The Past: A History of Capes Dam


By Candice Brusuelas

Save the SMTX River


San Marcos City Council voted to remove Cape’s Dam in March of 2016, among concerns of recreation, safety and endangered species. No one talked about history. The topic wasn’t brought up. But the fact that the dam and the mill are over 150 years old, and eligible for the National Register of Historic Places, makes historical consideration of great importance.


An existing slough was the base of what is now the mill race. In 1867, the dam was built, sending of water farther down this channel to a bluff where the mill race and main channel converge once again. The water passes the mill wall on the bluff, and creates a waterfall into a clear, blue swimming hole where many San Marcans enjoy recreational activities.


Severe floods in 2013 and 2015 left the dam heavily damaged. In need of a repair that never came, the little dam remains crumbled, messy, and dangerous. The city and US Fish and Wildlife, instead, decided to remove it.


The Texas Historical Commission was notified of the proposed removal only after the demolition was already being planned, and a study was already funded on the removal. The late notification, and lack of public opportunity for involvement, were clear violations of the National Historic Preservation Act of 1966.


Since, the wheels of demolishing the dam slowed to a seeming crawl, the original funds US Fish and Wildlife set aside for the demolition is no longer available, and the San Marcos Historical Commission is set to review the issue on Sept. 6.


While history is not the only consideration for the dam’s repair or removal, its value should not be overlooked. It marks burgeoning industrialization in one of the longest continually-inhabited areas in the US. The mill is one of the oldest in Hays County, and the only one from that time period still intact.


Architectural Historian Lila Knight has studied San Marcos’ long history of dams and the purposes they served.


“I think it’s very beautiful,” Knight says of the remaining mill structure. “There’s a lot there we can tell about the post-civil war period onward. I think that’s what people sometimes forget. Structures, they change over time. Even houses, they get additions, and those can be very important in telling you how people’s lifestyles change.”


There used to be many more dams on the San Marcos River than there are now. Most became damaged and removed over time. Without the need of the mills, the dams weren’t really necessary either. Yet, even with only a part of the mill remaining, Knight argues, their historical value is worth preserving to piece together the evolution of the Central Texas area.


“If we only saved things that were whole, then we wouldn’t know anything about Native Americans,” she said. “Most of their things are partial.”


The concrete structure at the end of the mill race shows us how people adapted to a little later technology. Instead of the big mill wheel, there are metal turbines inside the concrete structure, allowing faster turning, and therefore, more efficient power. Coupled with other knowledge of the time period, like photos of later cotton gins, historians can piece together the development of early Central Texas.


Before the railroad came in 1880, settlers in San Marcos needed a way to cut lumber for their houses. Knight believes it was originally a sawmill for that purpose, and often, mills were used for multiple purposes, including cotton ginning and grist milling.


Because the main structure of the mill is gone, we don’t know for what this particular mill was purposed over the years. Mills were as essential to a community as a sewer and water system are to us today, Knight said. There used to be many mills on the river, even as many as a dozen in San Marcos.


Mill races made multiple mills possible. The diverted water would flow down the mill race, and its momentum would turn the mill wheel for power. Mill races allowed for gated water control to the mill, and allowed the river to flow at nearly the same pace for other mills downstream.


Capes Dam, itself, is a crib dam, constructed by a series of wooden frames filled with rock, stacked on one another. This allows the water to flow through the dam, but diverts enough to create a channel in the mill race.


This type of dam is less likely to break when hit by flooding, as opposed to concrete dams, which crack, Knight says. And if it does break, a crib dam is easier and cheaper to repair.


So why is the City of San Marcos disinterested in preserving their history? Knight says the city used to welcome newcomers with the enticing prospect of building a mill of their own, on the clear waters of the San Marcos River. As integral as the river is to our community, we, its residents, are little informed about its past, Knight argues.


“The city really ought to take advantage of (the mills) and do more to educate people about where the mills were,” she said. “It’s really kind of fascinating. That is the earliest industry in SM and they’re just oblivious.”


After all, a mill and adjoining dam is what created Spring Lake, on which the celebrated Aquarena Springs theme park was borne. Without it, the lake would have never existed.


The Spring Lake dam powered many businesses, including ice houses, a cotton gin, and a power house (for generating electricity). Parts of the lake and its history are preserved, like the hotel where guests used to stay.


The mill at Capes Dam will likely deteriorate without water in the mill race. Both sides of the repair/remove argument agree that there will be little to no water in the mill race without the dam. Without the water, the well-established banks of the mill race will erode over time – tree roots will become exposed, plants will die, mosquitos will breed in the moist, stagnant trench.


Aside from being an unattractive and unhealthy environment, those same banks of the mill race hold up the concrete mill wall. As the channel walls erode, the wall will destabilize, and, Knight predicts, will likely collapse into the pool below.


No viable solution or assessment has been made in association with removing the dam. Removing the dam itself would be cost-effective, but filling in the mill race causes yet another problem. The Woods, the large apartment complex along the mill race, has underground concrete reservoirs to release water runoff slowly into the mill race. But with the mill race filled in, the water would likely back up and flood. The dirt would likely loosen and erode with heavy rain as well.


No financial assessment has been made for restoring the dam either, which Knight believes would be most effective with someone who has experience with crib dams or historical restoration. She says fixing the dam, she expects, would be simple and cost effective if done correctly.


“No assessment has ever been made on restoration,” Knight said. “And I’d really like to see someone hired with knowledge of preservation and historic dams and engineering do that kind of assessment.”


Preservation Texas is a consulting party on the matter under the National Historic Preservation act, and acknowledge that Capes Dam is one of many historic dams that are endangered by the National Fish Passage Program, which seeks to protect fish migration by removing dams that block their way.


As they say on their website, “As dams age and as community relationships to Texas waterways change, the removal and replacement of historic dams is becoming an emerging preservation challenge.”


The Hays County Historical Commission and many locals have expressed their desire to restore the dam instead of remove it.



Read next Sunday: The Future: What Capes Dam restoration or removal could mean for the river