DELTA STEWARDSHIP COUNCIL: Update on the Science and Management of Aquatic Weeds in the Delta

Invasive water hyacinth clogs a water channel in the Delta.

Panel highlights actions of multiple agencies to control the invasive aquatic weeds that clog the Delta’s waterways

Invasive aquatic vegetation in the Delta has dramatically expanded over the last decade, adversely impacting recreation and navigation, and reducing the quality of habitat for native species. Dramatic increases in invasive aquatic vegetation in the Delta have occurred over the last decade from 7,100 acres in 2008 to 11,360 in 2014, predominantly due to expansive growth of three species: water hyacinth, water primrose, and Brazilian waterweed.

At the December meeting of the Delta Stewardship Council, councilmembers heard a panel presentation on actions being taken to combat the problem. Invasive aquatic weeds are addressed in Delta Plan policy ERP 5, which requires avoidance of introductions of and habitat improvements for invasive nonnative species; and in Delta Plan recommendation ERR 7, which calls for prioritizing and implementing actions to control nonnative invasive species. Trends in coverage of nuisance aquatic vegetation are also tracked through one of the Delta Plan’s performance measures.

The recent proliferation of weeds has drawn increasing attention to ways research and science can inform management activities. “In 2015, the Delta Interagency Invasive Species Coordination Committee was established as an interagency forum to coordinate and communicate activities involving invasive species among federal, state, local, academic, and other stakeholder parties,” said Maggie Christman. “This group formed the planning committee for the 2015 symposium on invasive aquatic vegetation that was held jointly by the Delta Science Program, the Delta Conservancy, and UC Davis. The Committee is beginning preparations now to hold another symposium next year.”

“Following the last symposium in 2015, a synthesis paper has been prepared by Jenny Ta, associate specialist at UC Merced working with Joshua Viers, for the online open access journal, the San Francisco Estuary and Watershed Science,” Ms. Christman said. “This paper summarizes our current state of knowledge of aquatic weeds in the Delta, and provides direction for future coordinated research, management activities, and policy. The paper describes management tools that are currently in use or under study in the Delta, but discusses how effectiveness of these have been hindered by a complex regulatory structure, a lack of a consistent monitoring program, specific regulations that restrict treatments in space and time, and funding cuts. The paper concludes with a set of recommendations through which we could begin addressing some of these issues.”

Ms. Christman then introduced the panel: Lynn Sadler, Deputy Director of the California State Parks Division of Boating and Waterways; Dr. Louise Conrad, a program manager at DWR and chair of the Interagency Ecological Program’s new aquatic vegetation project workteam; and Dr. Patrick Moran, a research entymologist at the USDA Ag Research Service and director of the Delta Area Regionwide Aquatic Weed Project.

LYNN SADLER, Deputy Director of the California State Parks Division of Boating and Waterways

Lynn Sadler began by saying the California State Parks, Division of Boating and Waterways is the lead agency to cooperate with federal, state, and local agencies. “Our role is to control,” she said. “For example, water hyacinth has never been eradicated in history; we don’t expect to eradicate it. Our goal is control.”

They recently received permission to treat water primrose, an invasive weed that has proliferated to the point it was blocking sloughs and waterways. Water primrose, is a floating aquatic species, but unlike water hyacinth, it grows up onto land, onto buildings, over trees, and even on top of the water hyacinth. “So not only couldn’t we treat the primrose, we couldn’t treat the water hyacinth that was under it,” Ms. Sadler. “Now that we have the ability to treat, we’re expecting to be able to knock that back to the point of control – that’s our hope.”

Another aquatic weed that will soon need to be controlled is pennywort and fanwort. “Pennywort will be especially interesting because it is a native and fish like it, but it also is proliferating to the point that it is blocking waterways,” she said. “I think that one is going to be one of the more interesting of our challenges.”

“We control for public health, the environment, and the economy,” she said. “For public health, that’s pretty straightforward. You work with local agencies, there is science to back it up, and we manage according to that. For the environment, the same thing. The more difficult is the economy.”

Their available tools are chemical treatments, mechanical harvesting, biological controls, manual removal, and mapping.

