Open water dreissenid mussel control projects: lessons learned from a retrospective analysis Authors: Angelique D. Dahlberg, Diane L. Waller, David Hammond, Keegan Lund, Nicholas B. D. Phelps --------------------------------------------------- TREATMENT PROJECT SUMMARIES --------------------------------------------------- Here, we include information on all open water dreissenid mussel control projects that are known to have occurred in North America. We contacted resource managers and researchers within the invasive species community, including The Invasive Mussel Collaborative listserv (https://invasivemusselcollaborative.net), staff from control product vendors (i.e., Earth Science Labs, Marrone Bio Innovations, and ASI Group Ltd.), and staff within agencies who have conducted treatments (i.e., Minnesota Department of Natural Resources (MN DNR), US Geological Survey (USGS)), and others identified by the initial contacts. Information included below was provided and reported by different control project managers. Information not included was not reported or not available. Note: ST = short-term (before post-treatment sampling or within one year) LT = long-term (after post-treatment sampling or after one year) IT = within treated area OT = outside of treated area NA applies to projects where 100% of the surface area or shoreline was treated (and there was no OT) ------------------------------------------------------------------------- Base Lake, Offutt Air Force Base (Sarpy County, Nebraska) ------------------------------------------------------------------------- Years of treatment: 2008, 2009 Management objective: Established population eradication Outcomes: ST/IT = absent LT/IT = present ST/OT = NA LT/OT = NA Base Lake is a 46.5-ha lake on Offutt Air Force Base in eastern Nebraska (41.11466, -95.88681). Zebra mussels were first found in Base Lake in 2006. Monitoring in 2006 and 2007 indicated that the population expanded substantially during that time, and by the fall of 2007, almost all available substrate was entirely covered with attached zebra mussels, often in multiple layers. In areas with suitable substrate, managers estimated that zebra mussels were as densely populated as several thousand per square foot. Veliger tows that year (7/31/2007 and 9/13/2007) found numerous zebra mussel veligers. In 2008, multiple diving surveys were conducted at multiple depths in 61-m transects. The divers reported that zebra mussels were attached to any hard substrate, including concrete, boat docks, inundated and submerged trees and brush, and debris such as aluminum cans, golf balls, and eyeglasses. No zebra mussels were observed within areas that contained only silt and/or sand – which is primarily the substrate of the deeper portions of the lake. On September 17-18, 2008, managers treated the entire quarry with 1 mg/L copper sulfate. That concentration was maintained for 30 hours. Managers monitored water temperature, pH, alkalinity, copper concentrations, and observed fish mortality that occurred during treatment. They assessed adult zebra mussel mortality via settlement plates and samples of adults kept in buckets attached to buoys. Settlement plates had no colonization when they were retrieved 30 d after treatment. All adults in buckets died within 168 h. On October 15, 2008, veliger tows came back negative. The following spring, on April 7, 2009, managers again treated the quarry with 1 mg/L copper sulfate and maintained that concentration for 30 hours. As before, they monitored temperature, pH, alkalinity, and copper concentration, and observed fish mortality that occurred after treatment. They also again used settlement plates. The settlement plates had no colonization when they were retrieved 60 d after treatment. Veliger tows later that year (6/9/2009, 7/8/2009, 8/10/2009) all came back with no veligers. Post-treatment shoreline surveys also found no live zebra mussels. Despite this, by 2014 zebra mussels once again heavily infested the lake. Data sources: Allison Zach (personal communication), URS. Final summary report: zebra mussel eradication project. 2009. --------------------------------------------------------------- Billmeyer Quarry (Lancaster County, Pennsylvania) --------------------------------------------------------------- Year of treatment: 2017 Management objective: Established population eradication Outcomes: ST/IT = absent LT/IT = absent ST/OT = NA LT/OT = NA Billmeyer Quarry is a 12-ha lake in southeast Pennsylvania next to the Susquehanna River (40.07509, -76.65331). Quagga mussels were first found there in 2005, and by 2017, diving surveys confirmed that the mussels were present throughout the entire lake. On September 5, 2017, managers began a 37-day treatment with EarthTec QZ. The product was applied to 50% of the lake’s surface area along the perimeter of the lake. There was no barrier to contain the product, and the EarthTec QZ was allowed to disperse without assistance throughout the entire lake. The initial treatment on Day 1 used 6,245 L of EarthTec QZ, applied at depths of 2 m, 6 m, and 9 m. A bump treatment was performed on Day 7, releasing 4,164 L of EarthTec QZ at depths of 2 m, 6 m, 18 m, 21 m, and 26 m. A third and final treatment was performed on Day 37, releasing 3,123 L of EarthTec QZ at depths between 9-12 m. In addition to copper concentrations, applicators also monitored water temperature, dissolved oxygen, alkalinity, and hardness. Managers observed fish in the lake before, during, and after treatment and noted any mortalities following treatment. Zooplankton were sampled 1-and 2 years post-treatment; species were enumerated at four different sites in the lake, and any additional higher trophic levels found in the samples were noted. A partial draw-down took place following treatment. During the draw-down, managers made visual observations of temporarily exposed areas and found no live adult quagga mussels. Veliger tows did not detect any veligers, and while one eDNA tow performed 2 months post-treatment came back with very low eDNA concentrations, samples collected in the subsequent 4 years were all negative for dreissenid eDNA. As of fall 2021, no live quagga mussels have been found since 2017, suggesting successful eradication. Data sources: David Hammond (personal communication), Hammond, D., and G. Ferris. 