North Central Texas Water Quality Management Plan

The North Central Texas Council of Governments (NCTCOG) is the designated regional water quality planning agency for the North Central Texas area and is responsible for developing the regional Water Quality Management Plan (WQMP) and updating it annually. The WQMP helps determine regional priorities for improving water quality by identifying areas of potential concern. To that end, the WQMP provides data on water quality, water supply, and wastewater sources and discharges. The WQMP also includes information and website links to groups and partners, including NCTCOG’s programs, that are currently working to address water resources issues in the region.

The WQMP shows that elevated bacteria levels are a water quality concern in our region. Elevated bacteria levels are not only harmful to public health, but also to aquatic life by reducing oxygen levels in waterways. The sources of elevated bacteria include stormwater runoff of trash or chemicals on our landscapes (such as litter, pet waste, or excess fertilizers), permitted storm sewer sources, or improperly maintained or improperly functioning On-Site Sewage Facilities (OSSFs) (i.e., septic tanks). NCTCOG's Environment & Development Department is working to address these issues through its many programs and projects. Some examples of these efforts include engaging regional stakeholders on best stormwater management practices and monitoring, asking residents to “Doo the Right Thing” and pledge to trash pet waste, developing water quality educational materials, and working to gather data about OSSFs in the region.

Water resources planning and coordination is particularly important given that the NCTCOG population has been growing and is expected to continue growing through 2045. This growth impacts both water quality and supply. Since the first WQMP was developed in 1975, the NCTCOG 16-county region has grown by 5.7 million residents to its current 2024 population estimate of approximately 8.4 million. By 2045, the region is projected to increase to a population of about 11.4 million. (Source: 2024 NCTCOG Population Estimates Publication. NCTCOG, June 2024.)

The WQMP contains data from NCTCOG, the GIS Data Hub from the Texas Commission on Environmental Quality (TCEQ), and local sources. The WQMP is divided into 13 other sections, linked at the green bar above. Starting in 2020, the WQMP transitioned to this online interactive mapping journal to make the information easier to digest and more user-friendly. Please feel free to click on the maps in this report and read the pop-up windows that will appear or zoom in for more information on your local area.

The population for the 16-county NCTCOG region is estimated yearly by NCTCOG's Research and Information Services (RIS) Department. For 2024, the total population of the NCTCOG region is estimated to be 8,481,512. In 2023, the region's population increased by 196,622, which is higher than the amount added in 2022 by about 40,000 people. Dallas added more people (30,201) than any other city in 2023. The top ten most populous cities in the region are listed in the table below.

The newly updated population data show that the 16-county NCTCOG region continues to experience significant population growth.   Figure 1  shows the high levels of population growth in the Dallas-Fort Worth region from 2020 to 2024.  Forecasts project this trend will continue through 2045. The continual growth in the region is an important factor to consider for agencies tasked with maintaining or improving water quality, providing adequate capacity for wastewater treatment, and ensuring sufficient drinking water supplies.​

NCTCOG uses several methods of growth analysis to establish existing and projected growth trends in the North Central Texas region. Through this effort, as mentioned above, NCTCOG produces annual population estimates, and in 2017, population projections were estimated for 2045 for the 12-county Metropolitan Planning Area (MPA). The 2045 projection and the most recent population estimates can be found in  Figure 2 . The projected population data is useful for infrastructure planning and resource allocation in the MPA. The Texas Water Development Board (TWDB) also produces population projections, which NCTCOG references in its population measurements.

Analyses of where existing growth is occurring within the region are important to understand growth patterns and assist with future planning needs. To assist with this effort, NCTCOG develops an annual list of the population estimates for cities/towns in the NCTCOG region. The most recently updated list with estimates from 2020 to 2024 can be viewed or downloaded in  Figure 3 . Additionally, the map to the left shows the top ten cities/towns with the highest percent growth (in red) and largest absolute growth (in blue). Percent growth in population is defined as the relative change in population size from 2023 to 2024 and tends to be higher in smaller cities/towns. Absolute growth is defined as the actual number of people the population increased by from 2023 to 2024 and tends to be higher in larger cities/towns. The absolute growth and percentage growth values for the top ten cities or towns can also be viewed in a tabular format in  Figure 4. 

