The San Marcos River Foundation lists answers below to incorrect statements written by dam advocates hoping to rebuild Cape dam. Our answers are offered in an effort to correct the incorrect information being circulated. We believe that it is time for all to unite in doing what is best for the river. We would hope the community could now focus on removing the dam and opening the park again as soon as possible.
- The historic eligibility of the dam and mill race, etc. will not be destroyed by removing the dam. There are ways to preserve the mill race as the Texas Historical Commission requests, which the city is investigating. We understand from USFWS (U.S. Fish & Wildlife Service) that the need to keep water in the mill race at all times is not always necessary in preserving historic dam-associated systems. The structure at the end of the mill race in Stokes Park can also be preserved. The shape of the mill race and the island, and Stokes Park have all been extensively altered over the last fifty years, and some of these alterations like the tall rock gabion, concrete sidewalks and steel bars are relatively new. Fill dirt, rock and rubble have been placed all over the park and island. The mill race is a shortcut channel dug across a bend in the river and has enlarged over the years from floods. It will continue to enlarge with future floods. That is the reality of hydrology and rivers. The dam will continue to be dismantled by floods. That is what happens to dams, and so it will be a recurring public safety problem for the city if left in place.
- It is not correct to say the city voted to demolish without knowing the historical significance or considering costs to repair the dam. The city actually voted to allow USFWS to begin the permit process that would be needed to accomplish dam removal, including many different permits. The city knew that there would be archeological and historical review requirements (as there have been for many projects in city parks along the river) and those reviews might alter plans. Applications had to be made by USFWS for sand and gravel permits, U.S. Army Corps permits, and endangered species permits as well. The city knew that alternatives would be looked at, so it was clear that cost comparisons would be made. The city, however, cannot just look at a one-time cost of fixing the dam— they have to consider the future maintenance of the dam after every flood. It is incorrect to claim that the money set aside by the City was specifically targeted for building a new dam, and this is verifiable with City Council meeting records.
- Regarding the claim that only one study was used, done by Dr. Hardy for the city: Dam advocates are focused on that study’s report without fully understanding that this specific study modeled the expected changes in the river channel that would occur if the dam were rebuilt at full height, half height and also if dam removal occurred. None of the previous modeling reports by Dr. Hardy evaluating removal of Cape’s Dam had included sediment transport and channel changes. This was explained often to the dam advocates, on many occasions. During the two years of discussion in Parks Board meetings and hearings, there was long discussion about the thick layers (10 ft deep in places) of sediment upstream of the dam that would move downstream if the dam were gone. The city wanted to know how the shape of the river would change (or not) as sediment moved downstream with river flows carrying it, under all three scenarios. This dam removal would cause less water to be backed up, but then the counter-effect of a deepening channel, as sediment moved downstream, also needed to be taken into account. So the city had Dr. Hardy do this modeling as a final step before they decided to begin the permit process—to be sure the river would remain deep enough. At Dr. Hardy’s request, the study included an assessment of a water contact recreation corridor that had not been considered in previous Cape’s Dam studies.
- However there are countless studies completed over the past decadesthat led USFWS to the conclusion that the dam needs to go. USFWS knows removal will improve habitat and return all flow to the river itself—instead of diverting water to a nonfunctional former industrial site that no longer has a use for the water. These decades of studies were conducted by USFWS, Texas Parks and Wildlife Department (TPWD), Edwards Aquifer Authority (EAA), and several universities, including Texas State University. These studies covered a spectrum of physical (channel changes due to dredging), chemical (water quality), and monitoring of the aquatic community including the endangered species. Those of us who watched the series of problems with the dam in just the past 30 years, while it was privately owned, also understand that the dam creates a longstanding public safety problem. Added to this is the knowledge gradually being gained from the change in the river below Rio Vista, resulting in loss of native aquatic vegetation and fountain darter habitat, and creation of a shallow gravel bar downstream of the Cheatham Street bridge. The dam advocate’s recent article listed studies starting in 2012, but that is actually a very brief list of only 4 years of studies, considering all the knowledge gained in decades of endangered species and fish studies that have been done on the San Marcos River.
- Regarding “substantially” more citizens asking to keep the dam, their signatures and letters were obtained by circulating incorrect info to the public about “the ways the endangered species would be harmed” by a group calling to “Save the River”. The group wants to keep diverting water from the river, and that is the antithesis of saving the river. During droughts it will actually be harmful to the river and to endangered species to divert water away from the river. Climate change means that droughts will be even more extreme, and we must be ready for that eventuality. We cannot allow the river to get so low that endangered species are harmed or destroyed. Those species are the only reason we even have a flowing river, since their need for adequate springflow caused the pumping limits on the aquifer to be enacted to keep San Marcos and Comal springs flowing. If they ever die off, the river will no longer be a flowing river except in very wet periods, because the aquifer pumping limits may not be enforced if there are not endangered species left in the springs and river.
