Denton County, TX Environmental Rules: Grading & Drainage (2026)

Grading and drainage in Denton County are regulated by city development ordinances and county standards for unincorporated areas. A grading permit is required for most earth-moving activities that alter the natural drainage pattern of a property. Cities within the county require a drainage study or analysis for residential and commercial developments to demonstrate that post-development runoff does not exceed pre-development rates. The City of Denton requires developments to maintain a positive drainage slope of at least 2 percent away from building foundations for a minimum of 10 feet. Fill material must be compacted to at least 95 percent of standard Proctor density when supporting structures. Cut and fill slopes must not exceed a 3:1 ratio unless engineered retaining walls are used. Retaining walls over 4 feet in exposed height require engineered plans and a building permit. Denton County drainage easements must remain clear of structures, fences, and obstructions that could impede stormwater flow. Property owners may not alter drainage easements or redirect stormwater onto neighboring properties. Cities such as Flower Mound and Corinth require lot-to-lot drainage analyses showing that grading does not adversely affect adjacent properties. In unincorporated areas, the Denton County Engineering Department reviews grading plans for subdivisions and commercial developments to ensure compliance with county drainage criteria.