Impact on Water Wells

Overview

The Canyon Ranch wastewater permit allows treated effluent to be discharged into a karst landscape that feeds the Edwards Aquifer. This aquifer supplies drinking water to both public systems and hundreds of private wells in the surrounding communities. Because karst geology allows water — and contaminants — to move rapidly through fractures and voids with little natural filtration, wastewater discharge in this area poses a direct risk to groundwater quality.

This page explains why local wells are vulnerable, what was omitted from the permit application, and how residents who rely on private wells may be affected.

Public Water Supply Well at Risk

Within 1.5 miles of the proposed outfall is a public water supply well operated by Cypress Cove Water Supply Corporation. This well:

• is cemented only from 0 to 42 feet

• has an open borehole from 42 to 200 feet

• serves 731 households in Cypress Cove

• draws from highly vulnerable karst limestone

Because the well is open below 42 feet, contaminants entering fractures or conduits can reach the well rapidly, especially during stormwater infiltration or effluent movement through the subsurface.

Not disclosed in the permit application

Texas wastewater permit applications do not require disclosure of public water supply wells, and the Cypress Cove well was not included in the Canyon Ranch permit application. This omission highlights a regulatory gap that leaves nearby communities at increased risk when wastewater facilities are sited near vulnerable aquifer zones.

Private Wells at Risk

In addition to the public well, there are numerous private wells located close to the Canyon Ranch development and the proposed outfall. These wells draw directly from the Edwards Aquifer and are highly susceptible to contamination from stormwater infiltration, disturbed soils, septic leakage, and treated wastewater entering karst features.

Cross Canyon Ranch

• Just north of the area already affected by stormwater runoff, residents in Cross Country Ranch rely entirely on private wells.

• They have no alternative water service, meaning any contamination event would immediately affect drinking water availability.

Many properties also hold wildlife or agricultural exemptions, making water essential for land management, livestock, and habitat maintenance.

Mystic Shores and Surrounding Areas

Other nearby residents — including many in Mystic Shores — depend on private wells for:

• drinking water

• household use

• irrigation

• livestock watering

• wildlife management

Any change in water quality affects both daily living and land stewardship.

Why Local Wells Are Vulnerable

Most wells in this region are drilled into karst limestone, a geology characterized by:

• fractures

• voids

• conduits

• rapid groundwater movement

• limited natural filtration

In karst terrain:

• contaminants can travel miles in hours

• stormwater infiltration bypasses soil filtration

• effluent can move unpredictably through limestone channels

• shallow cementing provides limited protection

• open boreholes allow direct entry of contaminants

EPA notes that private wells are vulnerable to:

• Microorganisms (E. coli, coliforms)

• Nitrates/nitrites from wastewater and runoff

• Heavy metals from disturbed soils and construction

• Organic chemicals from stormwater and effluent

• Sediment and turbidity from erosion and runoff

TWDB guidance confirms that wells near development, agriculture, or wastewater facilities should be tested regularly.

Permit Disclosure Requirements

Wastewater permit applications require identification of:

• the receiving water body

• outfall location

• effluent characteristics

• Edwards Aquifer protection measures

• buffer zones and land application details

However, Texas wastewater permits do not require applicants to identify public water supply wells or private wells near the outfall. As a result, significant groundwater receptors — including the Cypress Cove public well and dozens of private wells — were not evaluated in the permit review process.

This regulatory gap is especially concerning in karst terrain, where groundwater moves quickly and unpredictably.

Regulatory Concerns

Groundwater protection regulations require heightened review when vulnerable wells are located near a wastewater outfall. Key concerns include:

• rapid contaminant transport through karst

• shallow cementing and open boreholes in local wells

• stormwater infiltration carrying sediment and pollutants

• effluent entering fractures and conduits

• lack of well‑disclosure requirements in permitting

• potential impacts to both private and public water supplies

These concerns warrant additional scrutiny by TCEQ and EPA.

Testing Guidance for Private Well Owners

Residents who rely on private wells may wish to test for:

• Total Coliform / E. coli

• Nitrates + Nitrites

• Heavy metals (arsenic, lead, chromium, cadmium, copper, selenium)

• Total Dissolved Solids (TDS)

• Hardness, alkalinity, chloride, sulfate, fluoride

• Organic indicators (TOC, COD, Oil & Grease)

The nearest certified laboratory is the Edwards Aquifer Research & Data Center (EARDC) in San Marcos.

Take Action

Residents should document:

• changes in water clarity

• unusual odors

• pressure fluctuations

• pump cycling irregularities

• sediment or turbidity spikes

How Far Could Contamination Travel?

Groundwater in the Edwards Aquifer does not move slowly or uniformly. In karst terrain, contaminants can travel miles through fractures, conduits, and underground streams. Dye‑trace studies in the Edwards region have documented groundwater movement of 3–10 miles in a matter of hours during storm events.

For this reason, wells within a 3‑mile radius of the Canyon Ranch outfall should be considered potentially vulnerable, especially during periods of heavy rainfall when stormwater infiltration accelerates groundwater movement.

This includes:

• Cypress Cove

• Cross Canyon Ranch

• Mystic Shores

• surrounding private wells