(Bloomberg) -- A billionaire seeking to build a resort with luxury homes in the Texas Hill Country is facing off against neighbors opposed to development on environmental grounds, highlighting the growing tensions as the region’s economic surge fuels a boom outside Austin.

Steve Winn, who made his fortune as the founder of a property-management platform called RealPage Inc., says the 1,400 acres he’s dubbed Mirasol Springs will be a model for conscientious development. Sewage will be processed on site to be used in irrigation, and all the buildings will have cisterns to catch rainwater. No fertilizers or pesticides will be allowed, and more than two-thirds of the land will be put into a conservation easement.

It isn’t enough for the environmental groups seeking to preserve the area’s rugged landscape of rolling hills and clear-water streams in the face of encroaching development, automobile traffic and tourism. The opponents of Mirasol Springs have gone as far as lobbying the federal government to declare a local species of salamander as endangered in the hopes it will throw a wrench into efforts to build on the site, near where Roy Creek flows into the Pedernales River about 35 miles west of downtown Austin.

“If we preserve the spring flows and the river to save the listed threatened creatures, we are saving ourselves in the process,” said Bill Bunch, the executive director of the Save Our Springs Alliance, a nonprofit focused on water resources. “If we are going to pump our rivers or springs dry and extinguish these species, then we are going to follow soon thereafter.”

The Hill Country sprawls across all or part of more than 20 counties in central Texas, with booming Austin and San Antonio on the region's eastern fringe driving a transformation from ranchland to suburbia. As technology companies like Oracle Corp., Tesla Inc. and Samsung Electronics Co. invested billions in the area, urban real estate prices surged along with the population, prompting some homebuyers to look further afield for cheaper properties.

It’s easy to see why the area around Mirasol Springs, which is in unincorporated parts of both Travis and Hays counties, holds particular appeal. Several wineries and wedding venues are within a few miles of the site, which is just down the road from Pedernales Falls State Park and an environmental conservation sanctuary called Westcave. Visitors seeking to take a dip with the enormous, semi-docile catfish that inhabit the nearby Hamilton Pool Preserve, a county-owned swimming hole, now need to make summer reservations months in advance. 

Surrounding all the natural beauty are several luxury subdivisions built in recent years that offer amenities like walking trails, lazy river pools and pickleball courts. At the Belvedere — a gated community with 223 residential lots — single-family homes sell for more than $2 million. A 53-acre estate nearby with a three-bedroom, 3,283-square-foot house is listed for $5.7 million.

Representatives for Winn, who is based in Dallas, are mum about the project’s total cost, the average size of the homes that will be built and the prices it plans to charge. When it’s complete, the development is set to have 40 residential homes, along with a 71-room hotel, 30 resort residences and an event barn. A restaurant will incorporate ingredients grown on site, a nod to New York’s well regarded farm-to-table restaurant Blue Hill at Stone Barns.

With projects of similar scale going up throughout the Hill Country, conservationists are ringing alarm bells. 

“This iconic landscape, filled with natural beauty and heritage-rich rural communities, is facing tremendous threats from sprawling growth and development,” the Texas Hill Country Conservation Network said in a 2022 report. “The window of opportunity to keep the Hill Country rural, natural, and vibrant will likely close within our generation.”

The strongest opposition to Mirasol Springs has come from Lew Adams, a 77-year-old retiree and former film producer, who along with other relatives and another family, the Blacks, owns a 50-acre parcel surrounded on three sizes by Mirasol Springs. The Adams-Black lands, called Roy Creek Canyon, consists of two primitive cabins, outhouses and a steep canyon cut through layers of limestone. It’s an indisputably beautiful oasis with its own cooler microclimate and several pristine swimming holes.

Adams is particularly concerned that unchecked water use at Mirasol Springs will dry up the springs that feed Roy Creek and keep his canyon so lush, despite the developer’s assurances that it will only pump groundwater when surface water from the Pedernales River is unavailable due to low levels. Parts of the Hill Country are currently in “exceptional drought” conditions, the most severe level.

Adams has hosted scientific research groups, University of Texas biology classes and officials from the Texas Parks & Wildlife Department at his property to showcase its biodiversity. It's currently acting as a field lab for students at St. Edwards University in Austin. The canyon is home to the endangered golden-cheeked warbler, and the newly discovered type of salamander, which the Save Our Springs Alliance has petitioned to get on the endangered species list. The amphibians live around limestone springs and other water-filled underground spaces in the region, and their advocates say preserving habitats like Roy Creek Canyon is critical for their survival.

Adams’ father, Red, bought the canyon with a friend in 1941, and the land has mostly been used for research and family getaways in the years since. Adams said he invited Winn down to the canyon after his real-estate development firm, Mirasol Capital, bought the surrounding land in 2018, and said his visitor was blown away by what he saw.

“It was in the springtime, it was gorgeous,” Adams said. “We walked down and Steve was standing there, and he was looking around at the trees and everything and he turned around and said, ‘I feel like I’m in a cathedral.’”

Adams now feels betrayed by Winn’s plans to develop the land. “You say this is a cathedral to you, and yet you are willing to do something that could totally desecrate it,” he lamented.

Winn, who sold RealPage for $10.2 billion in 2021,  confirmed he took a tour of the canyon with Adams and declined an interview request.

“Mirasol Springs will create an experience that is paired with education, conservation and environmentalism,” Winn said in an emailed statement. “When all of these visions are aligned to work together in harmony, it presents a model for future development.”

On its website, Mirasol Springs labels itself as a “conservation-scale development” designed to serve as a model on how to embrace and preserve the natural landscape of the Texas Hill Country. There are plans to build a field station to be used by University of Texas classes studying birds, native plants, insects and aquatic biology. 

With the commitments to limit water use and runoff, the conservation easements and an effort to restore native vegetation such as bald cypress trees, the developer says it can be a strong steward of the land.

For now, the development site sits mostly empty as Winn waits on groundwater permits and the submittal of a site development permit in Travis County. Driving by, motorists will see a dog kennel, a chicken coop and an old farmhouse used by a previous owner. The developers are hoping to complete Mirasol Springs in the first quarter of 2026.

“It may be that the development on its own has minimal impact out there,” said Robert Mace, executive director at the Meadows Center for Water and the Environment and a professor at Texas State University. “But once the area starts getting developed, it’s all going to compound and cause more problems.”


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