- The claims by the dam advocates that Dr. Hardy changed his study to make the results look like there was more habitat later in the study—this was explained in detail to dam advocates by Dr. Hardy at a meeting months ago at the Chamber, but we repeat it here. Dr. Hardy was making sure all the information in the study was clear, accurate, and included aquatic vegetation. Preliminary study results were presented to the Parks Board, and based on questions received as well as listening to statements that were incorrect during City Council public comment periods, Dr. Hardy added material to the report to clarify these misunderstood issues. He also refined the habitat modeling to incorporate expected changes in aquatic vegetation. These changes in aquatic vegetation (including Texas wild-rice) which are the basis for fountain darter habitat, reflect the work of the EAHCP aquatic ecosystem modeling team where Dr. Hardy is in fact the Co-Principal Investigator. (EAHCP is the Edwards Aquifer Habitat Conservation Plan, a regional effort that plans to protect the endangered species by providing enough flow from the springs to keep the river adequately deep for those species even during a drought like that of the 1950’s. The EAHCP also works to improve aquatic habitat in the river for the species.)
- Hardy used the lower flow numbers in the study for Texas wild-rice and fountain darters because those are the flows when their ability to survive is more critical, not when flows are above the median, like this year. The dam advocates may be confused about the science of the life history needs of these endangered species. Attempts to disparage Dr. Hardy and his work is profoundly misguided. Dam advocates tried to intervene months ago to get the city to think there is a problem with Dr. Hardy’s credentials, and this was thoroughly debunked by professionals who know of Dr. Hardy’s international and stellar professional reputation.
- Moving on to the next science-related complaint about the sediment removal model using 300 cfs. That flow is equaled or exceeded about 10 percent of the time and is the appropriate flow to evaluate channel changes due to sediment movement. That type of flow is related to the effective discharge, which is the flow at which most sediment transport occurs. Dr. Hardy was doing his best to give the Council a realistic evaluation of the potential channel changes under full height, half height and full removal of the dam. The dam advocates’ contention that higher flows should have been modeled is perhaps based on their lack of understanding of how sediment transport and hydraulic modeling studies are conducted. (It is important to be sure that habitat suitability models in #6 above, and sediment transport models in #7 are not confused.) In addition, literally thousands of measurements from the river were taken to populate the model with real data about the channel shape and sediments. The amount of time and expertise that goes into such sediment transport and channel change models is astounding
- USFWS and TPWD agree that the mill race is not ideal habitat, and during drought, can rob the river of critically necessary water. USFWS and TPWD scientists, and Dr. Ben Schwartz of the Edwards Aquifer Research and Data Center, plus Dr. Hardy all agree that the best thing for the river and its fish and species is to remove the old dam. Dam advocates, on their own, without the benefit of any scientific study, have decided that fountain darters are going to be hurt by the dam removal. This incorrect info being spread by the dam advocates is not going to save the darters or any other endangered species. The incorrect information campaign is targeting people who do not understand the scientific studies and models done for decades on the San Marcos River.
- Then, look at the claim that the National Academy of Science review of the EAHCP suitability model expressed concerns about Dr. Hardy’s work. The NAS does not have “issues” with the modeling. They are pleased with the EAHCP, and the report excerpt quoted was related to the EAHCP model done for aquifer decisions. That report is not related to the dam, and again, an excerpt was used from a study without understanding it. The Texas Instream Flow program, which was reviewed by the NAS, relies on habitat suitability modeling as an accepted approach and basically every Bay and Basin Expert Science Team study to date, done across Texas in all major rivers, has utilized habitat suitability modeling.
The skilled and reputable scientists who have spent their lives studying endangered species in this river specifically, believe that keeping the dam is NOT good for the aquatic ecology and specifically NOT good for the health of the endangered species. The dam is also jagged, crumbling and unsafe. So let’s all put this “harming endangered species” argument to bed, once and for all. Let’s now try to have a sensible discussion about ways to preserve a historical site, get flood damage on the parkland fixed, get proper access built for fishing, boating and disabled people of all ages, and get that park open for San Marcans who love it and miss it.