2019. “Low doses of Earthtec QZ ionic copper used in effort to eradicate quagga mussels from an entire Pennsylvania lake.” Management of Biological Invasions 10 (3): 500–516. https://doi.org/10.3391/mbi.2019.10.3.07 ------------------------------------------------------ Bone Lake (Washington County, Minnesota) ------------------------------------------------------ Year of treatment: 2019 Management objective: Rapid response eradication Outcomes: ST/IT = absent LT/IT = present ST/OT = present LT/OT = present Bone Lake is an 89-ha lake in east central Minnesota (45.28796, -92.86125). In 2019, six juvenile zebra mussels were found near the public access dock. Given their proximity to the access, they were assumed to be a recent introduction. Over the next few weeks, managers spent more than 70 hours surveying the lake - conducting wading, snorkeling, and diving searches. Three days before treatment began, the team conducted three veliger tows. On June 17, 2019, managers began a 0.23-ha treatment with EarthTec QZ. The treated area surrounded the public access and was contained by a floating barrier. The target dose was 1 mg/L Cu, and actual concentrations ranged from 0.21-1.16 mg/L Cu, with an average of 0.76 mg/L Cu. Treatment concluded on June 26, 2019. Throughout the period, managers monitored water temperature, wind direction, wind speed, and precipitation. Non-target impacts were not monitored. Although the treatment killed juvenile and adult zebra mussels found within the treatment area, the veliger tows taken just prior to treatment later confirmed veligers were already present outside of the treatment area. In 2020, additional veliger tows from throughout the lake came back positive. As of the end of 2021, no juvenile or adult zebra mussels had been found with wading surveys or on settlement plates, although reproduction is assumed from the presence of veligers. Data source: Keegan Lund (personal communication) --------------------------------------------------------- Christmas Lake (Hennepin County, Minnesota) --------------------------------------------------------- Years of treatments: 2014, 2015 Management objective: Rapid response eradication Outcomes: ST/IT = absent LT/IT = present ST/OT = present LT/OT = present Christmas Lake is a 108-ha lake in east central Minnesota (44.89716, -93.54341). Zebra mussels were first found near the public boat access in 2014 during routine aquatic invasive species early detection surveys. Following that initial discovery, managers conducted wading, snorkeling, and diving searches, as well as multiple veliger tows. On September 8, 2014, managers treated a 15x18-m area, enclosed by a barrier curtain, around the public boat access. The treatment used Zequanox at a concentration of 100 mg/L, and managers monitored turbidity, water temperature, and dissolved oxygen. During treatment, project managers used control and treatment bioassay aquaria to monitor zebra mussel survival. Treated bioassay aquaria achieved 100% mortality by Day 11, and no mortality was observed in control aquaria. After the treatment, managers conducted snorkeling and diving searches outside the treatment area to determine if they had treated the extent of the population. On September 19, 2014, 26 zebra mussels were found outside of the treatment area. Beginning on October 4, 2014, managers treated a 0.30-ha area around the public boat access with EarthTec QZ. This time, there was no barrier, and the product was applied at a concentration of 1 mg/L Cu. Copper concentrations decreased from 1 mg/L Cu to less than 0.5 mg/L Cu within eight hours, prompting the installation of a floating barrier around that new larger treatment zone. With the barrier, copper concentrations continued to drop below 0.5 mg/L Cu within 96 h of application. Managers adjusted the application frequency and began treating every 2-4 d to maintain higher copper concentrations. However, on the tenth day of treatment, ice formed on the lake surface, prematurely ending the treatment. During treatment, managers tracked zebra mussel mortality among individuals held in aquaria treated with the same concentration of EarthTec QZ. On December 19, 2014, managers returned to the 0.30-ha treatment area. By then, the barriers were frozen into place. That day, they treated the site with 1,610.17 lbs/acre potassium chloride (KCl), injecting the product under the lake’s ice cover. The following spring, managers returned and conducted diving, wading, and snorkeling surveys. More than 10 zebra mussels were found attached to native mussels, approximately 23-61 m outside of the 0.30-ha treatment site. From June 2-12, 2015, managers applied a second KCl treatment, ranging from 220 - 1,036 lbs/acre, across 0.30-ha surrounding the public boat access. From June 26 - July 8, 2015, they applied a third KCl treatment, ranging from 60.41 - 1,963.56 lbs/acre, across 4.45-ha surrounding the public boat access. Later that year, between August and October 2015, managers inspected boat lifts and collected sampler plates from around the lake. One private boat lift had a single zebra mussel attached, and surveys around that lift found an additional 7 adults nearby. Throughout the lake, eight additional zebra mussels were found. No zebra mussels were found within the treated area. Over the next two years, shoreline transects and veliger tows found that zebra mussels were established throughout the lake. Data sources: Keegan Lund (personal communication), Lund, K., K. Bloodsworth Cattoor, E. Fieldseth, J. Sweet, and M. A. McCartney. 2018. “Zebra mussel (Dreissena polymorpha) eradication efforts in Christmas Lake, Minnesota.” Lake and Reservoir Management 34 (1): 7–20. https://doi.org/10.1080/10402381.2017.1360417 ---------------------------------------------------- Crosley Lake (Kosciusko County, Indiana) ---------------------------------------------------- Year of treatment: 2016 Management objective: Established population eradication Outcomes: ST/IT = absent LT/IT = absent ST/OT = NA LT/OT = NA Crosley Lake is a 1.2-ha man-made lake in northern Indiana (41.31945, -85.71884). In 2016, zebra mussels were found in the lake. On November 1, 3, 7, 11, and 14, 2016, managers applied a cumulative total of 1mg/L Cu in the form of EarthTec QZ across 50% of the surface area of the lake, along the perimeter. Wading surveys conducted around the lake on November 30, 2016, found only dead adult zebra mussels. Treatment is believed to have been successful, and managers are conducting ongoing veliger monitoring. Data source: David Hammond (personal communication) ------------------------------------------------------- Deep Quarry Lake (DuPage County, Illinois) ------------------------------------------------------- Years of treatments: 2012, 2013 Management objective: Research Outcomes: ST/IT = present LT/IT = present ST/OT = present LT/OT = present Deep Quarry Lake is a 16-ha lake in northeastern Illinois (41.93942, -88.17850). In 2009, zebra mussels were found in the lake. In 2012, Southern Illinois University, Marrone Bio Innovations, Inc., and the Forest Preserve District of DuPage County partnered to assess the effectiveness of Zequanox for controlling zebra mussels. On July 18, 2012, the team treated three 24-m2 quadrats with Zequanox. The treatment area was selected based on accessibility, ability to deploy a barrier curtain, and presence of zebra mussels. Zebra mussels were confirmed through wading and snorkeling observations. The target concentration was 150 mg/L and average concentrations were 124, 115, and 93 mg/L in each quadrat. The product was applied to the bottom 0.75 m of the water column with application wands. The research team monitored turbidity, ammonia, total nitrogen, nitrate/nitrite, total