The map to the left also shows that the four core counties in the NCTCOG region, Collin, Dallas, Denton, and Tarrant counties, contain most of the region's population and are also experiencing the most significant portion of the absolute population growth compared to the rest of the NCTCOG region. These counties are responsible for an estimated 85% of the 2024 population in the NCTCOG region and will continue to increase in population through 2045, according to the NCTCOG 2045 population projections. Actual values can be found in   Figure 5a .​ Similar to Figure 4,  Figures 5b and 5c  display the top five counties experiencing the largest amount of growth by percentage and in absolute numbers. The counties with the highest growth percentage- Rockwall, Ellis, Collin, Johnson, and Somervell- highlight the trend of continued growth beyond "the core" of the region.

NCTCOG supports the development and implementation of the   TMDL Implementation Plan (I-Plan)   to address bacteria levels in the Greater Trinity River region. TMDL boundaries in the NCTCOG region are shown on the corresponding map. A TMDL establishes the amount of pollutant that a stream segment can receive and still maintain the water quality standards for its designated use. 

The I-Plan was approved by TCEQ Commissioners in 2013 and initially included 17 TMDLs. It was updated in 2017 to include an additional four TMDLs, and again in mid-2019 to include an additional TMDL for Sycamore Creek. In late 2019, it was updated to include segment 0841Q in the Mountain Creek Lake Tributaries portion of the TMDL I-Plan area. The I-Plan describes strategies that can be taken to reduce the levels of bacteria loading in portions of the Trinity River and its tributaries that are listed as impaired for bacteria in the Integrated Report and Texas 303(d) List. The I-Plan has outlined implementation strategies to reduce bacteria loading in the following waterways:

• Upper Trinity River (Segment 0805)

• Cottonwood Branch and Grapevine Creek (Segments 0822A and 0822B)

• Lower West Fork Trinity River (Segments 0841, 0841B, 0841C, 0841E, 0841G, 0841H, 0841J, 0841L, 0841M, 0841R, 0841T, and 0841U) 

• Mountain Creek Lake Tributaries (Segments 0841F, 0841K, 0841N, 0841Q, and 0841V)

• Sycamore Creek (Segment 0806E)

The TMDL I-Plan efforts have been outlined in the  2023 TMDL Annual Program Summary , a two-page, user-friendly document.

TCEQ utilizes several tools to determine appropriate water quality standards for stream segments in the state. The Use Attainability Analysis (UAA) is a study to evaluate, or reevaluate in some cases, the designated use of a water body. The analysis will be conducted if the water body's water quality standard calls into question the appropriate use to support local needs. This assessment is based on the physical and flow characteristics of the stream, supporting information from individuals and organizations with firsthand knowledge, and historical and existing patterns of use.  ¹ 

The most common UAA is the Recreational Use-Attainability Analysis (RUAA). The RUAA determines which of four recreational use categories is appropriate for a particular water body. They are:

• Primary Contact Recreation: Activities that are presumed to involve significant risk of ingestion of water.
• Secondary Contact Recreation 1: Activities that commonly occur, but have limited body contact, incidental to shoreline activity.
• Secondary Contact Recreation 2: Activities with limited body contact, incidental to shoreline activity.
• Non-contact Recreation: Activities that do not involve a significant risk of water ingestion, such as those with limited body contact, incidental to shoreline activity. 

RUAA studies within the NCTCOG region, as of April 3, 2024, can be viewed by clicking on the map or by viewing  Figure 8  . Performing a RUAA has the potential to change the designated water quality standard of a waterway, causing the waterway to achieve attainment for certain pollutants and no longer be considered impaired. Stream segments with pending outcomes are still awaiting EPA approval of TCEQ recommendations.

