assured data may be used for water quality assessments or other regulatory purposes. H-GAC’s current and previous QAPP documents are available on H-GAC’s website at  h-gac.com .

Monitoring Types

Monitoring activities may be divided into the following categories:

• Routine Monitoring

• Special-Study Monitoring

• Permit-Support Monitoring

• Systematic Monitoring

The type of monitoring conducted by the Clean Rivers Program is usually routine, meaning it is monitoring that is scheduled in advance without intentionally trying to target any certain environmental condition, with samples being collected regardless of the conditions encountered. Routine monitoring, at a minimum, includes field measurements [DO, pH, specific conductance, temperature], conventional chemical parameters (nutrients, chloride, sulfate), bacterial measurements (E. coli or enterococci), and flow measurements (if applicable for that water body). Please see the List of Parameters Appendix for a detailed description of each parameter.

Another monitoring type conducted by the Clean Rivers Program is biased monitoring (monitoring targeted to a season, time, or condition) measurements, such as 24-hour DO. In this procedure a data sonde (a water quality monitoring device that calculates and records field parameters) is deployed to measure DO every 15 minutes for 24 hours. After the deployment period, the data is analyzed, and the 24-hour average and absolute minimum are calculated. The DO average and absolute minimum are used to assign an ALU category to a water body. For example, exceptional aquatic life use has a 24-hour average of 6.0 mg/L and an absolute minimum of 4.0 mg/L.

The provisions of sections 305(b) and 303(d) of the Clean Waters Act require the TCEQ to provide the Texas Integrated Report for Clean Water Act Sections 305(b) and 303(d) (Integrated Report) to the EPA every two years. The report contains a list of water bodies evaluated, water bodies assessed by basin, impaired water bodies (303(d) List), water bodies of concern, water bodies either newly listed or removed from the 303(d) List, and other supporting information.

For the assessment, TCEQ evaluates data collected during a seven-year period. The timeframe is extended to 10 years (if needed) to attain the minimum number of data points needed for the assessment.

Each assessed water body is identified as:

• Fully Supporting: at least 10 data points (20 for bacteria) are available for an assessment, and the water body meets TSWQS or supports designated uses

• Of Concern: There are two levels of concern, CN and CS. CN means there is concern for near nonattainment of the TSWQS based on numeric criteria. A concern status of CN indicates that standards are not being met, but there is insufficient data to fully assess the water body. CS means that there is a concern for water quality based on screening levels. Screening levels are used when there is not a defied standard (as with nutrients) and are derived from statistical distributions of statewide water quality monitoring data, with the 85th percentile for each applicable parameter is used as the screening level criteria.

• Impaired – Data indicates that the water body does not meet standards. Impaired waterbodies are placed on the 303(d) List.

When a water body is determined to be impaired, several things must happen:

• The water body must be listed on the 303(d) List;

• An evaluation must be undertaken to determine what is preventing the water body from supporting its designated use(s) or if the use(s) are appropriate;

• Steps must be taken to either remedy the problem, collect additional data, or evaluate which uses are appropriate for the water body. These steps may include additional monitoring, development of a Total Maximum Daily Load (TMDL) or Watershed Protection Plan (WPP), or a review of the water quality standards.

After assessment, water bodies are placed into one of five categories (with subcategories). These categories indicate the water quality status of the water body.

If a previously assessed AU has insufficient data available during the assessment period for the most recent Integrated Report, this results in a carry-forward of the impairment listing from the previous report.

If sufficient data is available to determine that a waterbody is impaired and does not meet standards, a management measure can be utilized to address the impairment.

• A Total Maximum Daily Load (TMDL) is a method used to determine the amount (load) of a pollutant an impaired waterbody can receive daily and still meet water quality standards and designated uses. After a load is calculated for the pollutant sources, an implementation plan (I-Plan) is drafted by the waterbody’s stakeholders outlining management measures to be used to return the target pollutant to the calculated load. An I-Plan’s management measures are usually voluntary actions but can, if recommended by stakeholders, include regulatory actions.

