Less than a mile east of I-35 in San Marcos, a dam on the San Marcos River has become the focal point of a debate over the future of the river itself.

Cape’s Dam is 150 years old, and water easily passes over the structure, which has been damaged in recent years by consistent flooding. Jagged pieces of metal and concrete jut out of the water, a foreboding terminus on that end of the river. A man-made channel, known as the mill race, allows kayakers and tubers to bypass the dam and reconnect with the river’s main channel farther east near Martindale.

City Council voted March 16 to begin the removal of the dam, but dam advocates did not take the vote as a sign of defeat.

“I believe we’re going on an ecological gamble when it’s presented as the truth or a fact that [the health of the river] would improve [if the dam is removed],” said Brian Olson, one of the opponents of dam removal. “It could get better. It could get worse. We know what Cape’s Dam has right now. We know what we have.”

The two sides of the issue are united in their apparent concern for the health of the river and the viability of endangered species, including the fountain darter and Texas wild rice, a fish and plant, respectively, only found in and around the San Marcos River.

Those two organisms were partly responsible for the creation of the Edwards Aquifer Authority. In the early ’90s a court ordered the creation of the authority to regulate withdrawal of water in part to protect the endangered wildlife that call the river home.

The pro- and anti-dam parties are polarized as to how the dam’s removal would affect both species.

“People can never understand how important it is that we take care of the wild rice,” said Dianne Wassenich, director of the San Marcos River Foundation, which has voiced support for dam removal. “Without these endangered species in our river we will not have a river. That’s all there is to it.”

Advocating for the dam

Olson and those advocating against removal of the dam have voiced concerns that removal will lower water levels, reduce safety for kayakers and canoers and threaten wildlife habitat and recreation—including kayaking, canoeing, paddleboarding and tubing.

Thom Hardy, the chief science officer at the Meadows Center For Water and the Environment at Texas State University, has led the studies indicating dam removal would provide a net benefit to the river and the wildlife that call it home.

Olson has questioned Hardy’s motives, arguing that dam removal would provide “golden opportunities” to an aquatic researcher such as Hardy. Hardy’s private company, Watershed Systems Group, has been paid $23,870 by the city of San Marcos for work on the river in 2012 and 2015, according to a public information request.

Aside from direct financial gain, Olson said dam removal would create research opportunities that could lead to lucrative speaking engagements for Hardy.

Hardy, on the other hand, has argued that as the chief science officer for the Meadows Institute and an endowed professor of environmental flows at Texas State, his job is to study the dam whether it stays or is removed.

His most recent study, completed in 2015, indicates removal would improve habitat for fountain darter and Texas wild rice under most drought and non-drought conditions. 

But Olson takes issue with the most recent studies indication that dam removal would improve habitat for fountain darter because a previous study indicated the dam’s removal would actually provide a less suitable habitat for the fish.

Hardy said the study that Olson references was conducted before Hardy fully understood the effects the dam’s removal would have on plants and wildlife in the river.

In favor of removal

Proponents of the dam’s removal have said that the dam should be removed to restore the river to its natural state.

“We’re altering the river with a dam,” Wassenich said. “That’s why you shouldn’t just rebuild them. You should—when you can, when they no longer have a function—you should get rid of them.”

Structures such as Cape’s Dam, which is known as a low-head dam, can be dangerous for those using the river. In 1997, San Marcos Police Chief Larry Kendrick died in the San Marcos River  when his craft hit a similar dam that was later removed in Ottine while training for the Texas Water Safari. 

Hardy’s studies indicate dam removal would cause at least 6,762 cubic meters of sediment to be removed from the bottom of the river. So although the water level may drop, that decrease would be accompanied by a corresponding lowering of the river’s floor, meaning depths would remain relatively consistent with current conditions, he said.

Wassenich said the science backs up removal of the dam.

“The river foundation has a reputation we would not endanger by flippantly endorsing something that could harm the river,” Wassenich said.

The city’s perspective

City Manager Jared Miller said the city’s parks department is working to develop a plan for parkland adjacent to the dam. Whether the dam is removed or repaired—and the city is moving forward with removal of the dam—a park will not be opened until the safety hazard presented by Cape’s Dam is addressed.

Miller said removal could occur by mid-2017.

The city envisions the new park near Cape’s Dam as a “very passive” park, he said. The site might feature open green space, picnic tables and trash cans, he said, but it will likely not include tennis or basketball courts or a pool, such as those found near Rio Vista Park, less than a mile upstream of Cape’s Dam. The parks board and City Council will have opportunities to provide direction as to what the park should include, but Miller said he does not foresee a long public input process.

Additionally, Miller said the city is working to find options that would allow the mill race to continue having water in it even after the dam is removed. Cost estimates are unknown at this time, he said.

The removal will need the approval of U.S. Fish and Wildlife Service, Texas Parks & Wildlife and a slew of other agencies, Miller said.

“I can’t imagine a more transparent and grind of a process,” Miller said. “This has been a very time-consuming process. It’s not like it was something that was slid under the rug or happened quickly. This was a very, very slow and deliberate process.”