I'm at least going to email John and see if there is any way to petition or something to get hydrilla taken off the invasive list. I dont think that will stop the spraying on rayburn and Toledo though, even caddo. So more would have to be done.

Agreed, and spraying isn’t the only solution. On Guntersville they have a mechanical harvester so they can maintain the grass without eliminating it and maintain access. I’d like to see this on LCRA lakes and Conroe rather than the combination of spraying AND way over stocking with carp. On Toledo and Rayburn the target of the spraying is more for Salvinia, which could be treated with weevils.

They had mechanical hydrilla harvesters here in East Texas but quit using them years ago.

Guys, I sent an email to John and this is his response. They are doing more than we think and there is some good info in this email. He also mentioned that they had a meeting with USACE yesterday and he will try to post up about that. Based on the his info, the future sounds like it will get better from a management standpoint for sure. I will say, my opinion still is that the applicators are over doing it in some cases and causing some of the issues. If that turns out to be the issue atleast it can be identified and then fixed rather than so much going wrong that it's impossible to fix. It's a long email but worth the read, it's very informative.


Howdy Keith,

Thank you for reaching out to discuss the vegetation control issue further. Being an avid bass angler myself and former TPWD fisheries management biologist for nearly 20 years in South Texas (I transferred from the Mathis office to the Aquatic Habitat Enhancement office in February 2016), I understand the concern of impacts to non-target vegetation when herbicides are used. Additionally, I understand how important hydrilla can be to a largemouth bass fishery. Choke Canyon Reservoir, one of the lakes I managed while in Mathis, was a phenomenal bass fishery when hydrilla was abundant. I know of eight 15+ lbs fish caught in 2009-2010 and talked to several anglers that had 50+ lbs with their best five. Hydrilla does make great habitat and bass fishing fun.

Hydrilla will always be listed as an invasive species because it is a non-native plant and can create problems in some water bodies, especially the smaller, shallower lakes like such Sheldon Reservoir (60% covered in 2020) and Lake Raven (55% covered in 2017). This is also the reason hydrilla is listed as a prohibited species in Texas. However, just because it’s classified as invasive or prohibited does not mean that TPWD treats hydrilla on all water bodies. On some lakes, such as Sam Rayburn, Toledo Bend, Lake Fork, Choke Canyon, and Lake Amistad, hydrilla has proven to be a critical component in creating phenomenal largemouth bass fisheries and is not treated. Ultimately, the determination as to whether hydrilla is beneficial or problematic is the decision of the fisheries biologists for a given water body. For questions regarding hydrilla and hydrilla management you need to contact the fisheries biologist for the lake in question.

When vegetation is designated problematic by the fisheries biologist, the Aquatic Habitat Enhancement (AHE) team will work with the fisheries biologist(s) on the creation of a vegetation management plan to treat the problem area(s). Minimizing collateral damage is extremely important in the development of all vegetation management plans and the focus is to only treat what needs to be treated. For example, the current hydrilla control plan for Lake Raven is to treat all vegetation, hydrilla included, on the shoreline adjacent to the state park campsites (increase shoreline access) and treat hydrilla in the paddleboat cove (increase paddleboat access in the lake). The other two coves also have hydrilla, but it is less of access issue thus the objective here is to use an herbicide to create a boat lane through the hydrilla mat. Finally, hydrilla on the shoreline opposite of the state park is not treated and left for fish habitat. In 2020, TPWD treated a total of 241 acres of hydrilla across the state. All these treatments focused on boat ramps, designated swimming areas (hydrilla has been blamed for several drowning in the last few years), campsite access, and creating boat lanes through thick hydrilla mats. In the five years I have been the team leader for the AHE, there has never been a management plan to eradicate hydrilla from a public water body.