  ¹   TCEQ's RUAA Website:   https://www.tceq.texas.gov/waterquality/standards/ruaas 

In the 2021 Update to the North Central Texas WQMP, NCTCOG initiated work to create a centralized, spatial database of OSSFs in the 16-county NCTCOG region, and this effort continues in the 2024 Update to the WQMP. An OSSF, also known as a septic system and usually consisting of a septic tank and a drainage field, treats and disposes wastewater at the site where the wastewater is created. These sites are typically single-family residences and businesses that are not connected to public wastewater infrastructure and can be found in rural, suburban, or urban areas. In Texas, there are over two million OSSFs and these systems are installed in approximately 20% of the state's residential new builds.  ^1,2  

NCTCOG obtained the locations of OSSFs shown on the map by contacting authorized OSSF permitting agents in the region. A permit is required to construct, alter, repair, extend, or operate an OSSF in Texas after September 1, 1989. TCEQ regulates OSSFs in Texas, but delegates this authority to authorized agents at the local or county level.  ³  Over 75 authorized agents in the NCTCOG region maintain the permit data in various formats: digital spreadsheets, digital shapefiles, paper files, or a combination thereof, so contacting these agencies and collecting the data is a substantial effort.  ⁴   The map below shows locations gathered and geocoded as of May 18, 2024, for Denton County, Erath County, Hood County, Hunt County, Johnson County, Kaufman County, Navarro County, and Parker County, Somervell County, Tarrant County along with the communities of Argyle, Arlington, Bartonville, Bridgeport, Burleson, Cedar Hill, Crossroads, Flower Mound, Ennis, Grand Prairie,  Hickory Creek, Krugerville, Millsap, Northlake, Oak Point, and Red Oak, as well as various unincorporated communities. Data gathering efforts will continue over the next year and an update will be provided in the 2025 Update to the WQMP. The locations of unpermitted OSSFs built prior to September 1, 1989, are more difficult to determine and will likely be included in the database to be showcased in a future WQMP Update.

Proper design, installation, and periodic routine maintenance are key to keeping OSSFs functioning properly, and therefore, maintaining their ability to effectively treat wastewater. However, OSSFs can leak untreated wastewater into groundwater and surface waters when not properly designed or maintained. These leaks endanger human health by releasing pathogens into the environment, and threaten the health of our waterways through increased nutrient loading, decreased dissolved oxygen levels, fish kills, and problems with other aquatic life.  ⁵   In Texas, estimates show that an average of about 13% of OSSFs are failing.  ⁶  

A lack of knowledge about the proper maintenance of OSSFs has been identified as one of the contributing factors to failing OSSFs.  ⁶   In order to assist communities with educating homeowners, NCTCOG provides outreach resources, including an OSSF Educational Social Media Toolkit, an OSSF mailer, an educational video for homeowners, and workshop materials. These items can be found on   NCTCOG’s TMDL website   under the green banner called “Septic System (OSSF) Resources."

  ¹  Texas Water Quality and Septic Systems. Kerry Halladay. Texas Water Resources Institute. August 2020.   https://twri.tamu.edu/news/2020/august/texas-water-quality-and-septic-systems  

  ²   TCEQ website, "Basics for Septic Systems."

  https://www.tceq.texas.gov/assistance/water/fyiossfs.html  

  ³   TCEQ website, "Getting a Permit for an On-Site Sewage Facility - Such as a Septic System."

  https://www.tceq.texas.gov/permitting/ossf/ossfpermits.html  

  ⁴   TCEQ website for locating OSSF permitting authorities.

  https://www6.tceq.texas.gov/oars/index.cfm?fuseaction=search.county  

  ⁵   EPA website, "Why Maintain Your Septic System."

  https://www.epa.gov/septic/why-maintain-your-septic-system  

  ⁶   Reed, Stowe, and Yanke, l.LC. Study to Determine the Magnitude of, and Reasons for, Chronically Malfunctioning On-Site Sewage Facility Systems in Texas. Austin, Texas: On-Site Wastewater Treatment Research Council, 2001.

