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

In a rebuttal to commentary we published last week, University of Texas biology professor MOLLY CUMMINGS writes that the San Marcos City Council should “take advantage of the wealth of local scientists that have different perspectives on the biology of the San Marcos River.” 

September 22nd, 2015
Letter: No one is ‘omniscient’ about best option for Cape’s Dam


I have never found public mudslinging to be a productive form of community service, so I will refrain from retaliating in kind to Dr. Hardy’s ad hominem attacks on your editorial page last week. However, his letter does raise a big question: Who should San Marcos city leaders consult for expert advice about the fate of the weir at Cape’s Dam?

When communities turn to scientists for advice about natural resources, we need to keep in mind that no single scientist is omniscient. We all study a few things in great detail, but few of us have intricate knowledge on the complete picture. It is important to call on diverse experts with different perspectives to inform public leaders. Dr. Hardy and I have acquired different knowledge sets regarding biodiversity elements in Texas rivers, and we can both serve the communities’ interest by sharing them with the San Marcos City Council.

While Dr. Hardy’s claim that my science is sloppy is contradicted by my extensive publication record in prestigious scientific journals, it is true that I am the proud Captain of the US Women’s Kayak Polo Team. I felt no need to mention this in an editorial regarding the biology of Cape’s Dam’s fate, because the outcome of the city’s decision on this matter will have no bearing on my kayak polo play. Contrary to Dr. Hardy’s offensive claim, it is my professional concern for native fish species that motivates my interest in Cape’s Dam — not my recreational pursuits.

I study the behavior of poeciliid fish — a diverse group of small fish with well over 180 species, and I have observed and collected these fish in their native habitats from Mexico, Trinidad, Costa Rica and various Texas waterways for over 15 years. In that process, I have acquired knowledge about the particular habitats in which these species thrive, and have recently become distressed by the declining populations of rare and native mosquitofish species (Gambusia sp.) in Texas. Ensuring habitat-friendly environments for all fish (the big and the small) is important and variable flow regimes with bank vegetation are vital for many poeciliid species.

It makes complete sense to me that the San Marcos City Council contracted with Dr. Hardy, an environmental flows specialist with extensive knowledge of the San Marcos River ecology, to project potential repercussions of weir removal at Cape’s Dam. But I hope that the city council will seek additional advice from other scientists with different perspectives. The insight I have to offer is restricted to one slice of the biodiversity pie — the habitat preferences of poeciliid fishes.

Additional useful input might be given by U.S. Fish and Wildlife scientists in San Marcos such as Mara Alexander and Catherine Phillips who have published on the different habitat needs of juvenile and adult native Fountain darters. More global perspective on Texas fish can be provided by Dean Hendrickson and Adam Cohen, curators of the Fishes of Texas online database.

The San Marcos City Council is commendably listening to a number of different citizen advocate groups about the fate of the weir, but I hope they also take advantage of the wealth of local scientists that have different perspectives on the biology of the San Marcos River.


MOLLY CUMMINGS is a biology associate professor in the University of Texas’ College of Natural Sciences. 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.

An old mill race runs from Cape’s Dam alongside the eastern edge of Thompson’s Islands before rejoining the river. MERCURY FILE PHOTO by JAMIE MALDONADO. © 2012, All rights reserved.

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14 thoughts on “Letter: No one is ‘omniscient’ about best option for Cape’s Dam

  1. Dr. Cummings, with all due respect, there has been no mud slinging nor any ad hominem attack. You chose to publish a public opinion letter on the status and ecology of the San Marcos River as it specifically related to environmental benefits of rebuilding Cape’s Dam (weir). I simply pointed out to the public that you were factually in error. Your rebuttal commentary does not dispute any of the science based facts I brought to the public’s attention. I would gladly have you, or any of the scientists you pointed out, to come and inform City Council on their perspectives of the San Marcos River as it relates to the Cape’s Dam issue and the implications to the ecology of the system. I have spent 30 years working on imperiled taxa throughout the world and as I noted 15+ years on the San Marcos River. If I thought rebuilding Cape’s Dam was in the best interests of the native taxa in the San Marcos River, I would definitely say so.