phosphorus, chlorophyll-a levels, and at two sites, biological oxygen demand. Following treatment, the team assessed zebra mussel impacts by comparing, between treated and untreated areas, the mortality rates of zebra mussels that were 1) attached to benthic substrates and macrophytes, 2) attached to 1-m sections of tree limbs that were colonized by zebra mussels and placed on the lake bottom, and 3) collected and placed into plastic mesh chambers that were placed on the lake bottom. In 2013, the research team returned to the lake where they conducted horizontal plankton tows to assess veliger population densities and evaluated effects to adult zebra mussels. They treated select locations along two transects (6-7 sites per transect) within a large, enclosed area that included a shoreline. The treatment was targeted to a dose of 150 mg/L and actual concentrations ranged from 33 to 176 mg/L. The product was injected into the bottom 0.3-m of the water column. Near the bottom, the average concentration was 158 mg/L, while near the top the average concentration was 40 mg/L. The research team monitored pH, water temperature, turbidity, conductivity, and dissolved oxygen. Following treatment, they assessed zebra mussel impacts by comparing, between treated and untreated areas, the mortality rates of zebra mussels that were 1) collected as veligers in plankton tows, 2) attached to substrates, and 3) collected and placed into plastic mesh chambers that were placed on the lake bottom. Mean mortality for adult zebra mussels within quadrats in both 2012 and 2013 ranged from 92-98%. Data sources: Greg Whitledge (personal communication), Whitledge, G. W., M. M. Weber, J. DeMartini, J. Oldenburg, D. Roberts, C. Link, S. M. Rackl, et al. 2015. “An evaluation Zequanox® efficacy and application strategies for targeted control of zebra mussels in shallow-water habitats in lakes.” Management of Biological Invasions 6(1): 71-82. http://dx.doi.org/10.3391/mbi.2015.6.1.06 ----------------------------------------------- Lake Erie (Monroe County, Michigan) ----------------------------------------------- Year of treatment: 2014 Management objective: Research Outcomes: ST/IT = present LT/IT = present ST/OT = present LT/OT = present Lake Erie is one of North America’s Great Lakes and has had zebra mussels since at least 1988. In November of 2014, Marrone Bio Innovations conducted a Zequanox treatment in part of Lake Michigan adjacent to Monroe County, Michigan (41.85128, -83.39656). The treatment was a pilot study designed to test targeting Zequanox application to bottom waters. Zequanox was applied at a 15% weight per volume concentration over an area of 31.5 x 25.5 m, contained by a turbidity curtain. Applicators monitored water temperature, turbidity, pH, conductivity, and dissolved oxygen levels. Impacts to zebra mussel were not monitored; the project was designed instead to evaluate the application strategy and technique. Data source: Weber, M. M. Zequanox Application Technique Pilot Study on Lake Erie. Davis, CA, USA: Marrone Bio Innovations, Inc., 2015. ----------------------------------------------- Highland Lake (Lake County, Illinois) ----------------------------------------------- Years of treatments: 2020, 2021 Management objective: Established population eradication Outcomes: ST/IT = present LT/IT = present ST/OT = NA LT/OT = NA Highland Lake is a 41-ha lake in northeastern Illinois (42.36194, -88.06210). Zebra mussels were first found in the lake in 2018, and by 2019, settlement plates confirmed that they were established across the entire lake. In 2020, the lake association conducted veliger tows to establish initial veliger abundance and to collect baseline information on rotifer, copepod, copepod nauplii, daphnia, and ostracod abundance. The treatment was conducted along the lake’s perimeter in a 61 m wide swath that totaled 15.8 ha. There was no barrier to contain the product, and it was allowed to disperse without assistance throughout the entire lake. The first application occurred on July 22, 2020, and consisted of a concentration of 0.4 mg/L Cu within the treatment area. A follow-up treatment on August 7, 2020, added a concentration of 0.26 mg/L Cu, and a final treatment on August 21, 2020, achieved a concentration of 0.26 mg/L Cu. Applicators monitored water temperature and residual copper concentrations. On July 26 and September 27, 2020, the lake association again took veliger tows to determine post-application veliger abundance and to collect further information on rotifer, copepod, copepod nauplii, daphnia, and ostracod abundance. Settlement plates were collected at the end of the year to compare to future years. A second treatment was conducted in 2021 using EarthTec QZ. Treatment was conducted in the same manner as 2020, and zebra mussel settlement was monitored using settlement plates. Data sources: David Hammond (personal communication) John Sonnenberg (personal communication) -------------------------------------------------------------- Lake Independence (Hennepin County, Minnesota) -------------------------------------------------------------- Years of treatments: 2014, 2015 Management objective: Rapid response eradication Outcomes: ST/IT = absent LT/IT = present ST/OT = present LT/OT = present Lake Independence is a 337-ha lake in east central Minnesota (45.02937, -93.65009). On September 25, 2014, the first zebra mussels were found in the lake during a visual inspection around the public water access at Baker Park Preserve. A second inspection the following day found additional zebra mussels attached to a rock underneath the public boat launch dock. On September 29, 2014, the Minnesota Department of Natural Resources, Three Rivers Park District, and Blue Water Sciences conducted additional lake-wide wading surveys. They determined that the population was localized around the public water access and included more than 5,000 adults ranging from 12-19 mm in length. On October 6, 2014, the team initiated a 7-day treatment with EarthTec QZ. They treated 0.2-ha around the boat launch, contained by a barrier. Veliger tows taken during the treatment found no veligers present. The following April 17, 2015, managers conducted a zebra mussel population assessment by wading, snorkeling, and diving throughout the lake. They found 90 live zebra mussels attached to rocks and woody debris beyond the initial treatment area near the public access. This additional finding prompted managers to expand the target area, and from April 28 through May 12, 2015, they treated 0.3-ha around the boat landing with potassium chloride (KCl). KCl concentrations were targeted to 100 mg/L, averaged 77.5 mg/L, and ranged from 39-108 mg/L. Managers monitored potassium concentration and water temperature during the application. During the summer of 2015, settlement plates, diving searches, and snorkeling searches found adult zebra mussels beyond the treatment areas. The zebra mussels were securely attached to debris and native mussels, leading the management