I went back read my original post and cannot find where I may have led you astray on herbicides are either over applied or the herbicide isn’t target specific. Herbicide use is a highly controversial topic throughout the world. I will agree that herbicides were the primary cause of the reduction of torpedo grass (haygrass) in Lowe’s Creek as well as Indian Mounds and a few other places in 2016-2017. As would be expected, this was very concerning and not what my team, the fisheries management team, or the anglers wanted. We met with the contractors and instructed them to start focusing on only treating mats of giant salvinia rather than spraying all salvinia plants encountered. At the time the giant salvinia was being treated with glyphosate, a systemic herbicide that is circulated throughout the entire plant. Glyphosate is not effective in the water column as it is rapidly broken down by clay and organic matter, thus having no impact on hydrilla, coontail, or other beneficial, submersed plant species. However, we suspected and later confirmed through an experiment that glyphosate was killing the torpedo grass. After learning this, we switched from glyphosate to diquat dibromide. In the experiment, we found that diquat would burn the top of the torpedo grass but leave the submersed part of the plant untouched. The torpedo grass would recover and new growth above the surface was observed two weeks after treatment. We did not observe any impacts on other species such as hydrilla, coontail, or other submersed species either. Diquat is a contact herbicide meaning that it only impacts the part of the plant where the herbicide touches. It is not circulated through the plant like a glyphosate. The contractors began using diquat to treat giant salvinia at Toledo Bend in 2017. We use diquat on giant salvinia in many other lakes across the state, including lakes Sam Rayburn and Caddo, and does not affect the non-target vegetation in these reservoirs. This last summer we had the contractors switch herbicides from diquat to penoxsulam to prevent giant salvinia from becoming diquat resistant. We switched the contractors back to diquat later in the fall as water temperature drops and plant metabolism decreases.



The herbicides used to treat giant salvinia on Toledo Bend are mixed in a tank with 100 gallons of water and sprayed over one acre of giant salvinia. For diquat, the mix is 0.5 gallons (0.5% solution) of diquat per acre of salvinia. Diquat can be used to control hydrilla but it must be injected into the water column and applied at a higher rate than what we are using on the giant salvinia. When treating giant salvinia with diquat, the herbicide is sprayed onto the mat. Some diquat will drip from the plant into the water but it is not enough to kill submersed vegetation as it is quickly diluted. Penoxsulam is being applied at 4 fluid ounces per acre and like diquat can be used to control hydrilla and other submersed species. But again, we are using it at a lower rate than needed to kill the submersed species and are applying the herbicide to the mat not the water column. Research has shown that herbicides are rapidly broken down in the environment by UV light (sunlight), microbes, and chemical reactions with dissolved molecules and organic matter in the water column. Typically, the half-life of diquat is less than 48 hours in the water column. While some studies show diquat can remain in the sediments for 160 days, it is not active as an herbicide.



The total amount giant salvinia treated annually on Toledo Bend has decreased substantially since the cold weather in January 2018. Nighttime temperatures fell to the mid to upper teens during that event and decreased giant salvinia in Texas by over 90% at the time. Herbicide treatments have been able to maintain the giant salvinia on Toledo Bend and elsewhere across the state where giant salvinia is not creating access issues. In 2020 we have directed the contractors to treat only from the North Toledo Bend WMA south to Martinez Creek. The purpose for decreasing the treatment area is we wanted to see if beneficial vegetation would return if no treatments were conducted in an area. Additionally, we found giant salvinia weevils south of Martinez, primarily in Housen Bay and Six Mile areas and wanted to see if the weevils could maintain control. As of now the weevils in Housen Bay and Six Mile are keeping the giant salvinia under control. In January we sampled weevils in both areas and found weevil abundance was high enough to maintain control. However, that could change this weekend as the weevils do not tolerate extremely cold temperatures. Unfortunately, the salvinia can tolerate colder temperatures than the weevil.



To protect the beneficial vegetation, we switched herbicides, had the contractors focus on only treating mats of giant salvinia, and recently decreased the treatment area on Toledo Bend. We know that herbicides rapidly bind to clays and organic material (leaves, sticks, etc.) and broken down to the point where they no longer function as an herbicide. The small amount of herbicide entering the water column around the mats of salvinia or water hyacinth will be quickly diluted and not impact vegetation. All these things should have allowed non-target vegetation such as hydrilla and coontail to persist and even expand on Toledo Bend. We treat almost 2.5 times as much giant salvinia annually on Caddo Lake (~7,300 acres a year) and beneficial vegetation, including hydrilla is abundant there.



