31 Tex. Admin. Code § 357.32 - Water Supply Analysis

(a) RWPGs shall evaluate:

(1) source water Availability during Drought of Record conditions; and

(2) Existing Water Supplies that are legally and physically available to each WUG and WWP within the RWPA for use during the Drought of Record.

(b) Evaluations shall consider surface water and groundwater data from the State Water Plan, existing water rights, contracts and option agreements relating to water rights, other planning and water supply studies, and analysis of water supplies existing in and available to the RWPA during Drought of Record conditions.

(c) For surface water supply analyses, RWPGs shall use most current Water Availability Models from the Commission to evaluate the adequacy of surface water supplies. As the default approach for evaluating existing supplies, RWPGs shall assume full utilization of existing water rights and no return flows when using Water Availability Models. RWPGs may use better, more representative, water availability modeling assumptions or better site-specific information with written approval from the EA. Information available from the Commission shall be incorporated by RWPGs unless better site-specific information is available and approved in writing by the EA.

(1) Evaluation of existing stored surface water available during Drought of Record conditions shall be based on Firm Yield as defined in § 357.10 of this title (relating to Definitions and Acronyms). The analysis may be based on justified operational procedures other than Firm Yield. The EA shall consider a written request from an RWPG to use procedures other than Firm Yield.

(2) Evaluation of existing run of river surface water available for municipal WUGs during Drought of Record conditions shall be based on the minimum monthly diversion amounts that are available 100 percent of the time, if those run of river supplies are the only supply for the municipal WUG.

(d) RWPGs shall use modeled available groundwater volumes for groundwater Availability, as issued by the EA, and incorporate such information in its RWP unless no modeled available groundwater volumes are provided. Groundwater Availability used in the RWP must be consistent with the desired future conditions as of the most recent deadline for the Board to adopt the State Water Plan or, at the discretion of the RWPG, established subsequent to the adoption of the most recent State Water Plan.

(1) An RWP is consistent with a desired future condition if the groundwater Availability amount in the RWP and on which an Existing Water Supply or recommended WMS relies does not exceed the modeled available groundwater amount associated with the desired future condition for the relevant aquifers, in accordance with paragraph (2) of this subsection or as modified by paragraph (3) of this subsection, if applicable. The desired future condition must be either the desired future condition adopted as of the most recent deadline for the Board to adopt the State Water Plan or, at the option of the RWPG, a desired future condition adopted on a subsequent date.

(2) If no groundwater conservation district exists within the RWPA, then the RWPG shall determine the Availability of groundwater for regional planning purposes. The Board shall review and consider approving the RWPG-Estimated Groundwater Availability, prior to inclusion in the IPP, including determining if the estimate is physically compatible with the desired future conditions for relevant aquifers in groundwater conservation districts in the co-located groundwater management area or areas. The EA shall use the Board's groundwater availability models as appropriate to conduct the compatibility review.

(3) In RWPAs that have at least one groundwater conservation district, the EA shall consider a written request from an RWPG to apply a MAG Peak Factor in the form of a percentage (e.g., greater than 100 percent) applied to the modeled available groundwater value of any particular aquifer-region-county-basin split within the jurisdiction of a groundwater conservation district, or groundwater management area if no groundwater conservation district exists, to allow temporary increases in annual availability for planning purposes. The request must:

(A) Include written approval from the groundwater conservation district, if a groundwater conservation district exists in the particular aquifer-region-county-basin split, and from representatives of the groundwater management area;

(B) Provide the technical basis for the request in sufficient detail to support groundwater conservation district, groundwater management area, and EA evaluation; and

(C) Document the basis for how the temporary availability increase will not prevent the groundwater conservation district from managing groundwater resources to achieve the desired future condition.

(e) Water supplies based on contracted agreements shall be based on the terms of the contract, which may be assumed to renew upon contract termination if the contract contemplates renewal or extensions.

(f) Evaluation results shall be reported by WUG in accordance with § 357.31(a) of this title (relating to Projected Population and Water Demands) and MWP in accordance with § 357.31(b) of this title.

Notes

31 Tex. Admin. Code § 357.32

The provisions of this §357.32 adopted to be effective August 12, 2012, 37 TexReg 5797; Amended by Texas Register, Volume 41, Number 49, December 2, 2016, TexReg 9622, eff. 12/8/2016; Amended by Texas Register, Volume 43, Number 14, April 6, 2018, TexReg 2164, eff. 4/11/2018; Amended by Texas Register, Volume 47, Number 17, April 29, 2022, TexReg 2539, eff. 5/1/2022