team to surmise that they had been attached longer than one season. The team estimated that the mussels had been outside the treatment area (exact treatment boundaries were unknown). Additional searches in 2016, 2017, 2018, and 2019 have continued to find zebra mussels throughout the lake. Data source: Keegan Lund (personal communication) -------------------------------------------------- Lake Irene (Douglas County, Minnesota) -------------------------------------------------- Year of treatments: 2011 Management objective: Rapid response eradication Outcomes: ST/IT = absent LT/IT = present ST/OT = present LT/OT = present Lake Irene is a 259-ha lake in western Minnesota (46.06146, -95.30744). Zebra mussels were first found in the lake on October 7, 2011, when a boat lift was removed. The boat lift was moved from Lake Le Homme Dieu (infested with zebra mussels) to Lake Irene in June of 2011 after reportedly spending a brief time in the lake prior to removal. The company that transported the lift reported that they pressure washed the lift with hot water prior to placing it in Lake Irene. When the lift was taken out of Lake Irene in the fall of 2011, it had many 1-2.5 cm long zebra mussels attached. Following that discovery, local managers conducted a visual inspection on October 8, 2011, for zebra mussels in the area where the boat lift had been in the water. They found 4-5 zebra mussels on the dock closest to the lift, but no additional zebra mussels along the shoreline. Managers continued searching the area, but murky water and cold temperatures made the search challenging. On October 9, 2011, managers conducted a diving search in the area. They found many zebra mussels (avg. 1 cm long) attached to rocks further out from the shore. Zebra mussels were only found in that area where the boat lift had been located. In October and November of 2011, managers treated a 4-ha area around where the boat lift had been with Cutrine Ultra. The product was applied at a concentration of 1 mg/L. Application occurred three times, each 7 days apart, concluding on November 4, 2011. A portion of the treatment area was enclosed by a floating silt curtain to help maintain treatment concentrations. Early in 2012, veliger tows and diving searches did not find any zebra mussels in the lake. However, in the fall, an adult zebra mussel was found about 1.6 km from the treatment area. It was unknown if the zebra mussel was an independent introduction. In 2013, DNR staff were unable to perform follow-up searches due to limited staff availability. There were no reports of any zebra mussels in the lake. In 2014, diving searches confirmed that zebra mussels were still present and reproducing in the lake. Data source: Keegan Lund (personal communication) --------------------------------------------------- Lake Marion (Dakota County, Minnesota) --------------------------------------------------- Year of treatment: 2017 Management objective: Rapid response eradication Outcomes: ST/IT = present LT/IT = present ST/OT = present LT/OT = present Lake Marion is a 214-ha lake in central Minnesota (44.66512, -93.28189). On September 14, 2017, four zebra mussels were found near the public water access during routine early detection surveys. After that initial find, managers and volunteers came together to determine the extent of the infestation. Together, they spent nearly 25 h wading, snorkeling, and diving. Their search found 14 additional zebra mussels ranging from 7-26 mm in shell length concentrated near the public water access. The public water access site was approved to be a pilot project to attempt to eradicate zebra mussels using EarthTec QZ. Following that approval, managers conducted veliger tows. Tows indicated low densities of veligers inside and outside of the proposed treatment area. Treatment began on October 10, 2017, and ran through October 18, 2017. EarthTec QZ was applied at a concentration of 0.5 mg/L Cu across 2.4 ha surrounding the public water access, enclosed by a barrier curtain. Bump treatments were applied on days 0, 2, and 8. Managers monitored dissolved oxygen, pH, temperature, specific conductance, alkalinity, and hardness. In addition to the work in-lake, a bioassay was conducted by USGS staff in a mobile lab to monitor mortality of zebra mussels. On August 9, 2018, managers conducted veliger tows and snorkel and diving surveys. No live or dead adult or juvenile zebra mussels were found, but veligers were present in densities ranging from 1-3 veligers per square m of filtered water. Zebra mussels have subsequently been documented on docks throughout the lake. Data source: Keegan Lund (personal communication) Barbour, M. T., J. K. Wise, and J. A. Luoma. A bioassay assessment of a zebra mussel (Dreissena polymorpha) eradication treatment. Reston, VA, USA: U.S. Geological Survey, 2018. https://doi.org/10.3133/ofr20181138 ------------------------------------------------------------------------------ Good Harbor Bay, Lake Michigan (Leelanau County, Michigan) ------------------------------------------------------------------------------ Year of treatment: 2019 Management objective: Research Outcomes ST/IT = present LT/IT = present ST/OT = present LT/OT = present Good Harbor Bay is a bay of Lake Michigan within northern Michigan, adjacent to Leelanau County (44.95570, -85.85534). Quagga mussels were first introduced to Lake Michigan in 1989. In 2019, the Great Lakes Commission and Invasive Mussel Collaborative partnered to test the feasibility and effectiveness of a targeted Zequanox treatment. From August 7 through 13, 2019, managers applied Zequanox to 300 m2 of Good Harbor Bay, using long wands to reach quarantined quadrats covered by a benthic barrier at the bottom of the bay. Within the quadrats, average Zequanox concentrations ranged from 43-168 mg/L. Managers monitored dissolved oxygen, ammonia-nitrogen, temperature, pH, conductivity, turbidity, total suspended solids, carbonaceous oxygen demand (CBOD), total phosphorus, dissolved phosphorus, and benthic dissolved oxygen. Managers measured quagga mussel density and size distribution within small (20 x 20 cm) sections within the treated quadrats, both before and after treatment. Additionally, managers monitored benthic invertebrate density and composition, the bacterial community, benthic algae, and round goby densities. Data source: LimnoTech. Good Harbor Bay dreissenid mussel control demonstration project discharge summary report. Ann Arbor, MI, USA, 2020. ---------------------------------------------------------------- Millbrook Quarry (Prince William County, Virginia) ---------------------------------------------------------------- Year of treatment: 2006 Management objective: Established population eradication Outcomes: ST/IT = absent LT/IT = absent ST/OT = NA LT/OT = NA Millbrook Quarry is a 4.9-ha lake in northeastern Virginia (38.82085, -77.70340). In late August 2002, the first zebra mussel was reported in Millbrook Quarry. On August 31, 2002, individual zebra mussels were collected and sent