I have had numerous discussions regarding Toledo Bend’s once abundant vegetation with the lake’s fisheries biologist. The best explanation we have for the disappearance of the main lake vegetation as well as the vegetation in the coves and bays is due to nature, primarily muddy water. In the Spring 2016, Toledo Bend experienced a large rainfall event that resulted in much of the main lake being covered with muddy water. For reference, water releases from the dam were near 200,000 cubic feet per second. By 2017 hydrilla and other submersed vegetation species were reduced to many of the coves and bays but spring rains in 2017 made most of these areas muddy. Housen Bay was muddy for several weeks in the Spring 2018. This same pattern has continued through 2019. Muddy water can be detrimental to hydrilla especially in the Spring when it begins to grow. I experienced this several times while I was a fisheries management biologist in South Texas. One instance occurred at Coleto Creek Reservoir as water level increased 3.5 feet in one day because of a large rainfall event. This left the reservoir muddy and resulted in a large kill of hydrilla and Eurasian watermilfoil, most of which has not recovered as of present. Sam Rayburn experienced a large, lake-wide water level increase in January 2019 that remained through most of March 2019. Much of the upper end was muddy for several weeks. There was a subsequent rise in June 2019, again creating more muddy conditions in the upper end of the reservoir. By January 2020 there was hardly any submersed aquatic vegetation above the Hwy 147 bridge, however it is slowly coming back. These events on Coleto Creek and Sam Rayburn occurred in only one year and had major impacts on the vegetation in both reservoirs. Looking back at Toledo Bend where the muddy water events occurred for several years in a row, it’s easy to see how these events resulted in mass reduction of aquatic vegetation lake-wide, especially when you consider how delicate hydrilla is when if first begins to grow in the Spring. My office was made aware of lily pads disappearing on Toledo Bend this past summer after being abundant in the Spring. Our herbicide treatment records show the last time TPWD treated Housen Bay and Six Mile was December 2019 and it was November 2019 the last time any contracted herbicide treatments occurred. My team investigated the report and observed moth larvae feeding on American lotus pads in Housen Bay a couple of months in July 2020. The lotus pads above the water or on dry land did not have any marks on them but the pads on the surface of the water had large chew marks that resembled the chew marks of the tomato hornworm. In several places, the larvae had destroyed the American lotus patch. Last fall, several states began reporting moth larvae destroying elephant ear from Louisiana to Florida. This may explain why we have seen decreases in other species Toledo Bend such as the American lotus. Remember native vegetation has natural controls to keep it in check and sometimes these natural controls can go overboard.



As you can see, there are numerous factors that can lead to decreased aquatic vegetation in a reservoir. We have and will always adjust our herbicide-based treatment plan(s) to preserve as much fish habitat. However, sometimes despite our best efforts to preserve aquatic vegetation, nature takes over and we lose the majority of vegetative habitat.



I remember hearing about the dead turtles, but I do not believe herbicides were the cause as TPWD and other agencies treat aquatic vegetation elsewhere in the state and the country and have not seen any issue with turtles. Also, all herbicides must be registered and labeled by the EPA according to the Federal Insecticide, Fungicide and Rodenticide Act (https://www.epa.gov/laws-regulations/summary-federal-insecticide-fungicide-and-rodenticide-act). Aquatic herbicides must be registered and labeled for use aquatic environments. Since the label must be approved by EPA too, then the label becomes the law for the use of that specific herbicide. Labels provide users with ingredients, safety precautions, human and animal hazards, environmental hazards, physical or chemical hazards, storage and disposal, product information, personal protective equipment requirements, water use restrictions (if any), herbicide application rates, and vegetation species affected. Thus, if there were cautions/warnings regarding use around turtles it would be on the label. The same thing for fish. The regulations are so specific that if a specific vegetation is not on the label, it cannot be used to treat that plant. This website will go into further detail about the aquatic herbicide testing, toxicity, and EPA registration (https://plants-archive.ifas.ufl.edu...e-testing-toxicity-and-epa-registration/). I have attached the Tribune label as an example. Back to the turtles, it was probably a viral or bacterial infection that killed them.



As I alluded to earlier, herbicides rapidly bind to clays and organic material and are broken down, bacteria, point they no longer function as an herbicide. Glyphosate and diquat can bind to suspended clays and organic materials in less than 30 minutes. According to the label, glyphosate is not effective on submersed aquatic vegetation because of the rapid binding. However, we learned it was extremely effective on torpedo grass at Toledo Bend. Glyphosate is a systemic herbicide meaning it is absorbed by the plant and circulated through the roots, killing the entire plant. This differs from the contact herbicides that only impact the area of the plant the herbicide contacts. Remember in our torpedo grass study on Lake Sam Rayburn we saw contact herbicides affected the part of the torpedo grass that was above the water, but the torpedo grass underwater was still alive and growing. Unfortunately, there is currently not an EPA approved herbicide that only targets giant salvinia or water hyacinth. We have a suite of herbicides available for use that specifically have giant salvinia on the label. Unfortunately, each of them can affect non-target vegetation too. We weigh all the options and consequences before selecting an herbicide to use.