The staff and board of the San Marcos River Foundation and Dr. Glenn Longley, one of the original three incorporating board members of SMRF in 1985, and Professor Emeritus of Biology at Texas State University
In response to further claims and misinformation presented on social media and local papers, SMRF has consulted with the proper entities involved to correct and clarify issues raised.
We have noted on Facebook countless videos of youngsters being urged to launch themselves over the mill race structure that the SMTX River facebook page claims is a waterfall on the mill race. (Note this is not the dam.) This concrete structure has caused the recent death of at least one person, and so we are concerned that this is a very dangerous practice, especially since the structure is posted with signs to stop jumping from that high point, posted after that young person’s death.
- We at SMRF support removing the dangerous jagged rubble and steel bits left of the dam, which would restore the full flow of the river to the river channel. (We know two kayakers who were bruised and injured recentlywhen they went over the dam rubble, not realizing it was there.) There have been claims that the bridge just downstream is too low, and thus dangerous to run into. Yet we see people on the river there floating under the bridge with no problem. The river is obviously not too high and swift to paddle, in that area, even with very little of the dam left in the river at this point. The springflows are still above average since we have had rains recently.
- There have been more claimsthat the water backed up behind the dam by IH 35, at the kayak business, is the only place that veterans can get in and out for kayaking if they have lost limbs. But yet there are frequent sightings of these kayakers using City Park, Sewall Park, Saltgrass area, Rio Vista and other sites in the city parks. And the river in town is a series of slow water pools from dams, so there are many spots without currents. And oddly, it is clear that there is not appropriate handicapped access to the river at the kayak business at IH 35, so cars are driving down on those riverbanks, and have worn the grass to bare dirt.
- What we really need is a park master plan for Stokes Park that is developed with grants and city funds so that our parks have good handicapped accessible entry points and fishing pier as well as a signalized safe portage routeacross the street. Everyone needs to realize that with the dam gone there would not be a need for a portage across that very busy street, unless there were unusual circumstances. Having the dam remain, of course, means that large groups of paddlers would have to continue to cross that street carrying canoes and dodging traffic, a serious safety problem right now (with no signals) especially for children.
- Regardinghistorical respect for the area, we agree that a focus on both Rio Vista and Thompson’s Island’s former uses for power for early industry, with explanatory signs about the history, would be great. Keep in mind that floods will make short work of signs; they will need constant replacement, and thus careful design and placement. We did not notice any effort by the SMTX River folks to pay any historical respect to Rio Vista Dam when they wanted it rebuilt into the Falls. Regarding any promises that anyone may have made to keep the Stokes Park exactly as it was under previous ownership, it must first be understood that the dam itself was not owned by the Stokes family.The dam was previously owned by the Thornton family who recently sold it to the developers of the Woods Apartments, who gave to the city. It has been in poor repair for a long time before the city owned it, and the very serious 2015 floods removed even more of it.
In an effort to understand the mill race better, some field surveys have been done recently covering Texas wild rice and other vegetation, and fish of all kinds. Here are results:
- Regarding the mill race at Thompson’s Island, it has been proved with dye teststo have extensive leaks. Since the river is always trying to enlarge it during floods, it forms enormous holes and a network of underground channels that run water from the mill race back to the main channel of the river. This is going to be a constant battle that the river will eventually win, and it will be an expensive one for the city to fight in perpetuity, if they want to maintain an artificial side channel like the mill race. That land is not stable, and much work will have to be done to seal the mill race if it is to be somehow temporarily saved, till the next flood. The original diggers of the mill race long ago did not know as much as we know today about how rivers react long term to man-made channels creating short-cuts across a river bend.
- A total 126 Texas wild rice stands were mapped in the San Marcos River between the old walking bridge in Ramon Lucio Park and Cape’s Dam. Only 16 small stands were located in the backwater area above Cape’s Dam and NO Texas wild rice were found in the Mill Race. The field data demonstrate that area influenced by Cape’s Dam is not providing conditions suitable for healthy stands of Texas wild rice. The field data also demonstrate the Mill Race is not providing any ecological benefit to Texas wild rice. Over 50 percent of the aquatic vegetation in the Mill Race is the introduced non-native Hygrophila.
- The Mill Race was extensively sampled with seining nets and underwater observations with snorkel and scuba. A total of 649 fish were collected in the Mill Race represented by 17 species, of which 70 were non-native species. Over 66 percent of the fish were mosquito fish. Less than 9 percent were sport fish and dominated by sunfish species. The data does not appear to support the contention that the Mill Race has a high-density sport fishery as claimed. A total of only 13 fountain darters were collected in the Mill Race and all were within a few hundred meters of the San Marcos River. There was no evidence of fountain darter reproduction within the Mill Race based on fish sizes collected. The direct field observations do not support the view that the Mill Race provides extensive high-quality habitat that is being extensively utilized by fountain darters.