in for identification, and on September 3, 2002, they were confirmed as zebra mussels. In April 2003, regional partners inspected the quarry and found that multiple year classes of zebra mussels were present from the surface down to depths greater than 80 feet. Between January 31 and February 17, 2006, a total of 174,000 gallons of potassium chloride (KCl) were applied across all of Millbrook Quarry. KCl was applied each morning, and managers worked to maintain an average concentration of 100 mg K/L. Concentrations were measured at different depths and locations and ranged from 98-115 mg/L. Managers confirmed that zebra mussels were controlled in four ways: 1) managers scraped over 1,000 zebra mussels from rocks throughout the quarry and found none alive, 2) divers conducted an underwater search and found no live zebra mussels, 3) extensive underwater video inspections found no live zebra mussels, and 4) managers monitored lethality through 80 cages containing zebra mussels. Each cage contained 100 initially live zebra mussels. Cages were placed in varying locations and at varying depths throughout the quarry and exposed to the treatment. After 31 d, all test zebra mussels were dead. Control zebra mussels, kept in untreated water, all survived. Data sources: Fernald, R. T., and B. T. Watson. 2014. “Eradication of zebra mussels (Dreissena polymorpha) from Millbrook Quarry, Virginia: rapid response in the real world.” In Quagga and Zebra Mussels: Biology Impacts and Control, 195–213. Boca Raton, FL: CRC Press LLC. Virginia Department of Game and Inland Fisheries. Final Environmental Assessment: Millbrook Quarry zebra mussel and quagga mussel eradication. Richmond, VA: 2005. --------------------------------------------------------------------------------- Robinson’s Bay, Lake Minnetonka (Hennepin County, Minnesota) --------------------------------------------------------------------------------- Year of treatment: 2014 Management objective: Research Outcomes: ST/IT = present LT/IT = present ST/OT = present LT/OT = present Lake Minnetonka is a 5,879-ha lake in east central Minnesota (44.91656, -93.56856). Zebra mussels were first found in the lake in 2010, and today are well established in areas across the lake. In September 2014, USGS tested the efficacy of different Zequanox applications. Five treatments were randomly applied to 27 m2 (3 x 9 m) enclosures for eight hours on three separate treatment days. Enclosures were placed in ~1.5 m deep water along the southern shore of Robinson’s Bay in Lake Minnetonka. Treatments included 1) an untreated control, 2) a 50 mg Zequanox active ingredient (AI) per L whole water column treatment, 3) a 50 mg Zequanox AI/L subsurface application treatment, 4) a 100 mg Zequanox AI/L whole water column treatment, and 5) a 100 mg Zequanox AI/L subsurface application treatment. Each enclosure assessed treatment-related impacts to 1) zebra mussel biomass, via multi-plate samplers that held naturally adhered zebra mussels, and 2) mortality, via mesh containment bags that held zebra mussels adhered to perforated aluminum trays. During treatment, the team monitored dissolved oxygen, pH, water temperature, alkalinity, conductivity, hardness, wind speed, wind direction, nitrogen, phosphorus, and total ammonia nitrogen. Results from the sampler plates and containment bags indicated that biomass and survival was significantly less in groups treated with the highest concentration of Zequanox and in groups that received whole water column applications. When results were standardized to the amount of Zequanox applied, the team found that the lower concentrations and subsurface applications were more cost efficient. Data source: Luoma, J. A., and T. J. Severson. Efficacy of spray-dried Pseudomonas fluorescens, strain CL145A (Zequanox®), for controlling zebra mussels (Dreissena polymorpha) within Lake Minnetonka, MN enclosures. La Crosse, WI: U.S. Geological Survey, 2016. --------------------------------------------------------------------------------- St. Alban’s Bay, Lake Minnetonka (Hennepin County, Minnesota) --------------------------------------------------------------------------------- Year of treatment: 2019 Management objective: Suppression (research project on suppression methods) Outcomes: ST/IT = present LT/IT = present ST/OT = present LT/OT = present Lake Minnetonka is a 5,879-ha lake in east central Minnesota (44.91656, -93.56856). Zebra mussels were first found in the lake in 2010, and today are well established in areas across the lake. In 2019, USGS and the University of Minnesota’s Aquatic Invasive Species Research Center (MAISRC) conducted a 10-day low dose exposure treatment to investigate the effectiveness of low concentrations of EarthTec QZ, applied to the surface waters (epilimnion) to suppress zebra mussel veligers. Prior to treatment, the team assessed veliger and adult population densities through veliger tows and diving along transects. On July 22, 2019, the team treated a 67-ha bay with 0.1 mg/L Cu and they applied bump treatments on July 24, 26, 28, and 30 with the goal of maintaining a long-term concentration of 0.06 mg/L Cu. Subsequent analysis found the treatments ranged from 0.071-0.109 mg/L Cu with a daily average concentration of 0.083 mg/L Cu. No barrier was used; the bay was nearly entirely isolated from the rest of the lake. In addition to copper concentrations, the team also monitored water temperature, dissolved oxygen, alkalinity, hardness, potassium, chloride, sodium, magnesium, calcium, sulfate, dissolved organic carbon, conductivity, and pH. They assessed impacts to chlorophyll, fish, benthic invertebrates, a native mussel species, and zooplankton. Following treatment, they assessed zebra mussel populations through veliger tows, settlement plates, mortality to caged mussels, and counts along diving transects. Immediately following treatment, the team observed reduced zebra mussel veliger density, settlement, and percentage of live adults. Over the next two years, the population began to slowly rebound. Data source: Barbour, M. T., A. D Dahlberg, J. A. Luoma, T. J. Severson, J. K. Wise, B. Bennie, D. Hammond, and D. Waller. In review. “Evaluation of low-dose copper molluscicide to suppress zebra mussel (Dreissena polymorpha) veligers and settlement in a natural waterbody.” ---------------------------------------------------------- Lake Minnewashta (Carver County, Minnesota) ---------------------------------------------------------- Years of treatment: 2016, 2017 Management objective: Rapid response eradication Outcomes: ST/IT = absent LT/IT = present (thought to be reintroductions) ST/OT = absent LT/OT = present (thought to be reintroductions) Lake Minnewashta is a 275-ha lake in central Minnesota (44.88179, -93.60873). Zebra mussels were first discovered in the lake on August 18, 2016, during a routine early detection survey involving wading and snorkeling. The zebra mussels were found directly underneath the west dock at the public access in ~0.5 m of water. No zebra mussels were