It would be great for all of us to meet and discuss these things over a dinner one night but with Covid restrictions that is not an option. As anglers the best thing to do is talk and work with the fisheries management biologists, create a Friends of Reservoirs group (https://www.friendsofreservoirs.com/), initiate habitat improvement projects, and ask questions like you did with this email. Most of all please clean, drain, and dry your boat.



Thanks again for reaching out and I hope that I answered your questions completely but if not, please feel free to contact me via email or telephone.

Also, I'm looking into the friends of reservoirs. It would at least be an opportunity for some of the clubs or anybody to help put habitat back. I know it wont be hydrilla like the bass guys want but if we can get other native stuff going it's a help. Communication is key, if we just come on TFF and complain nothing will be accomplished. It doesn't take much to send an email, call someone, or stop by an office to talk. While I want to think TPWD should know everything going on on every body of water all the time, that's not the case. Plus, if the comments they always hear are from the non fishing crowd that wants all the grass and stuff gone, its natural that they start to think that is the prevailing thought. So the anglers need to step up. Atleast we can try and I'm all for taking another step kind of like they are doing in LA about the canals if things dont start to get better. After emailing John, I feel better about the direction they are taking for sure

Texas Parks and Wildlife Department’s local fisheries management and aquatic habitat enhancement offices both met with the U.S. Army Corps of Engineers (USACE) and the Lower Neches Valley Authority (LNVA), Wednesday morning to discuss the current giant salvinia management plan for Lake Sam Rayburn. The project is led by the USACE with funding provided by TPWD and LNVA. The plan only focuses on treatment and control of giant salvinia and water hyacinth. Hydrilla and torpedo grass (often called hay grass) are not part of this management/control plan. Excluding a rare treatment within swimming areas in USACE parks, there have never been any directed herbicide treatments of hydrilla or torpedo grass at Sam Rayburn.

Since 2009, the USACE vegetation management plan for giant salvinia and water hyacinth focused on problematic areas and used an integrated pest management approach. Herbicide treatments are conducted most frequently above the Hwy 103 bridge on the Angelina and Attoyac arms and above the Hwy 83 bridge on the Ayish Bayou arm. Giant salvinia and water hyacinth are treated above the bridge throughout the year with increased treatments in the Winter. Salvinia and hyacinth found in the rest of the lake are also treated, but typically only during a small window from mid-November through early February, using contact herbicides such as Tribune. Occasionally, when giant salvinia and/or water hyacinth became a problem anywhere below the bridges, the area(s) were treated in late Spring/early Winter. The herbicide treatment that occurred at Monterrey Park was part of the small window, Winter-time treatments and that area has been treated repeatedly over the last 12 years during the Winter. In addition to herbicide treatments, the USACE has used giant salvinia weevils as part of integrated pest management plan. The use of weevils is fairly widespread below the bridges and has shown some limited control over the years at Lake Sam Rayburn.

A few modifications were made to the giant salvinia vegetation treatment plan for Lake Sam Rayburn as a result of Wednesday’s meeting. The main one is the creation of “no spray zones” in the reservoir. TPWD, LNVA, and the USACE have agreed to set aside areas (selected by TPWD fisheries biologists) that will not be treated with herbicides and giant salvinia weevils will be used to control the giant salvinia. The one caveat is should the salvinia become too abundant or large mats appear in open water of these no spray zones, herbicides may be used to bring things back under control. There must be agreement among TPWD (both fisheries management and AHE offices), LNVA, and USACE before a treatment will occur and there will be a concerted effort to minimize impacts to non-target species. Other areas below the bridges will only be treated during the Winter using herbicides, such as diquat, that minimize non-target impacts. Again though, should salvinia become too abundant or large mats appear in open water of these areas, herbicides will be used to bring things back under control with agreement among the partners and efforts to minimize non-target impacts.

Winter-time treatments are beneficial to maintaining the control of giant salvinia and water hyacinth for several reasons. First, killing the plant in the Winter prevents it from becoming more of a problem later in the Spring and/or Summer and less herbicide is used. Second, most of the vegetation beneficial as fish habitat will have senesced back for the winter (leaf-off) and is not impacted by herbicides. This minimizes collateral damage to non-target species, especially when using a contact herbicide. The buck brush at Monterrey was in leaf-off (no leaves) and will not be affected by the diquat treatment. Finally, herbicide treatments add to stress the plant is experiencing because of cold weather. Giant salvinia and water hyacinth are both subtropical/tropical plants, native to South America, and become stressed in cold temperatures. Our local Winter-time temperatures are typically not cold enough to kill salvinia or hyacinth but will stress it. Adding herbicide to the stress can kill both species.

