(a) In this section, “water quality protection” may be achieved by:
(1) maintaining background levels of water quality in waterways; or
(2) capturing and retaining the first 1.5 inches of rainfall from developed areas.
(b) For the purpose of Subsection (a)(1), “maintaining background levels of water quality in waterways” means maintaining background levels of water quality in waterways comparable to those levels which existed prior to new development as measured by the following constituents: total suspended solids, total phosphorus, total nitrogen, and chemical and biochemical oxygen demand. Background levels shall be established either from sufficient data collected from water quality monitoring at one or more sites located within the area designated as a water quality protection zone or, if such data are unavailable, from calculations performed and certified by a registered professional engineer utilizing the concepts and data from the National Urban Runoff Program (NURP) Study or other studies approved by the Texas Natural Resource Conservation Commission (commission) for the constituents resulting from average annual runoff, until such data collected at the site are available. Background levels for undeveloped sites shall be verified based on monitoring results from other areas of property within the zone prior to its development. The monitoring shall consist of a minimum of one stage (flow) composite sample for at least four storm events of one-half inch or more of rainfall that occur at least one month apart. Monitoring of the four constituents shall be determined by monitoring at four or more locations where runoff occurs. A minimum of four sample events per year for each location for rainfall events greater than one-half inch shall be taken. Monitoring shall occur for three consecutive years after each phase of development occurs within the Water Quality Protection Zone. Each new phase of development, including associated best management practices, will require monitoring for a three-year period. The results of the monitoring and a description of the best management practices being used throughout the zone shall be summarized in a technical report and submitted to the commission no later than April 1 of each calendar year during development of the property, although the commission may determine that monitoring is no longer required. The commission shall review the technical report. If the performance monitoring and best management practices indicate that background levels were not maintained during the previous year, the owner or developer of land within the water quality protection zone shall:
(1) modify water quality plans developed under this section for future phases of development in the water quality protection zone to the extent reasonably feasible and practical; and
(2) modify operational and maintenance practices in existing phases of the water quality protection zone to the extent reasonably feasible and practical.

Water quality monitoring shall not be required in areas using the methodology described by Subsection (a)(2).
(c) This section applies only to those areas within the extraterritorial jurisdiction, outside the full-purpose corporate limits of a municipality with a population greater than 10,000, and in which the municipality either:
(1) has enacted or attempted to enforce three or more ordinances or amendments thereto attempting to regulate water quality or control or abate water pollution in the area within the five years preceding the effective date of this Act, whether or not such ordinances or amendments were legally effective upon the area; or
(2) enacts or attempts to enforce three or more ordinances or amendments thereto attempting to regulate water quality or control or abate water pollution in the area in any five-year period, whether or not such ordinances or amendments are legally effective upon the area.
(d) The owner or owners of a contiguous tract of land in excess of 1,000 acres that is located within an area subject to this section may designate the tract as a “water quality protection zone.” Upon prior approval of the Commission, the owner of a contiguous tract of land containing less than 1,000 acres, but not less than 500 acres, that is located within an area subject to this section may also designate the tract as a “water quality protection zone.” The tract shall be deemed contiguous if all of its parts are physically adjacent, without regard to easements, rights-of-way, roads, streambeds, and public or quasi-public land, or it is part of an integrated development under common ownership or control. The purpose of a water quality protection zone is to provide for the consistent protection of water quality in the zone without imposing undue regulatory uncertainty on owners of land in the zone.
(e) A water quality protection zone designated under this section shall be described by metes and bounds or other adequate legal description. The designation shall include a general description of the proposed land uses within the zone, a water quality plan for the zone, and a general description of the water quality facilities and infrastructure to be constructed for water quality protection in the zone.
(f) Creation of a water quality protection zone shall become immediately effective upon recordation of the designation in the deed records of the county in which the land is located. The designation shall be signed by the owner or owners of the land, and notice of such filing shall be given to the city clerk of the municipality within whose extraterritorial jurisdiction the zone is located and the clerk of the county in which the property is located.
(g) A water quality protection zone designation may be amended and a designation may specify the party or parties authorized to execute amendments to the zone designation and the zone’s water quality plan. Land may be added to or excluded from a zone by amending the zone designation. An amendment to a zone designation adding land to or excluding land from a zone must describe the boundaries of the zone as enlarged or reduced by metes and bounds or other adequate legal description. An amendment to a zone designation is effective on its filing in the deed records of the county in which the land is located. On application by all owners of land in a zone, or by each party authorized by the zone designation or an amendment to the zone designation to amend the zone designation, the commission may terminate a zone on reasonable terms and conditions specified by the commission.
