Watershed Protection is a division within the Environmental Services and Sustainability Department. The Watershed Protection Program was initiated in January 2001 as a part of a plan to reduce the overall pollutants within the surface waters of Denton and to ensure compliance with the National Pollution Discharge Elimination System (NPDES) Storm Water Phase II rule. As a NPDES phase II City, Denton operates and maintains a ‘municipal separate storm sewer system’ or MS4 for residents and businesses within the City of Denton.
Watershed Protection services include (but not limited to):
- Detecting and eliminating illicit discharge
- Construction stormwater inspections
- Review of Stormwater Pollution Prevention Plans (SWPPPs) and erosion control plans
- Ensuring regulatory compliance with NPDES
- Environmentally Sensitive Area Assessments
- Coordination of City of Denton Volunteer Environmental Monitors
- Industrial stormwater inspections
- Municipal good housekeeping
This program incorporates the infrastructure established by an Environmental Protection Agency EMPACT grant awarded to the City of Denton and the University of North Texas in 1998. During the first year of the Watershed Protection Program, monitoring results from the EMPACT system and additional watershed monitoring were used to establish preliminary baseline conditions for the physical, chemical, and biological components of the city's surface water resources. Results from this monitoring program are used to support the requirements of the Phase II storm water program, assess water quality for the purposes of source water protection, and establish baseline conditions that can be used to evaluate any future changes in water quality.
Cooper Creek, Hickory Creek, Pecan Creek and Clear Creek are the four main watersheds that convey water through Denton. Using topographical information, approximately 85 sub-basins have been delineated within the city. Sampling stations were established within these sub-basins at locations that would likely represent the water quality of the sub-basins. Monitoring of these sub-basins during base-flow conditions was initiated in January 2001 and has continued on a monthly basis ever since. Parameters analyzed in the tributary samples include conventional flow, temperature, dissolved oxygen, pH, conductivity, turbidity, salinity, litter index, visual evaluation and odor. Bimonthly, ten sampling stations are randomly selected for more intense analysis which included E. coli
bacteria, metals, phosphorus, nitrogen, ammonia, nitrate, chlorides, sulfates, alkalinity, hardness, total solids and total suspended solids.
Permanent monitoring stations were established near the ends of the three major watersheds (Hickory, Pecan and Cooper Creeks) prior to the confluence of the watersheds with Lewisville Lake. These include a station above and below the Pecan Creek Water Reclamation Plant's outfall. More extensive monitoring is conducted at these stations to provide a more comprehensive assessment of the combined effects of sub-basin water quality just prior to entering the city's main drinking water source, Lewisville Lake.
The data from the stream monitoring program are analyzed with the following objectives:
- Characterize the general water quality condition of the stream
- Identify illicit discharges
- Identify long-term water quality trends