Disclaimer: The points on the map are intended for general illustrative, reference, and planning purposes only. Mapping may not reflect on the ground conditions. NCTCOG makes no further claims as to the accuracy or reliability of the data, and neither assumes, nor will accept liability for their use.

The NCTCOG region utilizes analyses on available water supply, water shortage, and water demand developed by the  Region C Water Planning Group   (WPG) who are tasked with developing a regional water plan to recommend management strategies for water in North Texas. The  2021 Region C Water Plan  projects that over 90% of the water demand in 2070 will be for municipal users and predicts Collin, Dallas, Denton, and Tarrant counties will have the largest water needs in the Region C area in 2070. ¹  These forecasted needs encourage regional stakeholders to continue collaborating on best management strategies for meeting future water supply demands. NCTCOG supports the Region C management strategies for achieving water supply goals as laid out in the 2021 Region C Water Plan. 

There are 16 regional water planning areas in Texas. Six of the counties in the NCTCOG region fall into different regional water planning jurisdictions (see the corresponding map). However, the recommendations for water management strategies serve to accomplish the same goals as Region C. The   Region G Water Plan  serves Palo Pinto, Erath, Hood, Somervell, and Johnson counties, and the  Region D Water Plan  serves Hunt County.

In the 2021 Region C Water Plan, the Region C WPG defines major water management strategies as those that would supply more than 30,000 acre-feet per year or more. (An acre-foot is defined as 325,851 liquid gallons.)  ²  Since the 2023 WQMP Update, one reservoir, Bois d'Arc Lake, has completed construction, and another, Lake Ralph Hall, continues its development. Both reservoirs will supply water to the northern portion of the NCTCOG region and can be found on the corresponding map just outside the NCTCOG region in Fannin County.

The North Texas Municipal Water District (NTMWD) began constructing Bois d’Arc Lake in Fannin County in May 2018. The construction of this reservoir is a recommended strategy from the Region C WPG.  ³   NTMWD began impounding water in April 2021 and the reservoir officially opened in the fall of 2022. In the spring of 2023, water delivery from Bois d-Arc Lake began from NTMWD’s new water treatment plant in Leonard, and in 2024, the lake opened for recreational use. The reservoir comprises about 26 square miles of surface area and provides a firm yield of 82 million gallons per day. Water from Bois d’Arc Lake will help supply projected water demands in the region until almost 2040.

In September 2013, Upper Trinity Regional Water District was granted a water rights permit from the State of Texas to develop Lake Ralph Hall on the North Sulphur River in Fannin County. In January 2020, the U.S. Army Corps of Engineers issued a section 404 Clean Water Act permit. This is the final federal permit required to construct the reservoir. Currently under construction, Lake Ralph Hall is projected to produce 39,220 acre-feet a year, or 54 million gallons per day, 19 million gallons a day of which will be from reuse. Water from Lake Ralph Hall will be delivered to Denton County and is expected by 2026.  ⁴  By the end of 2023, Lake Ralph Hall had begun construction on the pump station and pipeline system. Construction of this lake is a recommended water supply strategy from the Region C WPG. The locations for Bois d’Arc Lake and Lake Ralph Hall can be seen on the map to the right, along with a timeline of overall reservoir construction in the North Central Texas region. 

According to the 2021 Region C Water Plan, the reuse of treated wastewater effluent is becoming an increasingly important source of water in Region C. Reuse is projected to comprise 31% of the 2070 water supply for the Region C water planning area.  ⁵   The two types of reuse are:

Indirect Reuse - the placement of water, typically treated effluent, back into a water supply source, such as a lake, river, or aquifer, and then retrieved to be used again; and

Direct Reuse - treated wastewater is delivered from a wastewater treatment plant to a water user, with no intervening discharge to waters of the state.

Each category can be further defined by the end use, either potable (drinking purposes) or non-potable (non-drinking purposes). In North Central Texas, reuse typically occurs as direct non-potable reuse or indirect potable reuse. Direct non-potable reuse programs require notification to TCEQ, obtainment of a 210 Use of Reclaimed Water permit, and meeting state-designated regulations designed to protect public health. This type of reuse is most commonly used to supply water for landscape irrigation and industrial uses.

