Purgatory Creek basin: ‘It’s a lot of water’

City engineers are in the early stages of a project to increase the capacity of Purgatory Creek, and they want input from residents.

At a community meeting held Wednesday at the San Marcos Activity Center, project engineer John Espinoza laid out the project’s goals and constraints and asked attendees to share their thoughts.

“We’re trying to get your input, your ideas,” he said. “... We’re in the planning stages.”

The main purposes of the Purgatory Creek Improvements project, Espinoza said, are flood mitigation, sustainability, making the creek more of a community asset and staying within a reasonable budget.

Currently, plans for the project include excavating the creek channel to deepen it and allow it to hold more water, adding sidewalks and trails, modifying bridges and culverts, and planting riparian zones along the creek to allow vegetation to filter the water and slow its flow. 

The project will have to take into account the goals and principles set forth in city plans, he said, like the city’s comprehensive plan, stormwater master plan, transportation and greenways plans and parks master plan. 

Moreover, Espinoza said, the project will have to take into consideration the hiking trails and natural area along Upper Purgatory Creek, the outflow from the creek into the San Marcos River near Children’s Park, road and railroad crossings, and the overflow between Purgatory Creek and Willow Springs Creek. There are also environmental, permitting and other factors to consider, including the presence of wildlife and the potential discovery of artifacts during the project work — and then there is the vast amount of water to consider. Espinoza presented a map showing the size of the Purgatory Creek Watershed, which stretches along Ranch Road 12 past the Wimberley Junction and up to the intersection of Purgatory Road and Ranch to Market Road 32. 

“It’s a large watershed,” he said. “We’re dealing with a lot of water.”

Espinoza also pointed out other capital improvement projects that are either in the planning stage or under way: drainage projects for Bishop, Faris and Travis streets, along with improvements at Dunbar Park, can all affect the Purgatory Creek project. For instance, the Travis Street drainage project is set to include an outfall into Purgatory Creek and a bioretention pond to improve water quality. Maintenance and right-of-way acquisition are two other factors in the project.

“We’ve got to absorb all of that,” Espinoza said. 

Currently, he said, the project is in its first phase, which involves data collection, analyses and estimating costs, but the city is already seeking public input.

“What are your ideas?” Espinoza asked the audience Wednesday night. “What are your concerns about this project?”

Audience members brought up several factors, including 2D modeling of water flows, sediment entering the San Marcos River when the flow from Purgatory Creek increases, keeping debris out of the creek bed, the roles that vegetation can play in improving water quality and slowing the current, and collaboration with other governmental bodies in flood mitigation.

“I think the meeting went well last night,” Espinoza said in an email Thursday. “We were able to accomplish our goal of receiving comments from the citizens.”

Another public meeting about the project will be held in November or December, Espinoza said. In the meantime, he added, any residents with further input or concerns about the project can email jespinoza@sanmarcostx.gov or EngInfo@sanmarcostx.gov.