• A Watershed Protection Plan (WPP) is a community and stakeholder driven framework that uses a holistic/watershed approach to address potential sources of impaired waterways. The plan is developed with community involvement, and the measures to reduce pollutants are voluntary.

• A Use Attainability Analysis (UAA) determines if the natural characteristics of a water body cannot attain the currently designated uses and/or criteria. Natural characteristics include temperature, pH, DO, diversity of aquatic organisms, amount of streamflow, and physical conditions such as depth. If there is a consensus among stakeholders and resource agencies that a presumed or designated use may not be appropriate for a water body, a UAA may be conducted to determine the most appropriate use(s).

• A Recreational Use Attainment Analysis (RUAA) is used to determines if contact recreation use occurs in a waterbody. A waterway may have physical characteristics or limited public access that would not warrant a contact recreation use designation.

The identification of long- and short-term trends is important to many stakeholders, and these trends are important components of the Houston-Galveston Area Council’s (H-GAC’s) work, particularly in relation to the evaluation and revision of regional monitoring efforts and priorities. H-GAC staff used several methods of analyses to characterize surface water quality in the H-GAC region. Trend analysis can identify cases where the value of a water quality parameter is changing over time. Statistical tests are performed to distinguish statistically significant trends from random and seasonal variation. While it might seem reasonable to use all the data available for these analyses, as the amount of data increases the likelihood of finding a statistically significant but unimportant trend also increases. To minimize this, H-GAC performed trend analysis on the most recent 15 years (June 2004–May 2019) of Texas Commission on Environmental Quality (TCEQ)-validated data to highlight recent trends in water quality in the region. Data from the most recent 7 years (2012 – 2019) were used to compare assessment results and to calculate geometric means.

All data management and statistical analysis were performed using Statistical Analysis System (SAS) version 9.3. Complete details of data selection, preparation, and analysis can be found in the SAS code, which is available upon request.

Data Selection and Processing

For analyses in this report, H-GAC staff selected water quality data collected between June 1, 2004, and May 31, 2019 from data downloaded from the Surface Water Quality Monitoring Information System (SWQMIS) on October 7, 2019. SWQMIS is a database that serves as the repository for surface water quality data for the state of Texas. All data used for these analyses were collected under a TCEQ-approved Quality Assurance Project Plan (QAPP). Qualified data (data added to SWQMIS with qualifier codes that identify quality, sampling, or other problems that may render the data unsuitable) were excluded from the download. All data for all stations in the H-GAC Clean Rivers Program region (in general, basins 9, 10, 11, 13, and 24) were combined.

Variables in each data-set were transformed as appropriate, and new variables were created to facilitate analysis and graphical display of results. In some cases, data from two or more STORET (method) codes were combined because the results obtained from each method can be considered equivalent. Any data collected at a depth greater than 0.3 meters, or not collected under a routine ambient monitoring program, were deleted.

Censored data (data reported as < [parameter limit of quantitation (LOQ)] were transformed to a value of one-half the parameter LOQ associated with the data, with some important exceptions. Because nutrient quantitation limits have been lowered over time, the presence of data censored at many different LOQs in the same dataset poses several problems. If the data for a given parameter are censored at values well above a later, lower LOQ value, trend analysis could suggest a trend where no real water quality trend is present. There is no ideal solution to this problem. Editing the censored data alone would limit, but not eliminate, false trends. In cases where some of the data reflected use of a lower LOQ than the current H-GAC Clean Rivers Program LOQ, values were transformed to one-half of the H-GAC Clean Rivers Program to minimize the identification of trends caused by changing analytical methods. H-GAC does not believe the impact from this transformation is significant. The impact of this analysis would be most pronounced for parameter trends typically found at concentrations at or near the quantitation limit in that specific water body.

Parameters selected for analysis are listed in Table 1.

Data Selection for Trend Analysis

H-GAC staff performed segment-level trend analysis on a 15-year data series (if available) from all data in the segment. Trends were also evaluated at the assessment unit (AU) level, and graphs showing results from individual stations within each AU were produced for review.