found on settlement plates. The next day, managers searched nine different areas of the lake and found 10 juvenile zebra mussels directly under the dock where they had been found the previous day. Veliger tows taken that day found no veligers present in the water. On August 26, 2016, managers conducted a second follow-up search throughout the lake and found no additional zebra mussels. From September 13-23, 2016, managers applied 0.3-0.5 mg/L Cu of EarthTec QZ to an 11.7 ha bay that includes Lake Minnewashta’s public access. The area was enclosed by two barrier curtains. One barrier stretched across the channel where the bay enters the main lake, and the other enclosed a smaller area around the public access where the infestation occurred. This allowed for a more aggressive treatment approach in the smaller area, while the larger area was considered a buffer space to catch any mussels that might have spread from the launch. EarthTec QZ was applied only above the thermocline (~ 4-5 m depth). Bump treatments occurred on days 1, 3, 6, and 8. Managers monitored dissolved oxygen, water temperature, pH, conductivity, and copper levels. Additionally, they observed impacts to caged native mussels, made observations on impacts to aquatic plants, and observed a limited fish kill that occurred in the smaller concentrated treatment area. Zebra mussel mortality was assessed by monitoring zebra mussels held in cages within the treated area. Caged zebra mussels were collected from nearby Christmas Lake; there were not enough found in Lake Minnewashta to accurately track mortality. On October 28, 2016, managers conducted a survey of docks and lifts removed from the water by residents and found no zebra mussels. The following summer, managers conducted wading, snorkeling, and diving surveys, as well as veliger tows. One adult zebra mussel was found attached to a rock near the dock at the public access in 2.1 m of water, though no zebra mussels were found on the settlement plate placed beneath the dock. The single zebra mussel was thought to have been a new introduction because of its proximity to the boat launch. No veligers were found in any tows. In September, four juvenile zebra mussels were found again beneath the dock at the public access. Because no zebra mussels were detected elsewhere in the lake, and no settlement occurred on the settlement plate, this was again thought to be a new introduction. Veliger tows in October continued to come back negative. From October 18-27, 2017, managers conducted a second EarthTec QZ treatment across 0.4 ha surrounding the public water access. EarthTec QZ was applied at a concentration of 1 mg/L Cu, with a minimum concentration of 0.6 mg/L Cu recorded. Bump treatments occurred every day except day 2. Managers monitored dissolved oxygen, water temperature, pH, and conductivity. Additionally, they observed impacts to aquatic plants and species-specific related mortality in a limited number of fish. Zebra mussel mortality was assessed by monitoring zebra mussels held in cages within the treated area. Caged zebra mussels were collected from nearby Lake Minnetonka. Follow-up monitoring on June 28, 2018, found 1 adult zebra mussel ~30 m from shore at a private water access on the opposite side of the lake, well outside of the treatment areas. No zebra mussels were found at the public access or anywhere else in the lake. The new zebra mussel was again presumed to be a new introduction because of its size and proximity to the private boat launch. Environmental DNA (eDNA) sampling was positive at the private access in June and later in July, but negative both times at the public access where the treatments had occurred. On August 1, 2018, one veliger was found in veliger tows. The following year, no veligers were detected in tows. No adults or juveniles were found during wading, snorkeling, or rake-toss surveys. Water collected for eDNA sampling came back positive for zebra mussel presence for both the private access and the public launch. On September 24, 2019, one adult was found on a dock and lift near the private access. On October 9, 2019, wading, snorkeling, and diving surveys found one adult zebra mussel near the public access, and various adult and juvenile zebra mussels were found near the private access and neighboring properties. Data source: Keegan Lund (personal communication) ------------------------------------------------------------------- Lake Ossawinnamakee (Crow Wing County, Minnesota) ------------------------------------------------------------------- Years of treatments: 2004, 2005 Management objective: Suppression Outcomes: ST/IT = absent LT/IT = present ST/OT = present LT/OT = present Lake Ossawinnamakee is a 288-ha lake in north central Minnesota (46.62871, -94.19705). Zebra mussels were first found there in 2003. In October 2003, managers completed wading and visual searches in shallow areas around the lake and in Pelican Brook (an outlet stream) and did rake tosses to inspect pulled vegetation. They found multiple adults of varying sizes in the lake as well as multiple adults attached to rocks and wood in Pelican Brook. Pelican Brook was of interest because of its connectedness to the Mississippi River. The next summer, managers collected veliger tows from the main lake body and from Muskie Bay (an eastern bay of the lake from which Pelican Brook exits the lake) at multiple time points throughout the summer. Tows came back with varying densities of veligers. They also conducted diving surveys in the lake to determine the level of the lake’s population and found zebra mussels to be widely distributed. Beginning in the second week of June 2004, managers treated 10.5 ha of Lake Ossawinamakee, in Muskie Bay, with Cutrine Ultra. The treatment was applied to the lake surface and targeted veligers with a goal concentration of 0.6 mg/L Cu. Treatment did not use a barrier. The entire bay was re-treated weekly through mid-September 2004. During treatment, managers monitored copper concentrations in Pelican Brook. Additionally, they sampled invertebrates in Pelican Brook and in two untreated reference communities (Pine and Nokasippi Rivers). Areas of Lake Ossawinamakee west of Muskie Bay maintained zebra mussel populations and settlement throughout the treatment. In 2005, managers returned and, in mid-June, initiated a second treatment with Cutrine Ultra in Muskie Bay. There was no barrier, the product was applied to surface waters, and the bay was re-treated weekly. This year, however, the goal concentration was 0.4 mg/L Cu. Again, managers monitored copper concentrations in Pelican Brook. They monitored invertebrates in Pelican Brook and in the same two untreated reference communities (Pine and Nokasippi Rivers). The goal of both the 2004 and 2005 treatments was to prevent the movement of zebra mussels into the Mississippi via Pelican Brook and Pine River. When zebra mussels were independently discovered in a downstream backwater of the Mississippi (Rice Lake), managers stopped treatment in Ossiwinamakee. Although