- Water quality sampling along the length of the Mill Race shows increased water temperature and reduced dissolved oxygen compared to the main stem San Marcos River. This is a common effect of slower moving water. These slow water conditions affect native fish and wild rice, and is more favorable for non-native species.
San Marcos Record articles and videos by the dam advocates (those wanting to save the Cape’s Dam) were circulated on social media, saying that U.S. Fish & Wildlife Service had used wrong measurements of the height of the dam. And claiming that this was done in order to “get away with” lesser permitting requirements. We at SMRF know this to NOT be the case. To understand how a dam is measured, it is essential to understand how dams affect rivers, causing the riverbed to be variable in depth downstream of them.
- When water pours with great turbulence over the top of a dam, it scours out the riverbed just below the dam. It washes away whatever soil or gravel is below the dam, the way a fire hose would. This is the reason that dams fail, since eventually the footing of the dam is also eroded away.
- The Cape’s Dam, which is a pile of rock rubble with some wood and steel posts sticking out here and there, really averages the 3.7 ft that U.S. Fish and Wildlife Service engineers measured, but there are deep holes dug out downstream of the dam in several places by the eroding process described above. USFWS will remove only the rock rubble of the dam (excavation line down to 546 ft, no deeper than 6 ft). The dam averages less than 4 ft tall and 100 ft in length. The dam advocates are misunderstanding the scope of the dam removal, and what the actual riverbed is, as well. Perhaps they are measuring a hole downstream of the dam.
- TCEQ (Texas Commission on Environmental Quality) does not regulate dams that are less than 6 feet high and have less than 50 acre-feet of water stored behind the dam. Cape’s dam is well under that. There are several scenarios that were checked out, which TCEQ regulates for safety reasons. No matter what the claims are about measurements, the dam does not meet those TCEQ safety thresholds for a dam definition. TCEQ does not classify it as a dam, claims no authority over the project and has written a letter to say that to USFWS.
- Texas Parks & Wildlife (TPWD) and the US Army Corps of Engineers (USACE), have no such size requirement of the dam, TPWD is only concerned with the amount of sediment to be removed with the rock rubble, which is below 1000 cubic yards. Mike Montagne of USFWS discussed this with TPWD and they are fine with the USFWS plans, and the amount of sediment that could be removed. Sediment that has built up in a long stretch of river upstream will not be removed, instead it will be allowed to gradually move downstream to shape the riverbed by natural river rises.
- The dam is now very snaggle-toothed in its appearance since floods have almost washed it away. In other words, it has high and low piles of rocks left. Once the dam rubble is removed, the riverbed will adjust, deepening in places, and filling in some places with the sediment that has backed up behind the dam over the years. It will become a more natural riverbed shape. Deep pools will remain, according to the model run by Dr. Hardy and other scientists, and there will be good connection of river flow between those deep pools, with sufficient depth to support good recreation with flowing water. Without the dangerous rubble and steel in the way, the river will be SAFER for recreation. Portaging around the dam will no longer be necessary. We know of people who have been injured going over the rubble and steel of the dam accidentally in kayaks. It is important for public safety reasons to remove the dam “remains” left in the riverbed.
- All the large stretches of lake-like still water in San Marcos created by other dams (and that covers a lot of the river in town) will continue to have still water, especially close to Rio Vista dam/falls. But if those are not enough still places, and a very still pool is needed for a certain types of beginning lesson for kayaking and scuba – those opportunities currently are available in Spring Lake for paddling, scuba, and scuba for people with disabilities. More educational opportunities could be added in cooperation with the university and their instructional partners, though because of the sensitive nature of the Spring Lake habitat, there is limited access to the lake each day, and specially trained instructors ensure students leave no impact. These trained instructors ensure their lessons incorporate in-depth understanding of the significance of the habitat and use only certain spots for access. For those who love the river and want it to be cared for, these special precautions historically, have not been a problem.
We realize this more natural river flow, once the dam is removed, will be good for recreation and better for endangered species and other inhabitants of the river, like fish, as well. USFWS is planning some boater and swimmer access points that will be built during the dam removal project, as part of the project. This will save time so the park can be opened as soon as possible, without the city having to go through another permitting process to build these access points.
Thank you for the opportunity to put the record straight, and we will continue to work on correct information to distribute re the dam removal project. Our community needs to hear both sides.