Trend analysis methodology

The first stage of trend analysis looked for temporal patterns for both segments and AUs. To identify these patterns, nonparametric correlation analysis (Kendall’s tau-b) of the parameter value with the sample collection date was used to identify correlations that were significant at p <0.05. These potential trends were then evaluated with up to four other methods. Simple linear regression of the natural log of the parameter value on the time variable was performed for all data in the subset selected by H-GAC for trend analysis. Flow-adjusted trends were obtained through correlation of residuals from LOESS (locally-weighted least squares) regression in cases where instantaneous flow data were available. If there were no temporal gaps in the time-series (missing years, consistently missing seasons), seasonal Kendall/Sen Slope estimation/Theil regression was run. If more than 15 percent of the data were censored at the analytical limit of quantitation, survival analysis (Tobit analysis in SAS PROC LIFEREG) was performed.

Plots of selected statistically-significant trends were produced for segments and AUs in each of the watersheds selected for this report. Each graph includes an inset showing the results of multiple trend analyses. If the trend is described as Increasing or Decreasing the calculated p-value is below the threshold of 0.05 selected by H-GAC. Trends identified as Stable have a calculated p-value greater than 0.05. When evaluating the results of several trend analyses of a given parameter, H-GAC placed the most weight on the Kendall correlation because nonparametric methods are insensitive to outliers in the time series. However, if Kendall correlation differed from the results of seasonal trend analysis or flow-weighted analysis, the data were further evaluated. If no flow data were available, the flow-adjusted trend appears as Not Calculated (indicating no flow data is available) or Insufficient Data (indicating only one flow value exists and a correlation could not be calculated). If the seasonal Kendall/Sen Slope trend was not calculated due to gaps (missing seasons) in the time series, the seasonal Kendall trend appears as Not Calculated. Survival analysis was only applied in those cases where the amount of censored data could bias the results of the other methods. H-GAC set the threshold at 15 percent or more censored data. If fewer than 15 percent of the data were censored, survival analysis was not performed, and the trend appears as Not Applicable on graphs.

Trend analysis for the Regional Water Quality Summary

In 2015, H-GAC staff compiled a subset of stations in classified segments believed to be most representative of segment water quality by selecting one to three stations that were statistically representative of a given parameter in a given segment. Means and standard deviations of parameter values are calculated for each station, and those stations with means and standard deviations closest to the overall mean and standard deviation for the segment and parameter combination were selected. Preference was given to stations where stream flow was measured, and final selections were reviewed for reasonableness. In most cases, the station or stations at the most downstream location of the segment was the most statistically representative. Selection relied on SAS procedures PROC MEANS and PROC RANK. The same subset of stations has been used since 2015 to allow consistent comparisons across regional water quality summaries created for different years.

A conservative trend analysis was performed using seven years of recent data (June 1, 2012 – May 31, 2019) at the selected representative monitoring stations in the classified portion of each watershed to detect trends at the watershed level for the H-GAC Regional Water Quality Summary. Trends were identified by nonparametric correlation analysis and simple linear regression. Because nonparametric methods are less sensitive to extreme values in the data than parametric techniques like linear regression, trends that were suggested by linear regression analysis alone were not included in the chart.

Trends (for the “ Frog Chart ” analysis) were considered statistically significant if the p-value was below 0.05, which is the standard significance level used in most applications. 

A Note on Statistical Significance

H-GAC feels that selecting all results with p-values ≤0.10 produces too many real, but unimportant, trends. In part, this is due to the large amount of data collected for our region – the more data one analyzes, the more likely it is that one will find a result – and identify a “trend” – that is statistically different from randomness (“no trend”). For example. 0.0545 rounds to 0.55, which in “arithmetic rounding’ becomes 0.06 when expressed as one significant figure.

