Stormwater Impact from Canyon Ranch Development 

Overview

Stormwater runoff from the Canyon Ranch development is already affecting Mystic Shores properties — before the wastewater treatment plant becomes operational. Multiple rain events in June produced visible flooding, pooling, silt deposition, and drainage impacts on neighboring lots. These early signs indicate inadequate or missing Best Management Practices (BMPs) and raise concerns about long‑term property, septic, and environmental impacts once treated effluent is added to the same flow paths.

Storm Events Summary (June 2026)

Residents documented stormwater impacts during light rains prior to June 15, including flooding on Lot 1403, pooling on Lot 1452R, and silt deposition in the Rosinweed culverts. On June 15, a 2.5‑inch rain produced even heavier runoff, but the siltation in the Rosinweed culverts was already present beforehand. 

Regulatory Update

TCEQ has scheduled an on‑site inspection before July 10 to evaluate stormwater controls at Canyon Ranch. This inspection was initiated after the Comal County Engineer’s Office forwarded resident documentation and concerns to TCEQ.

The findings will help determine whether required BMPs were installed, maintained, and functioning during recent rain events.

A report has also been submitted to the U.S. Environmental Protection Agency (EPA) for review. This report includes resident documentation of stormwater runoff, silt deposition, and drainage impacts observed in June. 

Residents are encouraged to continue documenting stormwater runoff, pooling, erosion, and silt deposition.

Regulatory Concerns

Several regulatory issues may be implicated by the stormwater runoff entering Mystic Shores from the Canyon Ranch development:

• Texas Water Code §11.086 prohibits diverting or impounding natural drainage in a way that damages neighboring property.

• Stormwater Pollution Prevention Plan (SWPPP) requirements may not be met if BMPs are missing, ineffective, or not maintained.

• Sediment transport into Rosinweed culverts indicates disturbed soils and inadequate erosion controls.

• Retention pond bypass (as observed by residents) may signal improper grading or failed stormwater routing.

• Drainage impacts on Lots 1403 and 1452R raise concerns about septic system interference, foundation stability, and mosquito breeding conditions.

• Downstream impacts to Devils Hollow and the Nature Preserve may occur once treated effluent is added to the same flow paths.

These concerns highlight the need for thorough review during TCEQ’s upcoming inspection.

Two Stormwater Streams Enter Mystic Shores

Homes are now being constructed in Canyon Ranch, and new structures are appearing quickly. Resident observations indicate that stormwater is bypassing the retention pond and flowing directly toward Lot 1403, increasing runoff volume and velocity. 

Stream 1 — Shake → Mystic Canyon → Wright

This stream originates on the Canyon Ranch property and flows directly into Mystic Shores:

• Lot 1403 (Shake):

  • Severe flooding during light rains

  • Erosion and soil displacement

• Crossing Mystic Canyon:

  • Water moves through culverts beneath Mystic Canyon

  • Flow continues downslope toward neighboring properties

• Lot 1452R (Wright):

  • Water flows through the center of the property

  • Pooling and stagnant zones ideal for mosquito breeding

  • Septic system at risk during heavy rains + wastewater flow

  • Potential foundation stability concerns

  • Stagnant areas visible in photos and resident documentation

• Beyond

  • The water then flows along the back of 20+ lots.

This stream represents the primary flow path that will carry treated effluent once the wastewater plant becomes operational.

Residents have observed that the stormwater retention pond appears to be bypassed during rain events, with runoff flowing directly toward Lot 1403. This observation will be important for TCEQ’s upcoming inspection. 

Stream 2 — Rosinweed Culverts

A second stormwater stream enters Mystic Shores through Lots 1412 and 1413, carrying runoff into the Rosinweed culverts.

Silt deposition in these culverts was documented before the June 15 storm, indicating that sediment movement is occurring even during light‑rain events.

The June 15 rain added additional runoff volume but did not create the initial siltation — the problem was already present.

These observations suggest:

• disturbed soils on the Canyon Ranch side

• inadequate or missing BMPs

• chronic sediment transport

• a persistent stormwater pathway that predates heavier rainfall

This stream shows that stormwater impacts are ongoing, not isolated to a single storm.

Why Light‑Rain Runoff Is a Red Flag

Stormwater runoff during small storms is one of the strongest indicators of failed or missing BMPs. Properly installed erosion controls should prevent visible sediment movement during low‑intensity rainfall.

Runoff during light rains suggests:

• inadequate perimeter controls

• disturbed soils left unprotected

• missing silt fencing or check dams

• insufficient slope stabilization

• potential violations of TPDES stormwater requirements

If BMPs cannot control runoff during light rains and a 2.5‑inch storm, they will not control runoff once 300,000 gallons/day of treated effluent is added to the same flow paths.

Property Impacts

Lot 1403 (Shake)

• Flooding during light rains

• Erosion and soil displacement

Lot 1452R (Wright)

• Water flowing through the center of the property

• Pooling and stagnant zones

• Mosquito breeding concerns

• Septic system vulnerability

• Foundation stability concerns

• Stagnant water visible in multiple storm events

These impacts occurred before the wastewater treatment plant is operational.

Environmental Concerns

• Sediment transport toward downstream drainage features

• Increased nutrient loading once effluent is added

• Potential impacts to Devils Hollow and the Nature Preserve

• Long‑term risks to wells and karst limestone features

• Increased mosquito activity in stagnant zones

Stormwater is the first warning sign of how the watershed will respond once treated effluent enters the same flow paths.

What We Are Asking For

We are asking TCEQ and Comal County to:

• Conduct a full on‑site inspection of stormwater controls

• Verify BMP installation and maintenance

• Require immediate stabilization of disturbed soils

• Review drainage impacts on neighboring properties

• Ensure stormwater controls are functioning before wastewater discharge begins

Take Action

Stormwater impacts are already visible. Before wastewater is added to these same flow paths, we need stronger oversight.

You can help by:

• Continuing to document stormwater runoff, pooling, and silt deposition

• Sharing observations with county or state officials as needed

• Staying informed as TCEQ completes its inspection

Photo & Video Documentation

Drone Footage 

The drone videos below were shot to document the stormwater flooding. Note that these were shot BEFORE the 2.5" rain we received early on 6/15/2026. About the 1:50 minute mark of the first video, note the amount of silt accumulating in the culverts on Mystic Canyon. With more substantial rainfall, these could overflow and flood the street. Lots 1403 and 1452R are shown below. There is a home on 1452R though that is not shown out of respect for the owners' privacy. The water flows through and pools in the center of these lots.

6/15/2026 - Lot 1403 video at ground level following 2.5" of rain. At 4:30 the view shifts to culverts emptying onto Lot 1452R.

6/8/2026 - Culverts are filling with silt from the construction at Canyon Ranch (aka Juniper Ranch). Complaints were registered with Jen Crownover, County Commissioner and Comal County Engineer's Office on 6/11/2026.

6/7/2026 - We have had less than three inches of rain over the last few weeks. Trees are dying on lot 1403 from the runoff. All of these photos were taken before we had any significant rainfall.

Stormwater is the first warning sign. Once treated effluent is added to this same flow path, the impacts will only intensify.