Indirect potable reuse affects water rights in Texas and requires entities to demonstrate that its reuse scheme will not negatively impact downstream water rights holders.  ⁶   Indirect potable reuse programs use reclaimed water to augment drinking water supplies by discharging it to a water body, such as groundwater or surface water, which is subsequently treated for potable consumption. NTMWD implemented an indirect potable reuse project in Lavon Lake in 1985, diverting water from a wastewater treatment plant and treating it for municipal use as drinking water.  ⁷  

During the 84th Texas Legislative Session, TWDB and TCEQ were directed to support the creation of a direct potable reuse model under House Concurrent Resolution (HCR) No. 74.  ⁸   HCR No. 74 identified the Dallas-Forth Worth Metroplex as the region to develop the model, as it is projected to house 32% of the state’s population by 2070. Between 2020 and 2070, the metroplex is also projected to see a 71% increase in demand for new water supplies.  ⁹   The model reuse project, in conjunction with renewable energy technologies, could provide opportunities for public education on water reuse and renewable energy.

The Legislative action predicts that the creation of a direct potable reuse project in Region C of the TWDB Water Planning Area has the potential to yield sufficient water supply to regional residents while alleviating the depletion of already scarce resources.

Additional research is being conducted to explore the feasibility of Aquifer Storage and Recovery (ASR) projects in Region C to keep up with regional water demand. ¹⁰  ASR involves the storage of surplus surface water, treated wastewater, or groundwater, which can then be extracted and distributed when the water demand is high or supply is low. These projects, should they prove cost-effective and suitable for achieving regional goals, could prove to be an additional water resource during times of drought or peak demand.

Water conservation is a crucial part of ensuring future water supply and improving water quality for North Central Texas. Based on questionnaire responses on existing water conservation strategies occurring in Region C and historical water use data, the Region C WPG determined that significant efforts have been made by water providers and water users to conserve water in the region. To this end, the WPG will continue to place a strong emphasis on water conservation and reuse as a means to reach water supply goals for future needs.

In the NCTCOG regional planning area, there are significant efforts underway to promote the effectiveness of water conservation. Conservation is an important component of water resources in the region. Regional stakeholders and municipalities conduct public education, develop water conservation plans, implement green infrastructure, utilize water reuse, and implement watershed protection strategies in order to obtain water conservation goals for future demands.

   ¹   2021 Region C Water Plan. p. 14-15.

  https://www.twdb.texas.gov/waterplanning/rwp/plans/2021/index.asp#region-c  

  ²   2021 Region C Water Plan. p. 5C-1. 

  https://www.twdb.texas.gov/waterplanning/rwp/plans/2021/index.asp#region-c  

  ³   Bois d'Arc Lake website. 

  https://boisdarclake.org/about/fast-facts/  

  ⁴   Lake Ralph Hall website. 

  https://lakeralphhall.com/  

  ⁵   2021 Region C Water Plan. p. ES.8, Figure ES.4.

  https://www.twdb.texas.gov/waterplanning/rwp/plans/2021/index.asp#region-c      

 ⁶   Requirements for Reclaimed Water, TCEQ February 28, 2020.

  https://www.tceq.texas.gov/assistance/water/reclaimed_water.html  

  ⁷   History of Water Reuse in Texas, TWDB February 2011. 

  http://www.twdb.texas.gov/innovativewater/reuse/projects/reuseadvance/doc/component_a_final.pdf  

  ⁸   HCR No. 74, 84th Texas Legislative Session, 2015. 

  https://www.legis.state.tx.us/tlodocs/84R/billtext/html/HC00074I.htm  

  ⁹   2017 Texas State Water Plan, p. 52 and 55, respectively, updated February 2020.

  https://www.twdb.texas.gov/waterplanning/swp/2017/index.asp 

 ¹⁰  2021 Region C Water Plan, p. 5C-31.  https://www.twdb.texas.gov/waterplanning/rwp/plans/2021/index.asp#region-c