Moving Geometric Mean Plots

In addition to trend analysis, H-GAC created plots of seven-year geometric means for indicator bacteria for each segment. These are a type of moving- or rolling-average plot, and they are constructed by calculating the geometric mean of all data collected up to seven years before a given sample was collected and plotting it (on the y-axis) against the collection date (on the x axis) of the last sample in the series. A smoothed line (penalized B-spline) is fitted to the time series. One can assess the change in bacterial density over time from this sort of plot more easily than from a simple plot of density versus time. These plots are more meaningful for segments with historical bacteria data than for segments recently added to monitoring schedules (typically unclassified segments).

Watershed Characterizations

H-GAC used SAS to produce tables showing impairments and concerns for each AU, monitoring stations in each AU and segment, and a variety of other summary data to aid in the characterization of water quality issues in each watershed. In most cases, the source of the tabulated information was TCEQ (Integrated Reports and assessment results, the Coordinated Monitoring Schedule, station inventory reports, AU and segment GIS shapefiles).

ALU - Aquatic Life Use

AU - Assessment Unit

BIG - Bacteria Implementation Group

BMP -  Best Management Practices

CFS -  Cubic feet per second

CFU -  Colony-forming Unit

CMS -  Coordinated Monitoring Schedule

CN -  Concern for near-nonattainment

CRP -  Clean Rivers Program

CS -  Concern for screening levels

CWA -  Clean Water Act

DMR -  Discharge Monitoring Report

DO -  Dissolved oxygen

EIH -  Environmental Institute of Houston, University of Houston-Clear Lake

EPA -  U.S. Environmental Protection Agency

FROG -  Fats, rags, oils, and grease

FS -  Fully-supporting designated use

FY -  Fiscal year

HCFCD -  Harris County Flood Control District

H-GAC -  Houston-Galveston Area Council

I-Plan -  Implementation Plan

IR -  Texas Integrated Report for Clean Water Act Sections 305(b) and 303(d)

km -  kilometer

L -  liter

LOESS -  Locally-Weighted Least Squares Plot

LOQ -  Limit of Quantitation

mg -  milligram

mg/L -  milligram per liter

MGD -  Millions of gallons per day

mi -  mile

mL -  milliliter

MPN -  Most Probably Number

MS4 -  Municipal Separate Storm Sewer System

NC -  No concern

NCR -  Non-contact recreation

NPDES -  National Pollutant Discharge Elimination System

NPS -  Nonpoint source pollution

NS -  Nonsupport for designated use

OSSF -  On-site sewage facility

PCB -  Polychlorinated biphenyl

PCR -  Primary contact recreation

QAPP  - Quality Assurance Project Plan

RUAA -  Recreational use attainment analysis

SAS -  Statistical Analysis System

SEP -  Supplemental Environmental Project

SJRA -  San Jacinto River Authority

SSO -  Sanitary Sewer Overflow

SWQM -  Surface Water Quality Monitoring

SWQMIS -  Surface Water Quality Monitoring Information System

TCEQ -  Texas Commission on Environmental Quality

TDS -  Total dissolved solids

TDSHS -  Texas Department of State Health Services

TKN -  Total Kjeldahl Nitrogen

TMDL -  Total Maximum Daily Load

TPDES -  Texas Pollutant Discharge Elimination System

TRIES -  Texas Research Institute for Environmental Studies

TSS -  Total suspended solids

TSSWCB -  Texas State Soil and Water Conservation Board

TSWQS -  Texas Surface Water Quality Standards

UAA -  Use attainability analysis

USGS -  U.S. Geological Survey

WPP -  Watershed Protection Plan

WWTF -  Wastewater treatment facility

Algae - Plants that lack true roots, stems and leaves. For the physical assessment described in this document, algae consist of nonvascular plants that attach to rocks and debris or float freely in the water. Such plants may be green, blue-green, or olive-green and slimy to the touch. They usually have a coarse filamentous structure.

Ambient - The existing water quality in a particular water body.

Ammonia-Nitrogen (NH3-) - Ammonia, naturally occurring in surface and wastewaters, is produced by the breakdown of compounds containing organic nitrogen.

