Environmental Rules in San Marcos, TX (2026)
5 verified environmental rules for San Marcos, Texas, sourced directly from the municipal code and official government pages.
Verified from official government sources
Stormwater Management
San Marcos bans illicit discharges into its storm sewer system and funds drainage work through a monthly stormwater utility fee on every property.
San Marcos Stormwater Discharge Ban
Some RestrictionsSan Marcos Code of Ordinances § 86.526
Illicit discharges are prohibited into the MS4 and/or surface water in the state. No person shall release discharges into the MS4 containing any pollutants that cause or contribute to a violation of water quality standards.
Erosion Control
San Marcos requires every construction site to use best management practices controlling sediment, silt, and soil discharges to the municipal storm sewer system under the city's MS4 stormwater ordinance.
San Marcos Construction Stormwater Erosion Control
Some RestrictionsSan Marcos Code of Ordinances § 86.529(a)(1)
All operator(s) of construction activities shall use best management practices to control and reduce the discharge, to the MS4 and to surface water in the state, of sediment, silt, earth, soil, and other material associated with the demolition, clearing, grading, excavation, and other construction activities to the maximum extent practicable under the circumstances.
Flood Zones
San Marcos requires a floodplain development permit for any construction or development in a mapped special flood hazard area before work can begin.
San Marcos Floodplain Development Permit
Some RestrictionsSan Marcos Code of Ordinances § 39.022
A floodplain development permit is required for all proposed construction or other development within regulatory floodplains or other areas of flooding identified by the City of San Marcos to ensure conformance with the provisions of this chapter.
Vehicle Idling Restrictions
San Marcos bans idling a motor vehicle's primary propulsion engine for more than five consecutive minutes when the vehicle isn't moving, citywide and into the ETJ.
San Marcos 5-Minute Idling Limit
Some RestrictionsSec. 34.403
No person shall cause, suffer, allow, or permit the primary propulsion engine of a motor vehicle to idle for more than five consecutive minutes when the motor vehicle is not in motion.
Flood Elevation Requirements
San Marcos requires new construction and substantial improvements in AE, AH, and AO flood zones to elevate the lowest floor two feet above base flood elevation.
San Marcos 2-Foot Freeboard Rule
Some RestrictionsSan Marcos City Code Sec. 39.043(2)a
All new construction or substantial improvements of residential structures must have the lowest floor (including basement) elevated to two feet above the base flood elevation.