River Authority Wastewater Treatment Plant Expansion Update

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River Authority's Martinez IV Wastewater Treatment Plant

The San Antonio River Authority (River Authority) is a full-service wastewater utility provider serving a portion of northeast Bexar County since 1966. Over the years, we have grown to help provide utilities assistance to communities throughout Wilson, Karnes, and Goliad counties as well.

Read along as we share more info about our wastewater treatment plants (WWTP) and the most recent updates as we work on two plant expansions!

River Authority Wastewater Treatment Plants

Today, the River Authority operates and maintains five permitted and active WWTP. Fun fact, all but one River Authority WWTP is named after the creek the treated wastewater is discharged into. The plant names are Salitrillo, Upper Martinez, Martinez II, Martinez IV, and First Responders Academy. These plants, located in East Bexar County, utilize the latest technology to produce a high-quality effluent to preserve the ecosystems into which the effluent is returned. Effluent is wastewater treated or untreated that flows out of a treatment plant, sewer, or industry outfall. Combined, the River Authority WWTP plants have a capacity of over 13.59 million gallons per day (MGD)!

Salitrillo and Martinez IV Wastewater Treatment Plant Expansions

Salitrillo Wastewater Treatment Plant

Currently, two WWTPs are in the process of undergoing plant expansions. Plant expansions assist in servicing and updating our treatment systems, system administration, and operation and maintenance. Expansions are funded by connection fees, interest income on utilities funds, and uniform user rate charges.

The Salitrillo WWTP located in Converse, Texas, is the River Authority’s most senior plant opened in 1966. The plant is currently permitted at 5.83 million gallons per day, with an average daily flow of approximately 4.86 MGD. This plant will be expanded to 7.33 MGD to accommodate expected development in the area. This will be a progressive design build project and is anticipated to be completed by 2022. Presently, this project is being contracted and is estimated to cost $25 million.

The Martinez IV WWTP located in St. Hedwig, Texas, is the River Authority’s newest WWTP, opened in April 2019. Not only is it the newest, but the plant received a Silver Envision Rating from the Institute of Sustainable Infrastructure. The plant serves 2,200 customers and is permitted for 0.25 MGD. Due to the unexpected rapid development in the area, the WWTP is already near its capacity and needs an expansion. Currently, the design team is assessing the level of expansion needed and the cost.

Request a tour or presentation!

River Authority staff conduct a wastewater treatment plant tour.

As these projects progress, you can look forward to detailed updates in our Utilities newsletter, The Clarifier. You can also request a presentation by a River Authority staff member to learn more about our current projects and initiatives or you can also request a tour of one of our WWTP from our Utilities team. There is also a special tour of the Martinez II WWTP as part of the 2021 River Symposium!

Related Articles

Alerts

Park Closure: Safety Notice

Safety Notice: The Lower River Access areas at Helton Nature Park and Graytown Park have been closed due to rising waters and potential flood risk.

Stay Weather‑Aware

Rain is in the forecast for our are starting Tuesday, June 2 until later this week. Heavy rains in short time spans may result in high water on roads and temporary closures at low water crossings.

Before heading out, residents are encouraged to check SARiverFlood.org or their local county flood website for real‑time roadway conditions:

These sites provide up‑to‑date information from flood‑monitoring sensors across the region. Real‑time updates are available 24/7 to help you stay informed as conditions change.

Please use caution when traveling and plan routes accordingly.

San Pedro Creek Culture Park

The east bank trail along San Pedro Creek will be temporarily closed between the upper trail at Cameron St. and the lower trail at two access points.

Closure details:

  • The first closure will impact the connector from the upper trail near West Houston St. to the south lower San Pedro Creek trail.
  • Once work at this location is complete and the trail reopens, construction will shift to the second closure area between the upper and lower trails on the opposite side of the green space.

Please follow posted signage and plan alternate routes. We appreciate your patience as this work is completed.

Closed areas around San Pedro Creek Culture Park

Trail Closure Alert – Calder Alley, San Pedro Creek

Maintenance work will be done in Calder Alley starting Wednesday, September 18, 2025.

  • Trails will remain open during this work.
  • One bench at a time will be temporarily barricaded while improvements are completed.
  • There may be occasional contractor pickups in the area.

We appreciate your patience as we continue to maintain and improve San Pedro Creek for all to enjoy!

SASPAMCO Paddling Trail

The SASPAMCO paddling trail is open from River Crossing Park to Helton Nature Park.
*Please Note: Paddling Trail from Helton Nature Park to HWY 97 is still closed due to blockages. 

SASPAMCO Paddling Trail Temporarily Closed

Staff have removed two large log jams just downstream of Helton Nature Park, keeping the southern portion of the SASPAMCO Paddling Trail temporarily closed. Staff are working to contact adjacent landowners to support a land-based removal solution.

Goliad Paddling Trail Alert

NOTICE: HWY 59 Landing Site Closed

Due to TxDOT construction on the HWY 59 Bridge, the HWY 59 landing site is closed until further notice. However, the Goliad Paddling Trail remains open, and paddlers can still access the river at the Riverdale, Ferry Street, and Goliad State Park landings.

Please plan accordingly and check back for updates.

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