Aquatic Life Use (ALU) – A designation assigned to an individual water body segment based upon the potential to support aquatic life.

Assessment Unit (AU) – The smallest geographic areas of a water body that can support a designated or site-specific use.

Attainable Use - A use that can be reasonably achieved by a water body in accordance with its physical, biological and chemical characteristics whether it is currently meeting that use or not. Guidelines for the determination and review of attainable uses are provided in the standards implementation procedures. The designated use, existing use, or presumed use of a water body may not necessarily be the attainable use.

Basin – Large geographic areas generally containing one or more watersheds.

Benthos - Aquatic bottom-dwelling organisms including worms, leeches, snails, flatworms, burrowing mayflies and clams.

Best Management Practices - Schedules of activities, maintenance procedures, and other management practices to prevent or reduce the pollution of water to the maximum extent practicable. Best management practices include treatment requirements, operating procedures, and practices to control plant site runoff, spillage or leaks, sludge or waste disposal, or drainage from raw material storage.

Bloom - The accelerated growth of algae and/or higher aquatic plants in a body of water. Bloom is often related to pollutants that increase the rate of growth.

Channelization - Straightening and deepening streams so water will move faster. A method of flood control that disturbs fish and wildlife habitats and can interfere with a water body’s ability to assimilate waste.

Chloride (Cl-1) - One of the major inorganic ions in water and wastewater. Concentrations can be increased by industrial processes. High chloride concentrations can affect metallic objects and growing plants.

Chlorophyll a - A photosynthetic pigment found in all green plants. The concentration of chlorophyll a is used to estimate phytoplankton biomass (all of the phytoplankton in a given area) in surface water.

Classified - Refers to a water body that is listed and described in Appendix A or Appendix C of the Texas Surface Water Quality Standards.

Coastal Basin – A collection of watersheds adjacent to the coastline that water flows through on its way to the ocean.

Conductivity - A measure of the carrying capacity for electrical current, in mhos/cm, of 1 cm3 of water at 25°C. Dissolved substances in water dissociate into ions with the ability to conduct electrical current. Conductivity is a measure of how salty the water is. Salty water has high conductivity.

Contact Recreation - Recreational activities involving a significant risk of ingestion of water; including wading by children, swimming, water skiing, diving, and surfing. See also noncontact recreation.

Conventional Parameters - A list of basic parameters that require laboratory analyses. The parameters frequently include, but are not limited to, solids (TSS, TDS, VSS), nutrients (nitrogen and phosphorus compounds), chlorides, sulfates, hardness, and TOC.

Criteria - Water-quality conditions that are to be met in order to support and protect desired uses.

Designated Use - A use that is assigned to specific water bodies in Appendix A or in Appendix D of the Texas Surface Water Quality Standards. Typical uses that may be designated for specific water bodies include domestic water supply, categories of aquatic-life use, kinds of recreation, and aquifer protection.

Dioxin - A family of polychlorinated chemicals found in waste from the paper bleaching processes and the combustion of chlorinated compounds. It is considered carcinogenic and can disrupt the reproductive and immune systems in humans.

Dissolved Oxygen - The oxygen freely available in water. Dissolved oxygen is vital to fish and other aquatic life and for the prevention of odors. Traditionally, the level of dissolved oxygen has been accepted as the single most important indicator of a water body’s ability to support desirable aquatic life.

Dissolved Oxygen (DO) Measurements, 24-hour – The measurement of dissolved oxygen over a 24-hour period using deployed, unattended, automated equipment preset to record and store field measurements over one 24-hour period. These measurements are used to assess Aquatic Life Use.

Effluent - Wastewater (treated or untreated) that flows out of a treatment plant or industrial outfall (point source) prior to entering a water body.

Enterococci - A subgroup of fecal streptococcal bacteria (mainly Streptococcus faecalis and Streptococcus faecium) found in the intestinal tracts and feces of warm-blooded animals. It is used as an indicator of the potential presence of pathogens.