it is likely that these treatments did control zebra mussels and prevent them from spreading down Pelican Brook, the larger goal of preventing spread to the upper Mississippi River was considered no longer applicable (because of the Rice Lake population). Data source: Gary Montz (personal communication) --------------------------------------------------------------------- Richland Chambers Reservoir (Freestone County, Texas) --------------------------------------------------------------------- Year of treatment: 2018 Management objective: Rapid response eradication Outcomes: ST/IT = absent LT/IT = absent ST/OT = unknown LT/OT = unknown Richland Chambers Reservoir is a 16,736.179-ha lake in Freestone County, Texas (31.97986, -96.14214). Zebra mussels were first found in the reservoir in 2017. In 2018, managers used EarthTec QZ to treat a 2-ha bay at the south end of the reservoir’s dam, near a pipeline intake leading to the Calpine Freestone Energy Center. A silt curtain was used as a barrier to help contain the product. The treatment began with an initial dose of 0.36 mg/L Cu and sought to maintain a concentration of 0.2 mg/L Cu for 20-30 days. Bump treatments began two days after the initial application and occurred 2-3 times per week throughout the treatment. Mortality was monitored by adult mussels placed in cages. The treatment succeeded in achieving 100% mortality of the caged mussels. Data source: David Hammond (personal communication) ---------------------------------------------------- Rose Lake (Otter Tail County, Minnesota) ---------------------------------------------------- Year of treatment: 2011 Management objective: Rapid response eradication Outcomes: ST/IT = absent LT/IT = present ST/OT = present LT/OT = present Rose Lake is a 486-ha lake in western Minnesota (46.67737, -95.74326). On September 19, 2011, a boat lift was pulled from the water at a resort with at least 1,000 zebra mussels attached to it, some of which were alive. The boat lift had been purchased from an individual on Lake Lizzie, MN (with a known zebra mussel infestation), and placed into Rose Lake approximately 6-8 weeks prior to the discovery. On September 28, 2011, managers conducted a lake wide search of docks and boat lifts that had been removed from the lake. In total, they searched 48 lifts and 40 docks and found no zebra mussels. They returned to the initial site of infestation and found at least 20 zebra mussels on the dock wheel that had been closest to the boat lift. No other docks or boat lifts in the area had any zebra mussels. Following those equipment searches, managers searched vegetation that had been raked out of the area surrounding where the boat lift had been placed. They found 15-25 more zebra mussels. They did not find any zebra mussels outside of the area where the boat lift had been. A diver mechanically removed more vegetation from the boat lift area to ensure physical removal of as many zebra mussels as possible. On October 6, 13, and 20, 2011, managers applied Cutrine Ultra to 4 ha surrounding the boat lift location. A portion of the treatment area was enclosed by a silt curtain and the product was applied at a concentration of 1 mg/L. During the summer of 2012, veliger tows did not detect any veligers. Divers searched the lake bottom around where the boat lift had been and found no juvenile or adult zebra mussels. In the fall of 2012, three adult zebra mussels were found during dock inspections, all in the same area as the initial discovery. The next fall, on September 26, 2013, managers again searched docks and boat lifts at the resort where the initial zebra mussel had been found. In total, they inspected 26 pieces of equipment and found no juvenile or adult zebra mussels. In September of 2014, managers did diving inspections in the area where the initial zebra mussel had been found. Again, no zebra mussels were detected. In September of 2015, managers performed wading and visual inspections. In total, they inspected 571 objects across 5 locations around Rose Lake, including docks, boat lifts, sticks, and native mussels. No zebra mussels were found. In 2016, an adult zebra mussel was found approximately 3.2 km from the initial location, and it is not known if this zebra mussel came from the initial infestation. Again in 2017, a single zebra mussel was reported less than 1.6 km from the initial infestation site. Then in 2019, approximately 20 zebra mussels were reported at least 2.4 km from the initial infestation site. Today, the lake is considered infested by the MN DNR given its invasion history. Data source: Keegan Lund (personal communication) ------------------------------------------------- Round Lake (Emmet County, Michigan) ------------------------------------------------- Year of treatment: 2017 Management objective: Research Outcomes: ST/IT = present LT/IT = present ST/OT = present LT/OT = present Round Lake is a 135-ha lake in northern Michigan (46.15083, -86.74159). Zebra mussels were first found in the lake in 2011. In 2017, USGS conducted a study in the lake to determine if uncontained benthic applications of Zequanox could be used to manage zebra mussel populations and protect native unionid mussels. On July 27, 2017, a USGS team began treating three 0.3-ha nearshore plots dispersed around the lake. Each treated plot had a paired control plot. One plot was treated on the first day, the second on July 29, and the third on July 31. The team treated the plots with 200 mg/L of Zequanox and guided the product to 0.6 m above the lakebed. They monitored dissolved oxygen, pH, water temperature, specific conductance, turbidity, total hardness, and alkalinity. The team evaluated caged zebra mussel mortality within the treatment plots during exposures, compared the densities of naturally occurring zebra mussels within the treatment plots before and after treatment, and assessed the survival and infestation of native mussels within the treatment plots before and after treatment. They also assessed native mussel growth following treatment, and collaborators monitored benthic macroinvertebrates, periphyton, and conducted native mussel surveys within all plots. Data sources: James Luoma (personal communication) Luoma, J. A., D. L. Waller, T. J. Severson, M. T. Barbour, J. K. Wise, E. G. Lord, L. A. Bartsch, and M. R. Bartsch. Assessment of uncontained Zequanox applications for zebra mussel control in a Midwestern lake. Reston, VA, USA: U.S. Geological Survey, 2019. https://doi.org /10.3133/ofr20191126 ------------------------------------------------------ Ruth Lake (Crow Wing County, Minnesota) ------------------------------------------------------ Year of treatment: 2015 Management objective: Rapid response eradication Outcomes: ST/IT = absent LT/IT = present ST/OT = present LT/OT = present Ruth Lake is a 242-ha lake in north central Minnesota (46.75104, -93.95282). On June 24, 2015, routine veliger tows detected no veligers. On July 11, 2015, an adult zebra mussel was found on the east side of the lake in front of a