Texas

Buying Land in Mason County, Texas

Mason County -- seat Mason, in the granite hills of the Llano Uplift -- sits entirely inside a single groundwater district built around an aquifer with a genuine, documented water-quality wrinkle, and it's the only county in Texas where the state gemstone occurs naturally. Its own subdivision rules also set a materially higher platting threshold than the statewide default.

One Groundwater District Covers the Entire County

Generally favorable

Mason County lies entirely within the Hickory Underground Water Conservation District No. 1 (HUWCD1), created in 1982 following a district-wide election that passed with 94% voter approval across Concho, Kimble, Mason, McCulloch, Menard, and San Saba Counties. The district covers roughly 1.7 million acres and manages the Hickory Aquifer, the primary water source for Mason and several neighboring counties -- a real, active, and long-running local regulator rather than an unregulated rule-of-capture county. Confirm current well-permitting rules directly with HUWCD1 ((325) 597-2785) before drilling.

The Hickory Aquifer Carries a Real, Named Water-Quality Concern

Case-by-case / verify locally

The Hickory Aquifer is documented as one of the Texas aquifers most affected by naturally occurring radionuclides -- radium leaching from the Precambrian granite of the Llano Uplift, along with its radon decay product -- at levels that have exceeded the EPA's combined-radium drinking-water standard at specific public water systems drawing on this aquifer elsewhere in the district. This research did not find parcel-level radium data specific to Mason County wells, but given that the underlying geology is the same granite the county sits on, a water test for radionuclides is a genuinely worthwhile step before relying on a private well here, not a generic precaution.

Texas's Only Topaz County -- And Access Has Tightened

Could not confirm

Blue topaz has been the official Texas state gemstone since 1969, and Mason County is the only place in Texas it's found in nature, weathering out of granite outcrops and accumulating in alluvial gravels along Comanche Creek and its tributaries near Streeter, Grit, and Katemcy. All of it is on private ranch land -- access has always required a ranch owner's permission or a fee -- and this research found that the county's best-known fee-access ranch for gem hunting stopped allowing access in 2023, so anyone buying with rockhounding or tourism-adjacent plans in mind should check current, specific access arrangements rather than assuming past availability continues.

Groundwater: a single district, a documented aquifer decline, and a real radium question

Mason County is unusual among the counties in this research in that its entire land area, not just part of it, falls under one Groundwater Conservation District: the Hickory Underground Water Conservation District No. 1, created by the Texas Water Commission in 1982 after voters across Concho, Kimble, Mason, McCulloch, Menard, and San Saba Counties approved its formation by a 94% margin. The district spans roughly 1.7 million acres and centers on the Hickory Aquifer, which supplies irrigation, public water systems, industry, livestock, and domestic wells across the region -- but the district's own materials also document real water-level declines in the aquifer's outcrop areas where heavy irrigation pumping has occurred, and note that faulting within the aquifer complicates predicting well depth and yield from one property to the next.

There's also a water-quality dimension worth taking seriously and not treating as boilerplate: the Hickory Aquifer is specifically named in Texas drinking-water research as one of the aquifers most affected by naturally occurring radionuclides, because the Precambrian granite of the Llano Uplift that the aquifer sits within contains radium, which decays into radon gas in groundwater. Combined radium levels at a Hickory-Aquifer-dependent public water utility elsewhere in the district's service area have been documented at roughly 13 times the EPA's maximum contaminant level in a recent test -- a real, checkable example of what this aquifer can produce, even though this research did not find parcel-specific radium data for Mason County wells themselves. Given the shared geology, a radionuclide test is a reasonable, specific step before relying on a private well here, and worth budgeting for if a treatment system turns out to be needed.

The only topaz county in Texas -- and a subdivision rule set higher than the state default

Blue topaz became the official Texas state gemstone by legislative act in 1969, and Mason County is the only place in the state where it occurs naturally, weathering out of Precambrian granite outcrops and settling into alluvial gravels along Comanche Creek and its tributaries, concentrated around the Streeter, Grit, and Katemcy areas. All of that land is private ranch property, and access has always run through the landowner -- either a standing permission arrangement or a per-day fee at a handful of ranches known for allowing it. That access base has narrowed recently: this research found that the last well-known fee-access ranch for gem hunting discontinued the practice in 2023, which is worth knowing both for anyone drawn to the county partly for its rockhounding reputation and as a reminder that this kind of informal recreational-access arrangement can end without much notice.

