(a) A county, district, or authority may take any necessary or proper action to comply with the requirements of the stormwater permitting program under the national pollutant discharge elimination system (Section 402, Federal Water Pollution Control Act (33 U.S.C. § 1342)), including:
(1) developing and implementing controls to reduce the discharge of pollutants from any conveyance or system of conveyance owned or operated by the county, district, or authority that is designed for collecting or conveying stormwater;
(2) developing, implementing, and enforcing stormwater management guidelines, design criteria, or rules to reduce the discharge of pollutants into any conveyance or system of conveyance owned or operated by the county, district, or authority that is designed for collecting or conveying stormwater;
(3) assisting residents with the proper management of used oil and toxic materials, including the holding of household hazardous waste collection events;
(4) developing and providing educational tools and activities designed to reduce or lead to the reduction of the discharge of pollutants into stormwater; and
(5) assessing reasonable charges to fund the implementation, administration, and operation of the stormwater permitting program as necessary to comply with federal or state program requirements.
(b) Notwithstanding Subsection (a)(5), a county, district, or authority may not assess a charge against property that is:
(1) exempt from ad valorem taxation; or
(2) subject to an assessment for the same purpose by another entity.