Denton County (Unincorporated)
Denton County Development Services
CountyMS4 Phase IIVerified 2026-03
Local Permit / Authorization
- Permit Required
- Yes
- Permit Name
- Floodplain Development Permit / Drainage Review
- Submit To
- Denton County Development Services
- Lead Time
- Plan review typically 2–4 weeks
- Application Method
- Submit via Denton County Development Services at 401 W. Hickory St., Denton, TX 76201 or online portal
- Fee
- Contact agency for current fee schedule
Water Quality Standards
- Impervious Cover Limit
- No countywide impervious cover cap; drainage systems must accommodate design storm flows per Denton County Drainage Design Criteria
- On-Site Treatment Required
- No
- Detention Required
- Yes
- Detention Standard
- Detention required to limit post-development peak flows to pre-development levels for 2-, 10-, and 100-year storms per Denton County Drainage Design Criteria; applies only in unincorporated areas
- Turbidity Standard
- No numeric NTU limit; discharges must comply with TCEQ TXR150000 and not degrade Elm Fork Trinity River, Ray Roberts Lake, or Lewisville Lake
Local SWPPP / Drainage Plan
- Local Plan Required
- Yes
- Plan Name
- SWPPP per TCEQ TXR150000; drainage report required for county permits
- PE Stamp Required
- Yes
Drainage study prepared by a Texas PE required for development permits in unincorporated Denton County. The county is experiencing explosive growth with many large master-planned communities developing in ETJ areas. Projects near city ETJ boundaries should verify which jurisdiction's standards apply — cities often have review authority in their ETJs.
Local Inspection Requirements
- Requirements
- Denton County Development Services inspects development permits in unincorporated areas. Rapid growth across the county means frequent BMP inspection is critical.
- Inspector Qualification
- No county-specific certification required beyond TCEQ SWPPP requirements
Special Overlay Zones
Lake Ray Roberts Watershed
Trigger: Development in the contributing watershed to Lake Ray Roberts (USACE/NTMWD water supply reservoir in northern Denton County)
Restriction: Enhanced water quality BMPs required; coordinate with North Texas Municipal Water District and USACE Fort Worth District for projects near the lake boundary
Lewisville Lake Watershed
Trigger: Development draining to Lewisville Lake (USACE reservoir on the Elm Fork Trinity)
Restriction: Water quality BMPs required; USACE manages the lake and shoreline; avoid direct discharge to lake tributaries without adequate sediment control
Elm Fork Trinity River Floodplain
Trigger: Development within FEMA-mapped 100-year floodplain along the Elm Fork Trinity and its tributaries
Restriction: Floodplain development permit required from Denton County Floodplain Administrator; no net fill without compensatory storage
Extraterritorial Jurisdiction (ETJ) of Cities
Trigger: Development in the ETJ of Denton, Lewisville, Flower Mound, Frisco, Little Elm, and other cities within Denton County
Restriction: City ETJ review authority may require conformance with city design standards even for county-permitted projects; verify ETJ boundaries with applicable city before submittal
Design Manual
- Manual Name
- Denton County Drainage Design Criteria
Official Resources
Jurisdiction Notes
Denton County is one of the fastest-growing counties in the United States, with booming growth in cities like Frisco, McKinney (northern part), Little Elm, Prosper, Celina, and unincorporated areas. The county seat is the City of Denton. This entry covers unincorporated Denton County — most major cities have their own permit requirements. The county contains two major USACE reservoirs (Ray Roberts and Lewisville) that serve as North Texas water supplies. Lake Ray Roberts, completed in 1987, has strict water quality protection requirements in its watershed.
Remember: These local requirements are in addition to the TCEQ state construction permit. Both must be satisfied before breaking ground.
Disclaimer: This information is provided for general reference only. Always verify requirements directly with Denton County Development Services and the agency website before beginning construction.