Denton County, TX Environmental Rules: Stormwater Management (2026)

Denton County manages stormwater runoff under its TCEQ-issued MS4 permit, which requires the county to implement best management practices to reduce pollutants in stormwater discharge. All construction projects that disturb one acre or more of land must obtain coverage under the TPDES Construction General Permit (TXR150000) and prepare a Stormwater Pollution Prevention Plan (SW3P). The SW3P must include erosion and sediment control measures, construction phasing plans, and post-construction stormwater management features. Cities within Denton County including Denton, Lewisville, and Flower Mound have their own MS4 permits and stormwater ordinances that may impose additional requirements. The City of Denton requires stormwater detention or retention facilities for developments that increase impervious cover beyond pre-development conditions. Low-impact development techniques such as rain gardens, permeable pavement, and bioswales are encouraged and may reduce detention requirements in some jurisdictions. Illicit discharge to storm drains is prohibited under all MS4 permits. Residents and contractors must not allow construction sediment, chemicals, paints, oils, or other pollutants to enter the storm sewer system. Denton County provides a stormwater hotline for reporting illegal dumping and illicit discharges.