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HomeNL-2020-09 Water Quality

How is the Quality of Our Surface Water Protected?
by Tom Douglas

Getting Started

For an introduction to the protections that are in place for the water quality of the streams, lakes, and bays where we paddle, I recommend reading the publication Preserving & Improving Water Quality. Some of these protections come from the federal government, others from the state. And, as we will see, these two jurisdictions often interact. Although I have avoided referencing sections of legal documents by their numerical designations, these are readily available by following the relevant hypertext links. 


Defining “Surface Water”

In legal terms, the places where we paddle are classified as “surface water”.  As such, they are owned by the State of Texas, which holds them in trust for its citizens. According to the Texas Administrative Code, “Surface Water” is defined as:

“Lakes, bays, ponds, impounding reservoirs, springs, rivers, streams, creeks, estuaries, wetlands, marshes, inlets, canals, the Gulf of Mexico inside the territorial limits of the state as defined in the Texas Water Code, §26.001, and all other bodies of surface water, natural or artificial, inland or coastal, fresh or salt, navigable or nonnavigable, and including the beds and banks of all water-courses and bodies of surface water, that are wholly or partially inside or bordering the state or subject to the jurisdiction of the state; except that waters in treatment systems that are authorized by state or federal law, regulation, or permit, and that are created for the purpose of waste treatment are not considered to be water in the state.”

State Standards for Water Quality

Texas Surface Water Quality Standards are rules developed to maintain the quality of surface water in Texas so that it supports public health and enjoyment and protects aquatic life, consistent with the sustainable economic development of the state. Each standard has two basic elements: a use such as contact recreation, and the criteria necessary to attain and maintain that use, such as the maximum permissible concentration of a particular contaminant. They are written by the Texas Commission on Environmental Quality, under the authority of the federal Clean Water Act and the Texas Water Code. To ensure compatibility with the federal Clean Water Act, they must also be approved by the U.S. Environmental Protection Agency.


Monitoring for “Indicator Bacteria”

Approximately 80 percent of our area’s streams fail to meet one or more of the state surface water quality standards, most often because of excessive levels of bacteria. Rather than testing for specific bacteria that cause disease in humans, surface water quality monitoring programs focus on the enumeration of indicator bacteria, whose presence may signal contamination of the water with fecal waste. Because contamination due to human waste is of particular public health concern, there has been a trend over time toward testing for bacteria that are often associated with humans. The most commonly used indicator bacteria at this time are Escherichia coli for freshwater and enterococci for saltwater.


Unless Shown Otherwise, the Water Quality of a Surface Water Must not be Hazardous for Paddlers

A particular water body must be designated for the very highest category of use, i.e. "primary contact recreation 1”,

“unless sufficient site-specific information demonstrates that elevated concentrations of indicator bacteria frequently occur due to sources of pollution that cannot be reasonably controlled by existing regulations, wildlife sources of bacteria are unavoidably high and there is limited aquatic recreational potential…”

Primary contact recreation 1” is defined as:

“Activities that are presumed to involve a significant risk of ingestion of water (e.g., wading by children, swimming, water skiing, diving, tubing, surfing, handfishing as defined by Texas Parks and Wildlife Code, §66.115, and the following whitewater activities: kayaking, canoeing, and rafting).”

If the usage of a waterway by paddlers were to be the only criterion considered, the situation would be less clear, depending upon the frequency at which the risk of ingestion of water is presumed to occur. 


Point Sources and Nonpoint Sources of Pollution

Sources of pollution fall into two broad categories: point sources and nonpoint sources. A point source, sometimes informally referred to as an “end of pipe” source, is defined as

“Any discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft, from which pollutants or wastes are or may be discharged into or adjacent to any water in the state.”

Common examples of point sources are wastewater treatment facilities, concentrated animal feeding operations, and industrial facilities. All other sources fall into the category of nonpoint sources. A common example of a nonpoint source is the water that runs off from the surface of undeveloped land following a rain.


Point Sources of Pollution Require Permits

The authority of a point source to discharge pollutants into a surface water body is governed by a permit. With the passage of the Clean Water Act in 1972, the National Pollutant Discharge Elimination System (NPDES) was created to administer this permitting process. In 1998, the state of Texas assumed the authority to administer the NPDES program through the Texas Pollutant Discharge Elimination System (TPDES). In general, the provisions of these permits are based on the Texas Surface Water Quality Standards, which are written by the Texas Commission on Environmental Quality (TCEQ) and approved by the U.S. Environmental Protection Agency (EPA). For example, the permit for a wastewater treatment facility would typically specify the maximum volume of effluent that can be discharged per day, plus the maximum concentration of viable indicator bacteria that can be present in that effluent.


Bacterial Concentration and Bacterial Load

A common procedure that is used in water quality monitoring is to collect a water sample, take it back to the lab, and use a bacterial culture method such as growth in a Petri dish to determine the number of viable bacteria present per unit volume of the sample. To satisfy the criterion for the “Primary contact recreation 1” use of a waterway, this concentration may not exceed 126 viable bacteria per 100 milliliters when E. coli is used as the indicator, or 35 viable bacteria per 100 milliliters when enterococci are used. (As illustrated in the following diagram, 100 milliliters is equal to approximately 3.4 US fluid ounces.) The concentration that is reported is actually determined by averaging the numbers from several different samples. To reduce the amount of variation due to differences among the individual samples, a geometric mean is used instead of the more familiar arithmetic average. The term “bacterial density” is sometimes used interchangeably with “bacterial concentration”.