Escherichia coli (E. coli) – E. coli is a member of the total coliform group of bacteria found in feces. It indicates fecal contamination and possible presence of enteric pathogens (viral, protozoan, and bacterial pathogens of the gastrointestinal route).

Estuary - Regions of interaction between rivers and near shore ocean waters, where tidal action and river flow create a mixing of fresh and salt water.

Fecal Coliform - A subset of the coliform bacteria group that is found in the intestinal tracts and feces of warm-blooded animals. Heat-tolerant bacteria from other sources can sometimes be included. It is used as an indicator of the potential presence of pathogens.

Field Parameters - A list of basic tests generally collected in the field using equipment and meters. The list also includes visual observations.

Fully Supporting – The water body meets TSWQS or supports its designated uses.

Habitat - The area in which an organism lives.

Impaired – A designation for an associated use (aquatic life, contact recreation, etc.) where a water quality standard is not attained.

Impoundment - A body of water confined by a dam, dike, floodgate, or other barrier.

Indicator Organism - An organism, species or community that indicates the presence of a certain environmental condition or conditions.

Limit of Quantitation (LOQ) – The lowest concentration of a substance that can be accurately measured under specific conditions.

LOESS Plot - a graph that shows the relationship of two variables (measurements or parameter values) made using a technique that calculates the slope of the plotted line at different time periods (locally weighted least-squares regression), producing a line that usually shows inflections (change points) rather than a straight line that best fits all points. LOESS is not really an acronym, and can be thought of as “LOcal regrESSion.”

Macrobenthic Invertebrate - Aquatic bottom-dwelling fauna. Common types are flat worms, leeches, snails, and various insect species.

Monitoring – The process of sampling and analyzing water quality parameters over time.

Municipal Separate Storm Sewer System (MS4) – A conveyance (or system of conveyances) that is owned by a state, city, town, village, or other public entity that discharges to waters of the U.S., is designed to collect or convey stormwater (e.g., storm drains, pipes, ditches), is not a combined sewer, and is not part of a sewage treatment plant or publicly owned treatment works.

Nekton - Free-swimming organisms (for example, fish, insects).

Nitrate-Nitrogen (NO3-N) - A compound containing nitrogen that can exist as a dissolved solid in water. Excessive amounts can have harmful effects on humans and animals (>10 mg/L).

Nitrite-Nitrogen (NO2-N) - An intermediate oxidation state in the nitrification process (ammonia, nitrite, and nitrate).

Noncontact Recreation - Aquatic recreational pursuits not involving a significant risk of water ingestion and limited body contact incidental to shoreline activity; including fishing, and commercial and recreational boating. See also contact recreation.

Nonpoint Source (NPS) Pollution - A pollution source that is not subject to regulation, that is diffuse and does not have a single point of origin, or is not introduced into a receiving stream from a specific outfall. NPS pollution typically results from land runoff, precipitation, atmospheric deposition, drainage, seepage, or hydrologic modification.

Nutrient - Any substance used by living things to promote growth. The term is generally applied to nitrogen and phosphorus in water and wastewater, but is also applied to other essential and trace elements.

Outfall - A designated point of effluent discharge.

Oyster Waters - Waters producing edible species of clams, oysters, or mussels.

pH - The hydrogen-ion activity of water caused by the breakdown of water molecules and presence of dissolved acids and bases.

Phosphorus - A nutrient that is essential to the growth of organisms. It can be the nutrient that limits the primary productivity of water. In excessive amounts from wastewater, agricultural drainage, and certain industrial waste it also contributes to the eutrophication (the natural aging progression) of lakes and other water bodies.

Pollution - The alteration of the physical, thermal, chemical, or biological quality of, or the contamination of, any water that renders it harmful, detrimental, or injurious to humans, animal life, vegetation, property, or the public health, safety, or welfare. Pollution may impair the usefulness or the public enjoyment of the water for any lawful or reasonable purpose.

Point Source pollution - Any source of pollution that is subject to regulation and is permitted. An example of a point source is a permitted wastewater treatment facility effluent discharge.