On the regulatory side, Mason County has adopted its own written Subdivision Regulations, most recently revised in October 2022, and those regulations set a 50-acre threshold below which a division of land triggers platting and road-standard requirements -- a materially higher bar than the 10-acre exemption that applies as the statewide default under Texas Local Government Code Chapter 232 absent a county's own stricter rule. In practice, that means a division of Mason County land into parcels smaller than 50 acres is more likely to require formal platting than the same division would in a county that has not adopted its own subdivision order. Confirm current requirements directly with the County Clerk's office before assuming a smaller acreage split is exempt.

What we could and couldn't confirm

HUWCD1's 1982 creation, 94% approval vote, six-county coverage, and roughly 1.7 million-acre extent are drawn from the district's own website and the Texas Alliance of Groundwater Districts. The Hickory Aquifer's radionuclide profile is a documented, aquifer-wide characteristic per TCEQ and reporting on a specific neighboring-county utility (Millersview-Doole, serving Concho County); this research did not locate Mason-County-specific well or public-system radium test results, so that comparison is presented as regional context, not a Mason County measurement. Topaz location and access details are drawn from a Gemological Institute of America feature and Texas Standard reporting. Mason County's 50-acre platting exemption is drawn from the county's own posted Subdivision Regulations document.

Verify directly with: Hickory UWCD1 directly for well permitting and any radionuclide monitoring data specific to a target well, the Mason County Clerk for current subdivision regulations, and a private lab for radionuclide testing before relying on a well

Who to Call Before Buying Land in Mason County

Mason County has no general zoning ordinance for its unincorporated area, consistent with the statewide default -- it regulates land division through its own Subdivision Regulations instead. This research did not confirm whether Mason County holds TCEQ OSSF authorized-agent status; TCEQ Region 8 (San Angelo) is listed as the fallback contact pending direct confirmation.

Wells / Private Water

Hickory Underground Water Conservation District No. 1

Well registration, permitting, and water-quality guidance for parcels in Mason, Concho, Kimble, McCulloch, Menard, or San Saba County.

Phone: (325) 597-2785Email: hickoryuwcd@yahoo.comOfficial website →

Subdivision & Land Development

Mason County Clerk / Commissioners Court

Current subdivision regulations, the county's 50-acre platting exemption threshold, and plat filing.

Phone: (325) 347-5253Official website →

Assessor / Property Tax

Mason County Appraisal District

Assessed value, property tax, and agricultural (ag/wildlife) valuation questions for a specific parcel.

Phone: (325) 347-5989Official website →

Environmental Health

TCEQ Region 8 -- San Angelo

On-site sewage facility (septic) permitting, absent a confirmed county authorized-agent arrangement.

Official website →

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Sources

Hickory UWCD # 1: Groundwater Management Plan Adopted 2024 — Hickory Underground Water Conservation District No. 1 (accessed 2026-09)
About Hickory UWCD No. 1 — Hickory Underground Water Conservation District No. 1 (accessed 2026-09)
Hickory UWCD No. 1 — Texas Alliance of Groundwater Districts (accessed 2026-09)
Radionuclides in Drinking Water — Texas Commission on Environmental Quality (TCEQ) (accessed 2026-09)
Permian Basin community seeks fix for radium in its drinking water — Texas Public Radio (accessed 2026-09)
Topaz from Mason County, Texas — Gemological Institute of America (GIA) (accessed 2026-09)
Texas topaz hunters must now find other ways to look for the state gemstone — Texas Standard (accessed 2026-09)
Mason County Subdivision Regulations (Revised 10-03-2022) — Mason County, Texas (accessed 2026-09)
Which TCEQ Region is My County In? — Texas Commission on Environmental Quality (TCEQ) (accessed 2026-09)
Mason CAD -- Official Site — Mason County Appraisal District (accessed 2026-09)

Last reviewed 2026-09