A stream’s total bacterial load is calculated by multiplying the bacterial concentration, determined as described above, by the total volume of water that flows past a point on the stream’s bank per unit of time (bacteria/volume X volume/time = bacteria/time). The concept of bacterial load might be imagined by thinking of a person sitting on the stream’s bank with a clipboard, counting individual viable bacteria as they passed by. After a whole day of observation, they would know the stream’s bacterial load, expressed as the number of viable bacteria that went by in a day’s time. As noted below, the concept of bacterial load is critical to the calculations that are required for a Total Maximum Daily Load project


The Importance of Monitoring

Most people are surprised to discover the degree to which treated wastewater may contribute to stream flow in a heavily urbanized area. Especially during times of low rainfall, essentially 100% of the flow in some of our local creeks and bayous may be attributable to this source. Consistent sampling and testing of water bodies can detect when problems are present, and the pattern of results over time may also provide a valuable clue to the source(s) of bacteria. High levels of bacteria that occur during periods of drought are most likely due to point sources, while high levels of bacteria observed following rains probably come from nonpoint sources.     


The Texas Integrated Report of Surface Water Quality

Once every two years, each state is required to prepare an updated list of its water bodies that are not meeting state water quality standards. For each paired set of a water body with its relevant contaminant, a plan must be developed to address the issue that is causing the impairment. This may take the form of a Watershed Protection Plan, which is voluntary, or a Total Maximum Daily Load (TMDL) project, which has regulatory authority. If the water body does not meet applicable water quality standards for one or more designated uses by one or more pollutants, a TMDL project may be required. In other cases, where a water quality standard “is not supported for one or more designated uses but … other control requirements are reasonably expected to  result in the attainment of all standards”,  a Watershed Protection Plan may suffice. Texas has been a leader in this alternative approach. Because a Watershed Protection Plan is not as tightly focused on the TMDL calculation for a single contaminant (see below), it can offer much greater latitude for interested community stakeholders to address a variety of water quality-related issues that are important to them. For either a Watershed Protection Plan or a TMDL project, the geographical boundaries for the plan will correspond to the boundaries of the physical watershed, rather than to those of a political subdivision such as a county.


Total Maximum Daily Load (TMDL)

A TMDL is the calculation of the maximum amount of a pollutant that can be allowed to enter a water body so that it will meet and continue to meet the water quality standard for a particular pollutant such as bacteria. A TMDL project first determines a pollutant reduction target, then it allocates the load reductions that will be necessary to achieve this goal. Expressed mathematically, the TMDL equation is: TMDL = ΣWLA + ΣLA + MOS, where ΣWLA is the sum of wasteload allocations (point sources), ΣLA is the sum of load allocations (nonpoint sources and background), and MOS represents a margin of safety. A TMDL project has the regulatory authority to require permitted sources (WLAs) to meet the goal. Educational programs, such as those that encourage pet owners to clean up pet waste, may be instituted to reduce the LAs. 


How Plans are Funded and Administered

Funding for developing a plan to deal with nonpoint sources is available through federal grants made under the Clean Water Act. At the state level, these grants are administered through the Texas State Soil and Water Conservation Board (for rural areas) or the Texas Commission on Environmental Quality (for urban areas). Application for these grants is open to nonprofit organizations, state agencies, and political subdivisions of the State of Texas, such as cities, counties, school districts, state universities, and special districts. Entities that have played this role in our area include the Houston Advanced Research Center, Houston-Galveston Area Council, and Texas AgriLife Extension’s Texas Coastal Watershed Program


The State of Texas Water Quality Management Plan for Wastewater Treatment

As required under the Texas Water Code and the federal Clean Water Act, the State of Texas Water Quality Management Plan (WQMP) is a wastewater treatment plan that is used to direct planning for implementation measures that control and/or prevent water quality problems. Several elements may be included in the WQMP, such as effluent limitations of wastewater facilities, total maximum daily loads (TMDLs), nonpoint source management controls, identification of designated management agencies, and ground water and source water protection planning. This plan is updated on a quarterly basis, to include all applications for new and amended water quality permits. Texas is divided into 24 regions, each served by a voluntary Council of Governments (COG) that coordinates programs and services to address needs that cross jurisdictional boundaries. The COGs that encompass six of the state’s most populous regions are designated as Water Quality Planning Agencies, and receive grant funding from TCEQ, via the EPA.  The COGs that include the Dallas/Fort Worth region (North Central Texas Council of Governments) and the Houston/Galveston region (Houston-Galveston Area Council) are required to submit formal WQMP updates annually. Following certification by the TCEQ and approval by EPA, each of these updates will become part of the state plan. 

Helpful Maps Related to Surface Water Quality

If you would like to explore our regional watersheds in more detail, there are several sources of maps that you may find particularly helpful:

SWQV 400 px

Keeping an Eye on Surface Water

The author, Tom Douglas