  2. Dr. Cummings, just to set the record right, there is NOTHING in my opinion letter denigrating your stellar academic research record nor can anyone who reads it find the words “professors sloppy work”. The use of those words in the byline was chosen by editor Brad Rollins. I had nothing to do with his choice of words when he published my letter.

  3. For the record, I wrote the headline for Dr. Hardy’s guest commentary, as I did for both of Dr. Cumming’s letters to the editor. I thought the use of the word ‘sloppy’ was a fair characterization of the arguments he advances in his piece, but it is not his word choice.

  4. Let’s do a petition and let the citizens decide on the fate of Cape’s Dam. Oh wait, we already tried that with another controversial topic and got sued. And, the City Council is proposing more stringent requirements for future citizen petitions. What happened to government for the people, by the people…….

  5. Hey river rat… FYI, most of the citizens don’t care what happens to Cape’s Dam. We gave up long ago on San Marcos.. Now we just exist and our mantra is “qué será será.”

  6. Jim, so you did a poll of the citizens? Think not. Most recreation boaters that I know don’t want to see it go away. The millrace will go dry and we will no longer have a boat put-in spot at Thompson’s Island that is used by the Boy Scouts, church groups, and many other groups. I have been using this spot to launch boats for over 20 years.

  7. riverrat, well then if you have been using that spot for 20 years, you definitely have my vote. I mean, that’s definitely what I would base my rationale for saving the millrace on – whether or not someone has a particular convenient space to launch their boats that they have used overtime. Because I’m sure there are no other convenience about to launch boats on the San Marcos Marcos River. Not!

    You see, that’s my fear, that if you were just to let the citizenry decide without any input from scientists like Dr. Hardy, that are concerned with the biology of the river and the long-term health of the river long after you’ll be dead and not able to put your boat in the river in a particularly convenient spot, then that will be the type of rationale people base their decisions on. Smh

  8. Was the aquatic life there before the dams?

    My degrees don’t include ones appropriate to answer the question.

  9. Winchester, yes! The aquatic biology of the river above and below Cape’s Dam is classified as exceptional by the State. But, CommonSense seems to think that I know nothing about biology and only have recreational interests. Wrong!

  10. Now wait just a minute riverrat. You’re saying there was aquatic life there before the dam was built and you have credentials to support that statement so tell us; why won’t there be life after the dam is removed?

  11. riverrat…nope, no poll but I’m telling you we long-time citizens just don’t care anymore what happens in/to San Marcos or to Cape’s Dam. It’s all about what the University wants. You can’t fight them or City Hall so get used to it as we have.

  12. If the millrace goes dry San Marcos will lose a perfect place for adults to teach children to fish and the only place with safe wheelchair access for fishing.

  13. So, let me get this straight. All the aquatic life was there before the Cape’s Camp dam and the icehouse dam were built.

    Why can’t they survive, and maybe flourish, once their original natural habitat is restored?

  14. Please help save our Mill Race and water fall. Why cant both parties have something to share? Lets help protect and fix the dam to be safe. I dont see how you could canoe the river when CFS is around 120-150. This should have way more discussion.

    Email me if you are interested in wanting to put a stop or delay so we can have a real discussion or have the citizens vote on it. The city seems to rather spend over $1,000,000 to put two way roads downtown that people have voiced that they do not want. Today I was stuck on LBJ infront of a great new restaurant called Crafthouse. They were getting their food delivery. I had to move over to the only other lane which was fine. If it had been two way what would we do? Make the food and beer trucks park 5 blocks away to deliver to all the businesses? They have suffered enough from the last construction. Isn’t it ease to look one direction for on coming traffic than both ways? We have more foot traffic than ever before downtown! Way to go Sam with Main Street on a job well done!

    Anyways if you are interested in saving the dam and water height between Capes and Rio Vista please email me.


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