Ms. Sadler presented a map of the project areas, noting that there are environmental compliance protocols and documents that govern what they do, and there are species, such as the giant garter snake, Delta smelt, steelhead, and salmon that are the drivers for those environmental compliance protocols. They do water quality monitoring before and after treatment so they can monitor the effect that the treatment is having, and building a body of knowledge to inform future practices, she said.

There are a number of treatment limitations. Ms. Sadler presented a map, noting that the area above that line cannot be treated before June 1^st, and they can’t use 24D in order to protect fish. “Of course we support that, but it creates a bit of a challenge because water still runs downhill, so all of that area not being treated serves to make it more difficult to protect what we are treating before that time,” she said.

There are other treatment limitations, due to agriculture, endangered species, fish columns, water diversions. “We created this graphic to show that by the time we take care of all the various issues, there’s actually very little available left that we can treat,” she said. “For example, when water hyacinth is not treated and it’s hot outside, that hyacinth will double in 10 days, so those are some of the challenges that we are up against.”

For floating aquatic vegetation, Ms. Sadler said they are on target to treat the same acreage as last year, which was the highest in their history and this in spite of the fact they lost a month to weather. “Our efficacy was moderate to high so we’re feeling pretty good about that,” she said. They are finished with the submerged aquatic vegetation program for the year.

This year, they added mechanical control as a treatment method. Ms. Sadler presented two graphs, one for biomass harvested and one for acreage. “The biomass is slightly less this year, which is encouraging so it’s not as dense, so maybe we’re making a bit of headway,” she said. “We had estimated that acreage covered with water hyacinth appears to be about 20% less; that’s not a perfect metric, because if it’s not as dense, but it is a metric that we have, so we’re hopeful that perhaps we made a dent and are beginning to be on downhill side of this.”

They have a toxicology study in process that is studying the toxicological effects of new herbicides on Delta Smelt and their food web. The study will determine if the herbicides they are using can be changed. The study will hopefully be completed next year.

“What is different this year that we think has contributed to our success is that we have 7-8 new field staff, 3 new environmental scientists, and a toxicologist,” Ms. Sadler said. “But especially important, we have four new boats and crews to go on them, so we can have more crews out working at any given time. We also have a four year harvesting contract. So we have more resources, and with those more resources, we have the time and the people that allows us to build our partnerships.”

They have a number of partnerships with federal, state, and local agencies. “We are working with UC Davis, USDA, and all of our partners to see if we can be smarter,” she said. “We focused on nursery sites this year, and we will know in a couple of years if that made a difference.”

They also contracted with the California Conservation Corps to train members in weed control.

“This year, we’re engaging all partners, not just in public health and the environment, not just government agencies, but we’re working with the Chamber of Commerce, private individuals in marinas,” Ms. Sadler said. “We are aware of some of the economic drivers for those businesses and we’re working to try and help there. … We have been asking individuals to send us photographs with locations to help us get sort of a early warning system when hyacinth are moving, and I like to think those efforts are not only helping us get ahead of the hyacinth and controlling them, but also being more focused, going where we’re needed the most or at least wanted the most, and so that’s been a change this year as well.”

Ms. Sadler presented a two hydroacoustic maps of Discovery Bay, the one on the left from October of 2014, and the one on the right from February of 2016. “As it relates to submerged aquatic vegetation, blue is good and any other color is bad, as you can see on the left, bad. However, on the right, I think you can see that things have improved dramatically.”

The biological opinion, which gives the Division permission to treat is expiring in the coming year, so they are in the process of preparing a new biological opinion which is scheduled to be finalized in the fall of 2017.

Division of Boating and Waterways spraying for water hyacinth in the Delta.

They are also preparing an Aquatic Invasive Species Management Plan for the Delta. The goal is to have maximum flexibility, Ms. Sadler said. “We can plan to treat the Stockton waterfront on any given day, and when we get there, the hyacinth’s floated out, so it’s not an issue,” she said. “I can plan today to treat Discovery Bay for a species that when I get there, it’s not there, but over here is something more, so the ability to remain flexible will be our goal.”

“The concepts that guide the program design are that we want to remain collaborative, science-based, we want to remain adaptive with the widest possible range of tools and flexibility, and we’ll include mapping, monitoring, and performance metrics,” she said. “And your input matters. Please watch our website for opportunities to engage. Please feel free to reach out to me with any comments you might have for how you would like us to prioritize our programs.”

