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Williamson County(3 more)
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| Field | Local Williamson County Williamson County Road and Bridge Department / Engineering Division |
|---|---|
| Permit | |
| Permit / Authorization | Drainage Permit |
| Submit To | Williamson County Road and Bridge Department / Engineering Division |
| Lead Time | Typically 3–6 weeks for standard projects; larger submissions may require 6–10 weeks given high development volume |
| Application Method | Submit drainage permit application to Williamson County Road and Bridge Engineering. In person at the Georgetown office. Contact (512) 943-3330 for current submittal requirements. |
| Fee | Contact agency for current fee schedule |
| Water Quality | |
| Impervious Cover Limit | No county-wide impervious cover cap for most unincorporated areas. Edwards Aquifer Recharge Zone areas subject to TCEQ Chapter 213 rules with stricter impervious cover limitations. |
| On-Site Treatment Required | Yes |
| Detention Required | Yes — Post-development peak discharge must not exceed pre-development peak discharge for the 2-, 10-, and 100-year design storm events per Williamson County Drainage Criteria. Water quality controls required to capture and treat the first flush (1.5-inch rainfall depth) before discharge. |
| Turbidity / Discharge Standard | Comply with TPDES Construction General Permit (TXR150000) effluent limits. Discharge must not cause or contribute to violations of Texas Surface Water Quality Standards in receiving streams. |
| SWPPP | |
| SWPPP / Local Plan Required | Yes — Stormwater Pollution Prevention Plan (SWPPP) per TPDES TXR150000 |
| PE Stamp Required | No |
| Inspections | |
| Inspection Requirements | Williamson County Road and Bridge Engineering conducts drainage inspections for permitted projects in unincorporated areas. Required stages: pre-construction, drainage infrastructure installation, and final acceptance. Schedule inspections well in advance given the volume of active construction. Projects in the Edwards Aquifer Recharge Zone may require TCEQ-level inspections. |
| Inspector Qualification | No county-specific erosion control inspector certification beyond TPDES requirements. TPDES CGP requires qualified personnel to conduct site inspections at minimum every 14 calendar days and within 24 hours of any qualifying storm event (≥0.5 inches). |
| Design & Zones | |
| Local Design Manual | Williamson County Drainage Criteria Manual |
| Special Overlay Zones | Edwards Aquifer Recharge Zone, FEMA Special Flood Hazard Area (SFHA), Regulated Waterway / Creek Corridor Buffer |