In rural and semi-rural areas across Texas, Oklahoma, New Mexico, and Colorado, one of the biggest challenges in planning a new subdivision isn’t about roads or lot layout; it’s about water. Before a single home is built, developers must prove that the project can sustain a long-term, reliable water supply. That’s where a Groundwater Availability Certification (GAC) comes in.

A GAC plays a critical role in subdivision development, ensuring there’s enough groundwater to support every part of the community, from residential use and landscaping to fire protection and irrigation. Without this certification, projects can face delays, costly redesigns, or even permit denials.

What Is a Groundwater Availability Certification?

A Groundwater Availability Certification (sometimes called a hydrogeological or water supply assessment) is a formal evaluation that determines whether sufficient groundwater exists to meet the needs of a proposed subdivision. It’s often required by county and state agencies as part of the subdivision permitting process, especially in areas without access to municipal or regional water systems.

The process involves studying the underlying aquifers, drilling test wells, and analyzing both the quantity and quality of available water. The goal is to confirm that the development won’t overdraw local groundwater resources or leave future homeowners facing water shortages down the line.

For example, in Texas, counties operating under Texas Local Government Code § 232.0032 must require a GAC before approving plats for subdivisions that plan to use groundwater as their primary source. This ensures every lot has access to a sustainable water supply for development, verified by scientific data rather than assumption.

Why GAC Matters for Developers

A GAC isn’t just a permitting formality; it’s a safeguard for both developers and buyers. Here’s why it matters:

• Prevents costly surprises: Early testing confirms whether the local aquifer can handle the projected water demand, reducing the risk of redesign or drilling new wells later.

• Supports sustainable growth: Groundwater sustainability is a growing priority across the Southwest. Proper certification helps ensure new developments don’t stress local resources or neighboring wells.

• Increases property value and marketability: A certified water source adds long-term value, offering confidence to buyers, lenders, and regulators that the subdivision is built on reliable infrastructure.

• Streamlines approvals: Demonstrating compliance with local subdivision permitting requirements early in the process keeps projects on schedule.

In short, a GAC gives both regulators and developers confidence that a subdivision is planned responsibly, and that its water source can keep up with community needs for decades to come.

What’s Involved in a GAC Assessment

The certification process typically involves a hydrogeological assessment performed by a licensed hydrogeologist or geotechnical consultant. This includes:

• Reviewing local geology and aquifers: Mapping groundwater-bearing formations to understand capacity and flow direction.

• Drilling test wells: Collecting water samples and measuring depth to groundwater.

• Pumping and yield tests: Determining how much water can be sustainably drawn over time.

• Water quality testing: Checking for contaminants, minerals, and overall potability.

• Sustainability modeling: Projecting long-term water availability based on expected usage, recharge rates, and climate conditions.

Depending on local regulations, the process can take 4 to 12 weeks from start to certification. Early coordination with regulatory agencies and engineering teams can help prevent delays in subdivision approval.

How GACs Impact Long-Term Development

Beyond permitting, a GAC shapes how infrastructure is designed. It informs the placement of wells, the sizing of storage tanks, and the design of water distribution systems. In rural or off-grid areas, these decisions directly affect a community’s resilience and maintenance costs.

A well-documented GAC report also provides reassurance to future buyers, proving that the subdivision’s water supply has been vetted and approved by qualified experts. It’s a long-term investment in both the project’s credibility and its sustainability.

Building with Sustainability in Mind

As groundwater demand continues to rise across the Southwest, responsible development depends on careful resource management. Obtaining a GAC isn’t just about compliance—it’s about protecting local aquifers and ensuring future residents have reliable access to clean water.

At Centerline, our team works closely with hydrogeologists, engineers, and regulatory agencies to guide developers through the GAC process, from initial site investigation to final certification.

If you’re planning a new subdivision or rural development project, we can help ensure your water supply is sustainable, compliant, and ready to support long-term growth.

Contact us today to learn more about our geoscience and hydrogeological services.

FAQs

• Is a Groundwater Availability Certification required for all subdivision projects?
  In many jurisdictions, yes, especially if the development relies on private wells or lacks access to a municipal water system. Requirements vary by region, so it’s important to check with local planning authorities.

• How long does it take to obtain a GAC?
  Typically 4–12 weeks, depending on site conditions, local rules, and the scope of the hydrogeological study. Starting early helps prevent delays.

• Does a GAC affect property value or marketability?
  Absolutely. A certified, sustainable water source adds long-term value, improves buyer confidence, and supports smoother property transactions.

• Who conducts a GAC assessment?
  A licensed hydrogeologist or geotechnical consultant typically performs the assessment, which includes test wells, aquifer analysis, and water quality testing.