We have found the giant salvinia weevils to be a great tool in the management of giant salvinia when they survive the Winter. The weevils are not able to tolerate as cold of temperatures as the salvinia and weevil numbers decrease substantially in a typical Winter. In extreme cold weather events, we may lose all the weevils in a water body like we did at Caddo Lake in January 2018 and we could possibly do again this weekend and beginning of next week. Lake Sam Rayburn is at the northern edge of the winter temperature tolerance for the weevils on a typical year. Rarely have we seen the weevils eliminate the majority of giant salvinia in a water body. The few places it did happen it was temporary and the giant salvinia returned within a year. Those areas have been kept under control with a few herbicide treatments each year. TPWD is relying heavily on the weevils to control giant salvinia on Lake Nacogdoches since most of the salvinia is mixed with other vegetation. The weevils have kept the salvinia in check but TPWD still conducts 2-3 herbicide treatments a year to maintain control.

The current vegetation management plan was effective at maintaining control of the giant salvinia over the last 12 years while protecting beneficial plants such as lily pads, hydrilla, and torpedo grass. There were even a few herbicide treatments occurring in Veach Basin, Five Fingers, Caney Creek, Popher’s Creek and Harvey Creek in the past with no collateral damage to beneficial plant species. The changes to the treatment plan will begin immediately and could take a year or more to see results. If you have any additional questions please contact me via email or phone.

Are these "No Spray Zones" that are being created just for Rayburn or for other lakes like Lake Fork as well?

It's always hydrilla is an "invasive species" well ill be the bad guy here is say at one time the largemouth bass was an invasive species to. Now it's not thought of in that light. Why can't hydrilla be the same way.

John,

You have given good detailed information on how y'all have treated invasive grasses with different chemicals in many lake. However, you failed to mention the two time decimation of all grasses in Lake Conroe. Why can't TPWD use these principles you have talked about to control vegetation on Conroe instead of eliminating all vegetation in the entire lake? If herbicides can be used on the largest lakes in the state, whey can't they be used on a lake the size of Conroe? How come each time Asian Carp are stocked in Lake Conroe they are overstocked, even though the TPWD say their numbers are based on scientific studied?

Good question RKT! John, what about Purtis Creek, Cypress Springs, Jacksonville, and many others!

Good questions RKT. I didnt bring up the carp in my email, I guess mainly because I mainly spend my time on Rayburn and Toledo. That's one reason we should all be in touch with John or our area biologist. It might be beneficial to form a group of anglers so that we can bring all of the concerns from all over to TPWD and USACE. I thoroughly believe that the USACE and maybe TPWD hear more concerns from the people that dont want any grass rather than the anglers who do. If it seems like the majority doesn't want the grass then you cant really blame them for doing what they think the majority will want. We need to be a bigger voice for ourselves. Chance, I totally agree on the hydrilla but I get both sides. Think of the small lakes and waters that would be taken over if they didnt spray. Now that wouldnt bother me one bit but it does effect water supplies or other things. Places like rayburn and Toledo theres no worry, it wont ever get out of control. I do think theres a middle ground though and it should come off the invasive list. Taking it off that list shouldn't mean you cant control it where needs be but it should make it harder to eradicate it from lakes. I think the part TPWD would worry about is people then thinking they should start putting hydrilla in every lake and that may cause an issue. I think the carp are a viable method if used sparingly. I'm totally against putting chemicals in our water when there are other ways to control stuff. My opinion is use the beetles and only a few carp. Every lake has different needs though

John Findeisen, thank you for coming on here and discussing this with us. Sounds like you guys are learning from past mistakes and improving. Hopefully with this cold weather that is on the way this will put a halt to the spraying for awhile.

So will TPWD pinky promise not to spray ANY this year now that this cold weather will naturally manage the grass?

So to continue with my bass analogy. They were once an invasive species. The state set a bag limit and over time it's been modified to where it sits today. Now bass are no longer considered an invasive species. So why can't Hydrilla be viewed in the same light. Every single bass fisherman on here hates what they did to conroe but I'd wager every single one of us understands the Grass needed to be managed. They just did it thr wrong way. Entirely to many grass carp. A grass harvesting boat (a few really) would've made much more sense. Yeah might cost more but would've been more appropriate for everyone. I agree with you, there needs to be a fisherman led group that sits in these meetings and talks with all parties about our perspective. Thats the only way to go. If we just act like playground kindergartens nothing will ever get done.

What happened to all the grass harvesting boats they used to have?