San Marcos Mercury | Local News from San Marcos and Hays County, Texas

COVER: River-goers relax on Thompson’s Islands overlooking Cape’s Dam in September 2012, prior to floods that damaged the historical structure. MERCURY FILE PHOTO by JAMIE MALDONADO. © 2012, All rights reserved.


The San Marcos City Council may be jumping the gun when it comes to their decision to remove the Cape’s Dam. Their decision, thus far, has been primarily based on a single report conducted by Watershed Systems Group.

The dam removal study stated that it would not affect recreational activities in the area. Further discussion with scientists and local residents who use the affected section of river for various recreational activities, say this is not the case and they have urged the SMCC to reconsider their recent decision to remove the dam.

The decision was brought to the the city council’s agenda in September 2015, following the recent floods, which affected many parts of Central Texas, including areas along the San Marcos River. In a study commissioned by the city, WSG concluded that the dam’s removal would “reestablish natural current velocities, remove fine sediment accumulation, and restore coarse sediment transport within this reach of the San Marcos River, thus providing improved habitat for vegetation growth and expansion.”

The report also stated, “There are zero positive benefits to the environment from Cape’s Dam.” These statements, along with a $35,000 grant, provided by The U.S. Fish & Wildlife Service (USFWS), has enticed the SMCC to move quickly in their efforts to remove the dam.

According to the grant, the city could be relieved of any out-of-pocket expenses specifically related to the dam removal only, but must agree to never rebuild the dam. U.S. Fish would like a 50/50 cost share but could be covered through in-kind services.

What the city has failed to recognize is that federal funds, such as this grant, cannot be applied to remove anything listed on the National Historical Register – something that applies to both Cape’s Dam and the left channel of the San Marcos River which forms the Thompsons Islands.

Historical significance

Cape’s Dam original purpose was to move additional water through a slough that became a Mill Race area to aid in the production efforts of a local saw mill and cotton gin. The Mill Race has an irrigation record which dates back to September 9th, 1895, filed by a well-known Veteran, Dr. William Alexander Thompson, and currently forms several islands called the Thompson Islands.

In 1994 the mill, along with the islands, awarded the honor of receiving a Texas Historical Marker, which is still present today. In 1985 it was officially listed on the National Register of Historic Places. The Thompson-Cape Dam and Ditch Engineering Structure was the site of the first important industrial activity in Hays County and listed under the identification 41HY164. The dam, artificial sluiceway, and mill-wheel foundation were built along the San Marcos River in 1865.

It comes as a surprise to many San Marcos residents that the SMCC would rather destroy these historical landmarks rather than restore and preserve such a significant part of our community’s local history. For more information on the historical significance surrounding the dam, visit or

Recreational significance

In addition to the historical and environmental concerns, removing Cape’s Dam will have a significant effect on the recreational activities in the area. Cape’s Dam and the Mill Race provide an outlet for many aquatic activities – including canoeing, kayaking, paddle boarding, fishing and swimming. Boy Scouts of America organizations from all over Texas, rehabilitation programs designed to aid in the recovery of disabled veterans, and various other youth groups that visit San Marcos use this area as a training area and refuge from the flow of the main river channel. The WSG report states a slight increase in recreational ability without the dam but does not include popular activities such as swimming, fishing or Yoga paddle boarding as a form of recreation. Just those four would be a significant loss if the dam is removed.

Ben Kvanli, a San Marcos resident, says removal of the dam will significantly lower water levels in that area of the river, thus threatening the ongoing success of his business and Veteran rehabilitation programs. Kvanli owns the Olympic Outdoor Center, a kayaking training school that provides therapy to veterans through kayaking. “For us that’s the main concern,” Kvanli said. “That’s where we train, so if you don’t have enough depth then you can’t do the exercises we teach to our customers.” Losing the Dam will choke off the left channel of the San Marcos River (Mill Race) which is heavily used for majority of youth groups, and people looking for a safe passage because if its slow moving water.

Environmental significance

Along with the documented and clear historical significance, there are also several environmental factors that will be affected by the removal of the dam. Over the last 150 years, nature has taken hold of this area and flourished, harboring some of our endangered species – including the endangered Fountain Darter and Texas Wild Rice. The Cape’s Dam Weir creates areas of slow and fast moving water which provide ideal habitats and environmental conditions for the species to reproduce and thrive. City council’s decision to remove and not repair Cape’s Dam Weir is based on a single scientific opinion.

The WSG study fails to address significant variables and only accounts for less than half of the measured discharges on the San Marcos River. The report also takes into consideration only three variables: flow, depth, and substrate. Rivers are far more dynamic than basing an entire study on only three variables.

It is apparent there are multiple sides to this story, which is why San Marcos residents are urging the SMCC to allow additional research, on both recreational and environmental impacts, and more discussion prior to finalizing the removal of the dam.

As the project stands there are still many unknown aspects and associated costs. What is the plan for the Mill Race, a ¼ mile stretch of river that is expected to go dry? What is the cost of approximately 20,000-32,000 sq. yards of fill if it were to be filled in? What is the cost and plan for areas such as the Thompson’s Island waterfall that are expected to become stagnant when the Mill Race stops flowing? Is it not in everyone’s best interest to consider all factors and scenarios surrounding the removal of the dam? Many hope SMCC will open the door for a more thoughtful and constructive discussion.

San Marcos

The San Marcos Mercury welcomes original letters to the editor about issues of public interest. Send letters through our contact page or email them to Editor & Publisher Brad Rollins.

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