vacation rental. On July 14, 2015, area managers conducted a visual inspection around the vacation rental and found a second adult approximately 91 m to the south. The next day, they performed veliger tows at nine different locations around the lake and found no veligers. On July 17 and 30, 2015, managers and volunteers conducted additional wading and visual inspections and found no zebra mussels. On August 15, 2015, a lake user reported a third adult zebra mussel, attached to a rock near where the original zebra mussel had been found. On August 24, 2015, two more zebra mussels were found in that area. On September 3 and 14, 2015, managers returned and conducted diving surveys along 2,987 m of shoreline - including around the public access and fishing piers. They found nine adult zebra mussels near the original location. During that time, on September 7, 2015, they performed veliger tows and found no veligers. To address the new infestation, managers elected to conduct a partial-lake treatment with EarthTec QZ. On September 30, 2015, managers performed additional diving surveys within the designated treatment area. There, they found eight zebra mussels. They collected and caged those individuals and monitored their survival during subsequent treatment. On October 6, 2015, managers performed similar diving surveys in an area designated for use as a control site; no zebra mussels were found there. From October 6 through 14, 2015, managers treated a 1.2-ha area in Ruth Lake with a targeted concentration of 1 mg/L Cu in the form of EarthTec QZ. Actual concentrations ranged from 0.15 - 0.98 mg/L Cu. Managers monitored water temperature during treatment and checked the caged zebra mussels daily for mortality. By October 13, 2015, 100% of the caged mussels had died. In September 2016, one adult zebra mussel was discovered in the Ruth Lake. In 2017, veliger tows taken in June and August did not detect any veligers. Settlement plates and snorkeling and diving surveys also conducted that year did not find any zebra mussels. Through continued annual search efforts using multiple methods, in 2019 a single zebra mussel was found outside of the original treatment area. Today, the lake is considered infested by the MN DNR given its invasion history. Data source: Keegan Lund (personal communication) ------------------------------------------------ Valley Lo Lake (Cook County, Illinois) ------------------------------------------------ Year of treatment: 2021 Management objective: Established population eradication Outcomes: ST/IT = absent LT/IT = absent ST/OT = NA LT/OT = NA Valley Lo Lake is an 11-ha lake located in northeast Illinois (42.09276, -87.80272), surrounded by a country club and 30 private homes. Zebra mussels were first reported there in 2018, and by then were already abundant around the entire shoreline. In 2021, managers decided to pursue an eradication effort using EarthTec QZ. On July 26, 2021, the lake was treated with 2,082 L of product, calculated to yield 0.24 mg/L Cu on the basis of the entire lake volume. Product was applied to all shoreline areas at a width sufficient to comprise 50% of the lake’s surface area (approximately shoreline to 36 m from shore). Water conditions measured before and after treatment included temperature, dissolved oxygen, copper, total and dissolved organic carbon, alkalinity, pH, sulfate, chloride, calcium, magnesium, potassium, and sodium. Adult zebra mussel mortality was monitored in 20 cages stocked with live specimens collected from the lake and then positioned at the surface and bottom in 10 locations. Impacts on larval zebra mussels and non-target zooplankton were monitored by plankton tows performed before, during, and up to seven weeks after treatment. Three days post-treatment adult mussel mortality was 100% in the surface cages and 80% in the bottom cages, and visual inspections of the shoreline also reflected complete mortality in shallow depths. By 10 days after treatment, 100% mortality was observed in the remaining cages placed near the lake bottom. Subsequent applications of product had been scheduled but were determined unnecessary because the eradication was deemed complete with the single dose of 0.24 mg/L Cu. Plankton tows yielded a veliger concentration of 126 per liter on the morning of treatment, six per liter one week later, and zero per liter at four weeks post-treatment. A tentative assessment that the treatment resulted in a complete eradication will need to be confirmed by additional plankton tows and eDNA samples in future years. Data source: David Hammond (personal communication) --------------------------------------- Lake Winnipeg (Manitoba) --------------------------------------- Year of treatment: 2019 Management objective: Rapid response eradication Outcomes: ST/IT = absent LT/IT = present ST/OT = absent LT/OT = present Lake Winnipeg is a large lake in southern Manitoba (50.83070, -96.68335). One zebra mussel was found there on October 11, 2013. Over the next few days, more zebra mussels were found on a private dock in the harbor of Boundary Creek Marina/ Winnipeg beach and on several fishing boats in Gimli Harbor. At this time, an individual came forward and shared that they had found five zebra mussels in 2011 on a piece of PVC pipe in shoreline debris in Traverse Bay. The zebra mussels had appeared to be dead when found. Following the 2013 zebra mussel discoveries, managers inspected docks, dry-docked boats, navigational buoys, and shorelines from Gull Harbor to Seymourville along the south side of Lake Winnipeg. Manitoba Hydro staff inspected the Jenpeg Generating Station. In total, 425 zebra mussels were found at four Fisheries and Oceans Canada's (DFO) Small Craft Harbors (Arnes, Gimli, Winnipeg Beach, and Balsam Bay) as well as at a private docking area at Willow Point. A single zebra mussel was later removed from the bottom of each of two swimming piers at Whytewold when the piers were removed. Five zebra mussels were removed from a dry-docked sailboat at Silver Harbour Resort/ Arnes Harbour. Additional zebra mussels were found on a private dock near Willow Point. The following spring, the Province elected to attempt to eradicate zebra mussels in each harbor to prevent further spread into Lake Winnipeg. Each harbor was closed off from the rest of the lake with silt curtains and treated with 100 mg/L potassium chloride (KCl). Treatment began on May 24, 2014, and was completed by June 12, 2014. During treatment, managers monitored potassium concentrations and water temperature. Bioassays were conducted in 52 locations throughout the harbors to monitor treatment effectiveness. Complete mortality was observed in all bioassays on June 12, 2014, and eradication within the treatment areas was inferred to be a success. However, later that summer, zebra mussels were detected in the open water area of the south basin of Lake Winnipeg. Today, the lake is considered completely infested, as is its outflowing river, the Nelson River. Data source: Laureen Janusz (personal communication)