Councilmember Susan Tatatyon asked what is done with the hyacinth and primrose that is treated and harvested?

“If it’s treated, the goal is that it essentially dies, rots, goes to the bottom and just serves as either a nutrient or a sediment,” said Ms.Sadler. “If it is harvested, it has to go somewhere. It’s very heavy; it’s 97% water. It can compost, but it’s not a great compost, it’s not high quality, and it’s apparently not good for feed. There are some folks looking at its viability for biomass conversion, but it doesn’t look like it’s going to be wonderful for that, so what we tend to do is compost it somewhere. We worked with some farmers who have taken it, we are working with the Nature Conservancy, they have a section of land that is low and tends to be a little swampy, and so we’re using it for fill there for them. We even have a situation where we worked in a park, they wanted to close an illegal road that had developed, and so we put four feet of water hyacinth on that.”

“We need places to spoil,” Ms. Sadler said. “It’s not just driven by the nature of the place where we put those spoils, but also where it is and if we can get that heavy equipment on that particular levee, and a lot of them cannot take the equipment that’s that heavy … If you know of landowners who are willing and able to provide places for us to spoil, that’s important, and we need a lot of them, because even 5 miles away; those boats are going 2 miles an hour, they are not fast, so you need them fairly close together or you lose so much time in the harvesting that you don’t get enough done in the course of a day. So that’s what we do with it, and that is something that we definitely need help with.”

DR. LOUISE CONRAD, Program manager at DWR

Dr. Louise Conrad, program manager at DWR, is also chair of the Interagency Ecological Program’s new aquatic vegetation project workteam. She discussed the activities of the new workteam as they relate to the call for enhanced aquatic weed control in the Delta smelt resiliency strategy that was released in July of 2016 by the Resources Agency.

IEP workteams are created with the goal of providing an open forum for scientific progress on a particular topic, and many of them here are really focused on fish, particularly salmon, she said. The Aquatic Vegetation Workteam was started in the fall of 2016. They have had two meetings so far; the first was a kickoff meeting where they discussed specific activities and needs, and the second was a presentation on the current approach to aquatic weed management.

The workteam is focused on three areas:

Forum for coordinating scientific research: At the first meeting, they had representatives from 15 different agencies spanning federal, state, nonprofit, water contractor, and university groups; approximately 30-40 people were in attendance. “The hope is that we want to keep the scientific research really focused on what are the management needs, and by engaging this broad group, we hope that we have a good model for success in that way,” Dr. Conrad said. “Other project workteams within the IEP have been a great source for producing sound study designs and producing scientific products that can further the science in the management.”

Guidance for a consistent monitoring program: There isn’t a consistent monitoring program currently setup for aquatic vegetation, so the project workteam will be providing guidance for putting together a sound, consistent, and feasible monitoring program. The image on the slide is an aerial image of Franks Tract; the left image is 2014, the right image is 2015, and the red depicts aquatic vegetation. The image is collected by low flying aircraft and then analyzed to determine the coverage of aquatic vegetation. “This shows you that a big change has happened in short periods of time,” said Dr. Conrad. “We need to be able to track this, we need to be able to do it at varying spatial scales, from one water body to the whole region. We don’t yet have a program to do this; this has been opportunistically done when funding has been available.”

Support evaluation & improvement of aquatic weed management efforts: “We hope that this workteam can be acting in part as one of the scientific arms for the Boating and Waterways Program,” she said.

One of the reasons the project workteam was started this year was that the Delta smelt resiliency strategy, released in July of 2016 from the Resources Agency, called for enhanced aquatic weed control action. The strategy specifically called on the Department of Water Resources to coordinate with Division of Boating and Waterways to increase the treatment of aquatic weeds in the Delta to maximize benefits for Delta smelt, and that the action will take place in 2017 and 2018.

“So we want to engage this group to really put together a smart responsive action that’s called for here,” Dr. Conrad said. “It’s being funded by the Department of Fish and Wildlife, it is right now $1.8 million that we have to treat weeds within both of these years. That needs to cover the monitoring of the action, as well as remote sensing with low-flying aircraft to produce maps of aquatic vegetation.”

