The Sunken Gardens Rehabilitation Project will address ongoing erosion and bank stabilization issues, rehabilitate historic masonry walls, improve habitat for endangered salamanders, and better interpret the site through educational panels. The Sunken Gardens is located downstream of the Barton Springs pool spillway, just east of the south lawn of Barton Springs Pool. The project is currently in the preliminary design phase. District 5
Project Update
The Phase 1 Design contract for the Sunken Gardens Rehabilitation Project was executed in June 2024 with the engineering firm, HDR, Inc. The project team will begin data collection in July and August 2024, which includes topographic and tree surveys, environmental resource inventory, geotechnical boring, and cultural resource survey. After completion of the data collection, consultants will begin to develop concept alternatives for the historic wall rehabilitation, drainage outflow design, and bank stabilization. Completion of the Phase 1 Preliminary Design is anticipated in Summer 2025.
Background
Sunken Gardens is the site of one of the four principal springs of Barton Springs and is situated on the south side of the pool. The structure was built in 1937-1939 atop the foundation of an earlier structure, known as the Old Mill, by the National Youth Administration with oversight by architect Delmar Groos. The structure features a series of 12” thick, unreinforced stone masonry walls, ranging in height from 6-12’ tall, which form concentric circles from a primary spring-fed pool. Critical habitat for the endangered Barton Spring and Austin blind salamanders is located at Sunken Gardens. The salamander habitat in the spring pool and stream channel has been compromised by modifications around these natural bodies.
The spring discharges into Barton Creek approximately 500 feet downstream of Barton Springs Pool through an outlet channel connecting the spring to Barton Creek. This outfall channel is experiencing severe erosion that threatens to damage a pedestrian bridge, the historic masonry walls and critical salamander habitat. Habitat rehabilitation at Sunken Gardens, through a combination of reconstruction and restoration, is a conservation measure in the 2013 Barton Springs Pool Habitat Conservation Plan in conjunction with the US Fish and Wildlife permit issued to the City of Austin. In addition, the historic masonry walls which surround the upper tiers of Sunken Garden have been studied and recommended to be repaired in the 2008 Barton Springs Master Plan.
Project Description
This contract will provide engineering services to design and implement erosion repairs, stream stabilization, and improvements to the hydraulic structures associated with Sunken Garden. In addition to repair of the stream channel, it is a primary goal of this project to preserve and improve the salamander habitat in the spring-fed pool and channel. Additionally, the project will address structural deficiencies and restore the historic stone masonry walls associated with Sunken Garden.
The project will include a partial realignment and expansion of the spring-fed stream channel to a new outfall on Barton Creek, as well as stabilization of a portion of the existing channel and modification to the inner-most stone wall to improve the outlet from the spring-fed pool. It also includes improvements to the recreational trail along Barton Creek, bank stabilization along Barton Creek, and the replacement of an existing pedestrian bridge with a new, longer prefabricated truss bridge to span the new outfall.
The final design contract will also include an evaluation of the historic stone masonry walls surrounding the Sunken Garden Spring and design for repair and restoration of the structures. Combining the erosion repair, habitat enhancement, and structural restoration elements into one contract for design and construction leverages the combined expertise of the Watershed Protection and Parks and Recreation Departments, and will result in reduced impacts to the public, cost savings, and delivery of the best possible project.
Objectives
The project has three primary objectives: 1. To establish a stable spring-fed stream channel that significantly reduces erosion risk for the spring, the pedestrian bridge, and park facilities (trails, parking, and historic structures). 2. Enhance and expand the salamander habitat as required by the habitat conservation plan specified in the City’s permit to operate Barton Springs Pool. 3. Preserve the adjacent historic structures and increase public interaction with them through interpretive signs and viewpoints. Overall, the project meets these goals by creating a stable spring-fed channel with a significantly expanded area for salamander habitat. The design phase will be accomplished through a partnership between the Parks & Recreation Department and the Watershed Protection Department and is being managed by the Capital Delivery Services Department.
Anticipated Schedule
- 2023: Preliminary phase (ongoing)
- 2024-2026: Design and permitting
- 2026-2027: Construction and anticipated project completion
Please note that, as in any construction project, schedules are projected as accurately as possible, but all dates are subject to change because of the nature of construction and the weather.
Community Engagement
The Parks and Recreation Department will provide online project updates to keep the public informed on the project schedule.
Funding and Resources
Project design is supported by funding from the Historic Preservation Fund and Watershed Erosion Control and Stormwater Funds.
Contact Information
For questions or more information, please contact Minda Sarmiento, P.E., Capital Delivery Project Manager by email or at 512-974-5645.