Polychlorinated Biphenyls (PCBs) - A class of organic compounds used in dielectric fluids in transformers, capacitors, and coolants. PCBs are highly toxic and are associated with endocrine disruption and neural toxicity in humans.

Public Water Supply Use - A water body designated to provide water to a public water system.

Quality Assurance Project Plan (QAPP) – A written document outlining the procedures a monitoring project will use to ensure the data it collects and analyzes meets project requirements.

Recreational Use Attainment Analysis (RUAA) – A UAA that determines is designed to determine if contact recreation is an appropriate use of a water body.

Reservoir - Any natural or artificial holding area used to store, regulate, or control water.

River Basin - The land area drained by a river and its tributaries.

Routine Monitoring – Monitoring that is scheduled in advance without intentionally trying to target a certain environmental condition. Routine monitoring typically consists of field measurements, conventional chemical parameters, bacteria, and flow measurements.

Runoff - The part of precipitation or irrigation water that runs off land into streams and other surface water.

Screening Level – Established targets (instream concentrations) for parameters that establish targets that can be directly compared to monitoring data. Screening levels are derived from long-term monitoring data or published levels of concern.

Sediment - Particles and/or clumps of particles of sand, clay, silt, and plant or animal matter carried in water and deposited in reservoirs and slow-moving areas of streams and rivers.

Segment - A water body or portion of a water body that is individually defined and classified in the Texas Surface Water Quality Standards. A segment is intended to have relatively homogeneous chemical, physical, and hydrological characteristics. A segment provides a basic unit for assigning site-specific standards and for applying water quality management programs. Classified segments may include streams, rivers, bays, estuaries, wetlands, lakes, and reservoirs.

Sonde – A multi-parameter water quality monitoring device that calculates and records field parameters.

Standards - The designation of water bodies for desirable uses and the narrative and numerical criteria deemed necessary to protect those uses.

Stormwater - Rainfall runoff, snow-melt runoff, surface runoff, and drainage.

Subwatershed – Any of several drainage areas that flow to a specific location and collectively form a watershed.

Sulfate (SO4-2) - An ion derived from rocks and soils containing gypsum, iron sulfides, and other sulfur compounds. Sulfates are widely distributed in nature.

SWQMIS – Surface Water Quality Monitoring Information System. A database that serves as a repository for surface water quality monitoring data for the state of Texas.

Texas Surface Water Quality Standards (TSWQS) – Standards that establish explicit goals for the water quality of streams, rivers, lakes, and bays throughout the state. The Standards are developed to maintain the quality of surface waters in Texas so that it supports public health and enjoyment and protects aquatic life, consistent with the sustainable economic development of the state. Water quality standards identify appropriate sues for the state’s surface waters, including aquatic life, recreation, and sources of public water supply. The TSWQS are codified in Title 30, Chapter 307 of the Texas Administrative Code.

Tidal - Descriptive of coastal waters subject to the ebb and flow of tides. For purposes of standards applicability, tidal waters are saltwater. Classified tidal waters include all bays and estuaries with a segment number that begins with 24xx, all streams with the word tidal in the segment name, and the Gulf of Mexico.

Total Dissolved Solids - The amount of material (inorganic salts and small amounts of organic material) dissolved in water and commonly expressed as a concentration in terms of milligrams per liter.

Total Maximum Daily Load (TMDL) - The total amount of a substance that a water body can assimilate and still meet the Texas Surface Water Quality Standards.

Total Suspended Solids - The amount of organic and inorganic suspended particles in water.

Tributary - A stream or river that flows into a larger one.

Use Attainability Analysis (UAA) – A structured scientific assessment of the factors affecting a water body’s attainment of specified uses.

Water body – Refers to any mass of water (lake, bay, river, creek, bayou, etc.).

Water Quality – The chemical, physical, and biological characteristics of water.

Watershed - The area of land from which precipitation drains to a single point. Watersheds are sometimes referred to as drainage basins or drainage areas.