Dr. Conrad said they are thinking strategically about how to utilize the funds, taking a considered approach. They want to work actively with the Division of Boating and Waterways to think about what they are already covering, to think about where are Delta smelt going to be, and within that distribution of Delta smelt, target the locations for doing enhanced aquatic weed control.

She presented a map of treatment areas that were treated at least once between 2013 and 2016; the purple area represents treatment of water hyacinth and the green area is Egeria densa or Brazilian water weed, one of the worst submerged weeds. Delta smelt habitat is generally the northern and western portion of the Delta. “The broad Delta-wide map is telling us there’s treatment happening for floating aquatic weeds but not as much for submerged aquatic weeds in this region,” said Dr. Conrad. “So this may be an area that we look at for performing this action and doing all of the monitoring associated with that. We need to know if this is going to continue, if this problem is still here in 2016.”

Dr. Conrad was out at the end of November looking at the weeds, and already there were weeds; very healthy looking for the end of November, she said. “DWR has paid for another remote sensing aerial imagery to be collected in 2016, and so that imagery is now being analyzed and we’re looking at that in order to make a final determination on where to do this action for the Delta smelt habitat,” she said.

From the 2017 control action, Dr. Conrad said they have given some thought as to how the system and the ecology of aquatic weeds work; the box and arrow diagram on the slide is the conceptual map for their thinking. So the predictions are that if they treat aquatic vegetation with herbicides, which is the main tool in the toolbox for submerged species, they would expect that the biomass of aquatic vegetation will go down. They want to monitor to determine how long the treatment is effective and how fast the weeds grow back.

They expect the turbidity to go up because aquatic vegetation is generally trapping sediments, which is thought to be a bad thing for Delta smelt as they like turbidity; so the main improvement for Delta smelt as a result of treating aquatic vegetation is that the turbidity would increase, and perhaps water temperatures would decrease. They also expect there will be a food web benefit, because vegetation competes with phytoplankton, which is the base of the food web for Delta smelt, so if removal is effective, there would be a positive response on the food web.

“This is a two-year action and we would like to apply this adaptive management wheel to our project,” said Dr. Conrad. “We will be monitoring all these aspects of both water quality and the food web and the weeds themselves, and then thinking about what was effective, what was not effective, and what can we do differently and refine the action for 2018.”

Dr. Conrad said they had a lot of planning and mapping to do; they will be putting together a complete study plan for the project work team to review in January.

DR. PATRICK MORAN, USDA Agricultural Research Service Exotic and Invasive Research Unit

Dr. Patrick Moran with the USDA Agricultural Research Service Exotic and Invasive Research Unit then discussed the integrated Delta region area-wide aquatic weed management project. He credited the efforts of Ray Carruthers, Mary Piehpo in Contra Costa County, Larry Ruhstaller in San Joaquin County, and other local legislators to highlight the need for federal involvement to help combat the problem with invasive weeds with a scientific approach to protect water resources, natural ecosystems, commercial and recreational navigation, public health, and Delta economies.

The mission of the USDA’s Agricultural Research Service is to conduct research to solve problems in agriculture, and to enhance and protect natural resources that are essential for agriculture and healthy natural ecosystems (water, soil, air). They work to ensure high‐quality, safe food and other agricultural products, enhance the natural resource base and the environment, sustain a globally competitive U.S. agricultural economy, and provide economic opportunities for rural citizens, communities and society as a whole.

“An important thing is we do that our research is to be transferred to stakeholders and users,” he said. “We have to publish our research in the scientific literature and get it peer reviewed, but we’re supposed to do research that is really applicable to real world problems that can be applied to these problems.”

Before the project was started, the USDA Agricultural Research Service since 2001 has been the federal nexus for the Division of Boating and Waterways with their permits with the US FWS Service and the NMFS, essentially shepherding the biological assessment from the Division to those services. They facilitate the review process, the communication, and any amendments that might be needed; they also play a key role in submitting the annual report that’s required by the biological assessments.

“We have been involved in research for awhile in the Delta looking at aquatic weed control, status of the aquatic weeds, and different potential new control technologies,” said Dr. Moran. “This project came about as a result of the need to expand beyond what we were doing in a relatively limited sense and get more agencies involved in an approach that would cover the entire Delta and implement new technology.”

