Success of Wastewater Treatment Plant Regionalization. In the 1930s, secondary treatment of wastewater began, but water quality continued to remain poor. Beginning in the 1970s, however, advances in wastewater treatment resulted in dramatic improvements. In 1971, implementation of the Upper Trinity River Basin Comprehensive Sewer Plan resulted in the “regionalization” of WWTPs. Regionalization resulted in the elimination of many small, independently operated municipal and industrial WWTPs and the adoption of larger, regional systems that were better able to treat effluent to much higher standards. The following year in 1972, Congress passed the Clean Water Act (CWA), which established the basic structure for wastewater discharge permitting and standards. Water quality improvements in the Trinity River Basin are tied to technological advances that were possible because of the operation of the Covered Parties’ regionalized WWTPs. Long-term water quality data has been collected at the TCEQ Surface Water Quality Monitoring (SWQM) site 10925 in Xxxxx and Xxxxxxx Counties5 for decades. A review of historical total ammonia nitrogen from this site, which can be harmful to aquatic organisms at some level, has fallen dramatically since 1985. Between 1972 and 1985, total ammonia nitrogen averaged 3.4 milligrams per liter (mg/L); from 1985 to present, average ammonia nitrogen levels have decreased 95% and now hold steady averaging 0.16 mg/L (Figure 3). Simply, biochemical oxygen demand (BOD) is a measure of the amount of organic and inorganic material in the water. The Covered Parties’ Regional WWTPs use an activated sludge treatment 5 TCEQ Surface Water Quality Monitoring Station number 10925 is located at the Trinity River and State Highway 34 just below the confluence of the East Fork Trinity River. This has been used for decades to represent the water quality for the entire DFW area since it captures all of the urban runoff and effluent from all of the major WWTPs in the DFW area, including the Covered Parties’ WWTPs. process for the major plants which is very efficient in the removal of BOD. A review of historical BOD data at SWQM site 10925 shows a dramatic decrease in average BOD since 1985. Between 1968 and 1985, BOD averaged 13.4 mg/L; since then, BOD has decreased by 81% to 2.5 mg/L (Figure 4). Overwhelmingly, these water quality improvements are due to the Covered Parties’ efforts since the early 1970s to convert onsite septic systems and small, dysfunctional package plants to large, sophisticated Regional WW...
Success of Wastewater Treatment Plant Regionalization. In the 1930s, secondary treatment of wastewater began, but water quality continued to remain poor. Beginning in the 1970s, however, advances in wastewater treatment resulted in dramatic improvements. In 1971, implementation of the Upper Trinity River Basin Comprehensive Sewer Plan resulted in the “regionalization” of WWTPs. Regionalization resulted in the elimination of many small, independently operated municipal and industrial WWTPs and the adoption of larger, regional systems that were better able to treat effluent to much higher standards. The following year in 1972, Congress passed the Clean Water Act (CWA) which established the basic structure for wastewater discharge permitting and standards. The Covered Parties’ regionalization of wastewater service in the DFW area is the 'most significant driver for water quality improvements in the Trinity River Basin. Together, the Covered Parties spend over $397 million dollars5 annually to operate 18 major6 WWTPs, which as of December of 2022, are permitted to convert up to 978.4 million gallons per day (MGD) of raw sewage into high-quality effluent (see Section 6.2.1, Figure 15, and Table 6-1 for more detail). This discharged effluent provides aquatic habitat for organisms including the Covered Species and their host fish for the entirety of the 325 miles of the Trinity River from the DFW area to Lake Xxxxxxxxxx. During periods of drought, this water provides approximately 500 cubic 5 This number represents only those funds (fiscal year 2023 budgets) dedicated to operation of the treatment plants and does not include the significant other costs involved with the inspection, maintenance, and repair of the collection systems (pipelines).
