Joint Regulatory Plan Review

• Develop population and demand projections: This task will provide estimated population and water supply needs for Austin, Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery, Waller, Wharton counties. This analysis will be grounded with the latest 2020 census data and will develop updated population and water demand projections through 2100. Population estimates are being coordinated with the Texas Water Development Board so that they can be adapted for the 2026 Region H Water Plan.

• Conduct alternative water supply assessment: The District’s mission to prevent future subsidence is achieved through the use of alternative water supplies (water resources that, when developed, do not contribute to subsidence), which is currently sourced primarily from treated surface water. This task will examine the availability of additional alternative water supplies and advanced water development methods, including frontier resources such as seawater desalination and reclaimed water supply.
  • Deliverable: Alternative Water Supply Availability Report

• Develop the Gulf Coast Land Subsidence and Groundwater Flow Model: The District is working with the U. S. Geological Survey (USGS) and the Texas Water Development Board to develop the Gulf Coast Land Subsidence and Groundwater Flow (GULF)-2023 model. The GULF-2023 model will simulate the impacts of groundwater use on aquifer water levels and land subsidence. The model area extends from Washington County to Newton County and is being developed for use as a regional tool for planning efforts related to the Groundwater Management Area 14 in addition to the Joint Regulatory Plan Review.
  • Deliverables:
    • Estimation of Historical Pumping and Development of MODFLOW Well Package for Northern Part of the Gulf Coast Aquifer in Texas, 1900 to 2018
    • Hydrogeology, Land-Surface Subsidence, and Documentation of the Gulf Coast Land Subsidence and Groundwater-Flow (GULF) Model, Southeast Texas, 1897–2018 

• Update Analytical Subsidence Models (PRESS Models): The District has historically used an analytical computer model to predict land subsidence caused by pumpage of groundwater, also known as the PRESS (Predictions Relating Effective Stress and Subsidence) model. The PRESS model was adapted for use by the Harris-Galveston Subsidence District in 1978. The PRESS models are legacy models in the District that are focused at 26 specific locations throughout Harris, Galveston, and Fort Bend counties. For this study, the 26 PRESS models used in the 2013 Regulatory Plan Update will be updated with current data (through 2020) to determine if they will require recalibration for use in the Joint Regulatory Plan Review. Additionally, the use of the new technology within the GULF-2023 model is being evaluated as a potential replacement for the PRESS models.

• Evaluate Regulatory Scenarios: Initially, a “post-audit” of the groundwater flow and subsidence model used for the 2013 Regulatory Plan Update will be conducted. Utilizing the information gained from the post-audit, a number of regulatory scenarios to examine variables that are likely to drive regulatory decision-making, such as conversion timelines, regulatory boundaries, drought impacts, use of groundwater credits, and impacts of groundwater regulation (or lack thereof) in adjacent counties.
  • Deliverable: Post Audit of the 2013 Regulatory Plan

Key Schedule Milestones

• Contractor procurement and scope development – Completed December 2019.
• Overall project schedule:
  • Population Projections, Alternative Water Supply Evaluation, Groundwater Models Development – These tasks are underway and scheduled for completion in 2021 and 2022. Preliminary results will be presented to the public at Stakeholder Workshops.
  • Evaluate Regulatory Scenarios – Anticipate initiating in Q1-2023
  • Publish results of Joint Regulatory Plan Review – Anticipate completion in Q4-2024
• Stakeholder Meetings – Stakeholder meetings will be held at the Harris-Galveston Subsidence District to present preliminary results and receive input from stakeholders. Meeting notices will be posted on the website and sent out via mailing list.