The USDA ARS has a national area-wide pest management program that focuses on all kinds of pests, including insects and major invasive weeds, but this is the first project to focus on aquatic weeds. “Like all area-wide projects, they address major environmental and economic problem invasive pest species,” he said. “They are meant to bring together a number of different entities of scientific experts from the USDA ARS as well as other scientific agencies, natural resource managers, the stakeholders, the public and private landowners, and different government agencies such as the Delta Stewardship Council, which has a role in protecting the Delta’s natural resources.”

USDA‐ARS has been conducting research to develop new technology to improve aquatic weed control programs in the Delta and throughout the western U.S. They have been testing and development of new integrated chemical, physical, and cultural control methods as well as discovering and testing of new biological control agents.

When the project started, it primarily focused on water hyacinth, Brazilian water weed, and Arundo. These three weeds were the basis for the justification for the initial proposal for the project because they are all widespread and causing big problems, and there were multiple control approaches available but they needed to be integrated and improved to be better implemented in the Delta.

“There are multiple agencies concerned about these weeds and involved in their control, but only Division of Boating and Waterways has the permits to do the widespread herbicidal treatment and mechanical treatment,” he said. “The USDA ARS obtains permission to do biocontrol when possible, but there are a lot of agencies that aren’t necessarily involved in the hands-on control but are very concerned about the weeds because of they are threatening the resources of the Delta. So it seemed like a good justification.”

The broad objectives of the project are:

To model growth of individual plants, and growth and movement of aquatic weed populations (water nutrients, water flow, agricultural land use). “One is to look at the growth of individual plants and populations of the aquatic weeds, and model that on the basis of scientific knowledge about weed growth, such as the effects of nutrients on weed growth,” he said.
To detect aquatic weeds remotely using satellite and aerial imaging and track current and seasonal aquatic weed population size. “There have been efforts in the past to do remote sensing in the Delta and detect aquatic weeds, but it’s received piecemeal grant funding – on again off again, so the idea is to bring about a more consistent sustained approach at looking at the weeds and detecting them, and also to integrate some of the work that Division of Boating and Waterways is doing with bioacoustics mapping of submerged aquatic weeds,” he said.
To prioritize aquatic weed locations for control based on plant/population growth model, remote sensing, and critical water resource needs.
To implement new and improved methods for control of water hyacinth, egeria and arundo in the Delta; Adaptive Integrated Management
To assess impacts of areawide-implemented control on weed infestations, associated organisms such as mosquitoes, and water resource availability, model economic benefits, and communicate project activities and successes. “We have to assess the success of the control program using some of these technologies, such as remote sensing,” Dr. Moran said. “We also have to look at the environmental effects of the program and of the weeds themselves, for example, effects on dissolved oxygen, effects on habitat for Delta smelt, effects on mosquitoes as aquatic weeds and mosquitoes have an interaction. Mosquitoes can vector diseases such as West Nile virus, and so there’s a tie in with this project to the mosquito vector control districts that have a critical human health mission in the Delta.”

He presented a slide which was more for stakeholders and the public that explains the acronym for this project, DRAAWP. “The key thing is the water droplet,” Dr. Moran said. “USDA ARS is in this project first and foremost because of the water resources. We know that navigation is important, as are human health and the endangered species, but water resources we know are critically important here in California to sustain a healthy agricultural economies in the Central Valley and throughout the state, as well as provide drinking water supplies for the cities. That’s probably the most important reason why USDA ARS is invested in the project.”

Other factors motivating the development of the program was that although there had been sustained control efforts, they haven’t been able to achieve long-term sustainable control to the level at which the economic and environmental problems go away. “We still have had in the past problems with these weeds – severe problems for Delta economies and potentially for the listed species,” said Dr. Moran. “Both for the aquatic weeds and for the Arundo, which is an example of a riparian weed growing close to the water and having major impacts. And all of these weeds can have an influence on flood control; there is a major potential threat to flood control caused by both the aquatic weeds and the arundo.”

The project is in its third year with the first round of funding received in 2014. Typically these projects are funded for five years, but it’s a year to year process, depending on whether funds are available and whether they can show progress each year. They have a benchmark of potentially a 20% reduction in peak annual coverage of water hyacinth from the start of the project.

