Last Updated 07/28/2026
Stormwater Code: Excerpts from Denton, Texas, Code of Ordinances and Land Development Ordinance
Stormwater Quality Management Requirements
2.0 - Stormwater Quality Management Requirements
The North Central Texas Council of Governments (NCTCOG) has published the Integrated Stormwater Management Design Manual (iSWM) which provides an integrated planning and design approach for addressing water quality protection for urban runoff. The iSWM methods that address urban Water Quality are required for the area of the Rayzor Ranch Development (site) that drains into the North Lakes Park Pond. A Water Quality Protection Plan that provides stormwater quality controls consistent with the iSWM is required for the Rayzor Ranch Development in order to minimize adverse impacts to the Park property and to preserve and protect the park pond resource for the citizens of Denton.
The total pollutant removal efficiencies for each stormwater quality control system used on the site (at the outlet) shall be as follows (derived from iSWM):
Total Suspended Solids = 80
% Total Phosphorus = 60%
Total Nitrogen = 50% Fecal
Coliform = no reduction
Metals = 80%
In addition to the iSWM removal efficiencies, Trash Removal Efficiency (all floatable objects) = 95% by volume.
2.3.1 - Recommended Stormwater Quality Control Practices
Control Practices are described in Section 1.4.2 of the iSWM. The following practices may be considered for this development. The identification of potential siting locations, screening, and selection of appropriate structural stormwater controls is the responsibility of the engineer.
Methods identified for consideration will only be considered which are expected to have a reasonable success rate, considering the site-specific soil conditions and topography. Onsite soils on the majority of the site were identified as Types C and D (high clay content) which provide limited opportunities for overland flow filtration zones for rooftop or pavement infiltration.
Table 5.1.3-1 Structural Control Screening Matrix in the iSWM Design Manual shall be used as a guide to determine the removal efficiencies for the selected control practices to be utilized. Either individual, on-site structural stormwater controls for each lot in the development, or a few strategically located regional stormwater controls in each sub-watershed may be used for controlling stormwater quality. The developer shall finance the design, construction, and maintenance of the controls.
- Bioretention Areas
- Extended Dry Detention Basins
- Multi-Purpose Detention Areas:
- Filtration
- Filter Strip
- Organic Filter
- Planter Boxes
- Surface Sand Filter/Permanent Sand Filter
- Underground Sand Filter:
- Gravity (Oil-Grit) Separator:
- Ponds: Stormwater ponds are constructed stormwater retention basins that have a permanent pool (or micropool) of water. Runoff from each rain event is detained and treated in the pool.
- Micropool Extended Detention
- Pond Multiple Pond Systems
- Wet Extended Detention Pond
- Wet Pond
- Proprietary Structural Controls
- Proprietary controls are manufactured structural control systems available from commercial vendors designed to treat stormwater runoff and/or provide water quantity control.
- Water Reuse Rain Harvesting (Tanks/Barrels)
- Rain harvesting is a container or system designed to capture and store rainwater discharged from a roof.
- Stormwater Wetlands
- Stormwater wetlands consist of a combination of shallow marsh areas, open water, and semi-wet areas above the permanent water surface.
- Extended Detention Shallow Wetland
- Pocket Wetland
- Pond/Wetland Systems
- Shallow Wetland
- Submerged Gravel Wetlands:
- Infiltration Trenches and Soakage Trenches may be considered if the soil percolation rates determined from onsite testing shows these practices can be successful.
2.4 - Inspections and Maintenance
The Water Quality Protection Plan required in Section 3.0 shall include a description of maintenance tasks, frequency of maintenance, responsible parties for maintenance, funding, access, and safety issues.
The use of stormwater ponds, wetlands, and extended detention basins shall require the submission of an operation and maintenance plan that addresses the potential for mosquito breeding in the treatment zone, and provides a contingency plan for controlling mosquito breeding using larvicides such as BTI or equivalent. A water balance calculation is required if a permanent wet pond utilizing fish for control is proposed by the developer.
Excerpt from Denton Watershed Protection
Post-construction stormwater management in areas undergoing new development or redevelopment is necessary because runoff from these areas has been shown to significantly affect receiving water bodies. Many studies indicate that prior planning and design for the minimization of pollutants in post-construction stormwater discharges is the most cost-effective approach to stormwater quality management.
There are generally two forms of substantial impacts of post-construction runoff. The first is caused by an increase in the type and quantity of pollutants in stormwater runoff. As runoff flows over areas altered by development, it picks up harmful sediment and chemicals such as oil and grease, pesticides, heavy metals and nutrients (e.g., nitrogen and phosphorus). These pollutants often become suspended in runoff and are carried to receiving waters, such as lakes, ponds and streams. Once deposited, these pollutants can enter the food chain through small aquatic life, eventually entering the tissues of fish and humans. The second kind of post-construction runoff impact occurs by increasing the quantity of water delivered to the water body during storms. Increased impervious surfaces (e.g., parking lots, driveways and rooftops) interrupt the natural cycle of gradual percolation of water and soil and into groundwater systems. Instead, water is collected from surfaces such as asphalt and concrete and routed to drainage systems where large volumes of runoff quickly flow to the nearest receiving water. The effects of this process include streambank scouring and downstream flooding, which often lead to a loss of aquatic life and damage to property.
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The information on this page is provided for general informational purposes only and is not legal advice. Regulations change frequently — AQUALIS makes no warranty as to the accuracy or completeness of this content, and any reliance on it is at your own risk. Consult a qualified professional or your local regulatory authority to confirm requirements applicable to your specific property.
