At a spot just east of Interstate 35, amid elephant ears and tall grasses, the whitish-blue San Marcos River widens out, eddying around and over a low-slung dam, the burble of water washing out noise from the highway only a few hundred yards away.
The fate of the dam, which is falling apart in places, is now the center of a dispute pitting a venerable local environmental group against an Olympic kayaker.
Central to the future of the dam, which the San Marcos City Council will take up Tuesday night, are questions about whether waterways ought to be restored to their pristine condition, or whether historical, man-made changes ought to be embraced.
At stake, perhaps, is the fate of endangered species and a burgeoning recreation-based economy.
Athlete and kayaker Ben Kvanli, who lives and runs a kayaking school on the river just yards upstream from Cape’s Dam, says that even when the river was truly “wild” its flow was impeded by natural dams of rock formations. The dam, which was originally built a century ago or more, as part of an effort to mill cypress trees, has protected the river from yet more pollution, says Kvanli, who competed for Guatemala, where he was raised as the child of missionaries, in the 1996 Olympics.
But the San Marcos River Foundation wants the dam gone.
The group, a 30-year-old nonprofit dedicated to protecting the river’s flow and the rare species found in it — including Texas wild rice and the fountain darter, a small, reddish-brown fish — says the dam makes it difficult for fish to spawn and jeopardizes habitat.
The river is “fine for recreation, and it’s better for the river and habitat if we remove the dam,” said nonprofit director Dianne Wassenich.
At times, especially on Facebook, the dispute has grown vitriolic, with each side accusing the other of lying or papering over facts.
Everyone appears agreed something must be done about the dam, which rises about 7 feet from the deepest point of the river bed and is roughly 100 feet across. Currently, it features bits of exposed rebar and cracked concrete — detritus from previous repair jobs.
The city, which took possession recently of the dam and surrounding property, some of which is slated for a park, included $1 million in its budget over the next couple of years for analysis of the problem and repairs.
Kvanli, who counts support from some outdoor enthusiasts and national kayaking organizations, says Cape’s Dam could be a second Rio Vista Falls Dam, another dam upriver on the San Marcos that has drawn kayaking enthusiasts from around the world. The artificial rapids, with at least three drops totaling about 8 feet, are the central attraction of a whitewater park, which also draws tubers.
But Thom Hardy, chief science officer at the Meadows Center for Water and the Environment at Texas State, says the city should remove the dam.
He will the present the findings of his city-commissioned study on Tuesday, but the San Marcos City Council is not slated to take immediate action.
The dam inhibits flow along the river that the wild rice requires to thrive, he said.
“There are plenty of other opportunities down here for recreation,” said Hardy, who said that even in the absence of endangered species he’d want the dam removed: “I’d still want the natural condition of the river to be restored.”
On Monday, San Marcos City Council members took guided tours of the dam.
Kvanli and his supporters wore shirts that read “Save Thompson’s Island”: the dam helps maintain a fork in the river to channel some water into the old millrace, and the land between the stream and the river is known as Thompson’s Island.
By Hardy’s calculations, the millrace lies 4.3 feet above the bed of the river: If the dam is removed completely, there will be no water in the millrace at least 95 percent of the time, he said; if it’s shaved down to half-height, the millrace will be dry about half the time.
The fact-finding tour was the first opportunity for city officials to get a sense of the problem, said City Manager Jared Miller.
Mayor Daniel Guerrero said on Monday that he has not decided what should happen to the dam.
In the end, the final fate of the dam could be years away, said Wassenich, with a possibility of appeal to state agencies.