“We also have this shift in timing of the peak coverage from mid- to late- fall to summer,” said Dr. Moran. “That may not seem like a big deal at first, but if you think about when the pumps in the south Delta are turned on, the seasonal barriers are removed, the changing of that timing of the peak coverage is actually potentially very important for water conveyance from different parts of the Delta to where those pumping facilities are.”

Dr. Moran said that the control of submerged weeds, the Brazilian water weed and curly leaf pondweed has been improved dramatically through a smarter herbicide treatment regime, and improved monitoring. They are working with the Sacramento-San Joaquin Delta Conservancy, which is receiving funding for a chemical pilot control project and new biological control agents for control of Arundo. They are also working with UC Davis on a bioeconomic model to track the costs of the aquatic weeds, the damage they cause to marinas, the cost of the state agencies to control them, and to predict the benefits of improved control for Delta economic systems.

The NASA Ames Research Center is receiving funding under this project for LANDSAT remote sensing of water hyacinth in the Delta. “This chart shows the annual peak, seasonal change in the coverage, but shows a decrease in the peak, 2016 versus 2014, and a shift in timing from the late to mid fall into more of the summertime,” he said.

Dr. Moran explained that whenever the sky is clear, LANDSAT can provide data every two weeks it flies over the Delta. NASA has developed an automated processing program to look at the images and convert them into acres of water hyacinth. They show relatively low amounts of water hyacinth early in the season and it comes back in the heart of summer with large populations; the Division of Boating and Waterways is out there working hard to treat them at that time. There is then a big decrease as they get to the end of the season. “This is not just accidental,” he said. “Two years ago, there still would have been a lot of hyacinth out there, even late in the season. The plant is pretty hardy and can withstand cool conditions, but with Boating and Waterways improved efforts and integrated adaptive control, it has led to this decrease.”

One of the projects that Dr. Moran is working on is biocontrol, and he has one biocontrol agent, the planthopper, that he has been working with for water hyacinth. He noted that within the Delta, they have to go through the same regulatory process with the US FWS and NMFS, so they are hoping to incorporate that into the next biological assessment. “In the meantime, I’ve been doing work outside the Delta and I’ve got this insect established at limited sites outside the Delta,” he said. “It’s a little too early to evaluate the impact, but it’s an example of new control technology being used as part of this project. It’s being used at a new site south of the Delta in Merced County.”

Dr. Moran said one of the motivations for the project was helping the agencies to optimize their control methods. They have assisted in increasing the control by using the NASA satellite imagery to detect nursery sites for water hyacinth that can be targeted for control at strategic times, and using bioacoustic methods for increased year round surveillance for Brazilian water weed and curly leaf pondweed. They are using information from the scientific experts on how the weeds grown, and tagging plants with GPS trackers to see where they go.

They have also had a lot of dialog with local stakeholders, and the different federal and state agencies.

There are a lot of state agencies involved, even the agencies that aren’t necessarily involved directly in control, but they are working to interact and share information. “The new invasive plant work team with the Interagency Ecological Program is a good example of a team coming together around this problem,” Dr. Moran said. “This is all designed to help protect the economic and environmental values that we have in the Delta: the boating, the endangered species, the water conveyance, the natural beauty, and everything else.”

Dr. Moran concluded by pointing out the many meetings and projects they’ve inspired or been involved with. “We’ve had groups that we feel that were at least partially inspired by the Delta area region-wide aquatic weed project, such as the interagency group that the Delta Conservancy started. I gave a presentation last year to the Delta Plan Interagency Implementation Committee which got a lot of attention … We think we possibly helped leverage new state resources for the Division of Boating and Waterways that they’ve been able to use to increase their control capacity. The Central Valley Regional Water Quality Control Board asked us to be involved in a white paper on nutrient modeling, which now they are turning into a potential grant program to fund nutrient studies in the Delta and interactions with aquatic weeds. We had the one day symposium that the DSC put together last year, and just this year, we had a scientific symposium at the Bay Delta Science Conference. We had 10 speakers and about 50-70 people there throughout. Most of the speakers were people funded in part by this project.”

“So I’m going to stop there … “

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