(h) The water quality plan for a zone, including the determination of background levels of water quality, shall be signed and sealed by a registered professional engineer acknowledging that the plan is designed to achieve the water quality protection standard defined in this section. On recordation in the deed records, the water quality plan shall be submitted to and accepted by the commission for approval, and the commission shall accept and approve the plan unless the commission finds that implementation of the plan will not reasonably attain the water quality protection as defined in this section. A water quality plan may be amended from time to time on filing with the commission, and all such amendments shall be accepted by the commission unless there is a finding that the amendment will impair the attainment of water quality protection as defined in this section. The commission shall adopt and assess reasonable and necessary fees adequate to recover the costs of the commission in administering this section. The commission’s review and approval of a water quality plan shall be performed by the commission staff that is responsible for reviewing pollution abatement plans in the county where the zone is located. The review and approval of the plan or any amendment to the plan shall be completed within 120 days of the date it is filed with the commission. A public hearing on the plan shall not be required, and acceptance, review, and approval of the water quality plan or water quality protection zone shall not be delayed pending the adoption of rules. The commission shall have the burden of proof for the denial of a plan or amendments to a plan, and any such denial shall be appealable to a court of competent jurisdiction. The water quality plan, or any amendment thereto, shall be effective upon recordation of the plan or the amendment in the deed records and shall apply during the period of review and approval by the commission or appeal of the denial of the plan or any amendment. New development under a plan may not proceed until the plan or amendment to the plan, as appropriate, has been approved by the commission.
(i) The water quality plan for a zone shall be a covenant running with the land.
(j) A municipality may not enforce in a zone any of its ordinances, land use ordinances, rules, or requirements including, but not limited to, the abatement of nuisances, pollution control and abatement programs or regulations, water quality ordinances, subdivision requirements, other than technical review and inspections for utilities connecting to a municipally owned water or wastewater system, or any environmental regulations which are inconsistent with the land use plan and the water quality plan or which in any way limit, modify, or impair the ability to implement and operate the water quality plan and the land use plan within the zone as filed; nor shall a municipality collect fees or assessments or exercise powers of eminent domain within a zone until the zone has been annexed for the municipality. A water quality protection zone may be annexed by a municipality only after the installation and completion of 90 percent of all facilities and infrastructure described in the water quality plan for the entire zone as being necessary to carry out such plan or the expiration of 20 years from the date of designation of the zone, whichever occurs first.
(k) Subdivision plats within a water quality protection zone shall be approved by the municipality in whose extraterritorial jurisdiction the zone is located and the commissioners court of the county in which the zone is located if:
(1) the plat complies with the subdivision design regulations of the county; and
(2) the plat is acknowledged by a registered professional engineer stating that the plat is in compliance with the water quality plan within the water quality protection zone.
(l) A water quality protection zone implementing a water quality plan which meets the requirements of this section shall be presumed to satisfy all other state and local requirements for the protection of water quality; provided, however, that:
(1) development in the zone shall comply with all state laws and commission rules regulating water quality which are in effect on the date the zoning is designated; and
(2) nothing in this section shall supersede or interfere with the applicability of water quality measures or regulations adopted by a conservation and reclamation district comprising more than two counties and which apply to the watershed area of a surface lake or surface reservoir that impounds at least 4,000 acre-feet of water.
(m)(1) One or more of the provisions of this section may be waived by the owner or owners of property that is or becomes subject to an agreement entered into after the effective date of this Act between the owner or owners of land within the zone and the municipality. The agreement shall be in writing, and the parties may agree:
(A) to guarantee continuation of the extraterritorial status of the zone and its immunity from annexation by the municipality for a period not to exceed 15 years after the effective date of the agreement;
(B) to authorize certain land uses and development within the zone;
(C) to authorize enforcement by the municipality of certain municipal land use and development regulations within the zone, in the same manner such regulations are enforced within the municipality’s boundaries, as may be agreed by the landowner and the municipality;
(D) to vary any watershed protection regulations;
(E) to authorize or restrict the creation of political subdivisions within the zone; and
(F) to such other terms and considerations the parties consider appropriate, including, but not limited to, the continuation of land uses and zoning after annexation of the zone, the provision of water and wastewater service to the property within the zone, and the waiver or conditional waiver of provisions of this section.
(2) An agreement under this section shall meet the requirements of and have the same force and effect as an agreement entered into pursuant to § 42.046, Local Government Code.
(n) In addition to the requirements of Subsections (a)(1) and (a)(2), the commission may require and enforce additional water quality protection measures to comply with mandatory federal water quality requirements, standards, permit provisions, or regulations.
(o) This section does not apply to an area within the extraterritorial jurisdiction of a municipality with a population greater than 1.3 million that has extended to the extraterritorial jurisdiction of the municipality an ordinance whose purpose is to prevent the pollution of an aquifer which is the sole or principal drinking water source for the municipality.
(p) If a municipality’s action results in part of a zone being located outside the municipality’s extraterritorial jurisdiction, the entire zone is removed from the municipality’s extraterritorial jurisdiction. A zone removed from a municipality’s extraterritorial jurisdiction may not be brought into the municipality’s extraterritorial jurisdiction before the 20th anniversary of the date on which the zone was designated.
(q) In addition to the fees authorized under Subsection (h), the commission shall adopt and assess reasonable and necessary fees adequate to recover the commission’s costs in monitoring water quality associated with water quality protection zones.