The infamous aquatic invasive plant- hydrilla verticilatta- was detected for the first time in rhode island on august 9- 2023 in indian lake

The Rhode Island Department of Environmental Management (RIDEM) was awarded a $143,409 Project Grant from the U.S. Fish and Wildlife Service under the Fish and Aquatic Conservation - Aquatic Invasive Species program (CFDA 15.608). The grant will fund activities to rapidly respond to the recent discovery of the invasive plant Hydrilla verticillata in Indian Lake, Rhode Island. Key project activities include:

• Conducting a thorough plant mapping survey in 2024 to determine the full extent of the Hydrilla infestation
• Applying an initial herbicide treatment using low-dose fluridone to target and control the Hydrilla plants, with ongoing monitoring to measure treatment effectiveness
• Implementing containment measures such as roping off infested areas to restrict motorized boat access and prevent further spread via fragmentation
• Deploying a seasonal boat greeter at the public boat ramp to collect data on boating activity and promote prevention/decontamination practices

The overall goals are to reduce the Hydrilla population, contain it to Indian Lake, and prevent it from spreading to other waterbodies in the region. This project represents Rhode Island's first Early Detection Rapid Response effort targeting a new aquatic invasive plant species and will serve as a model for future management efforts.

A local survey effort showed the plant grew densely in a few locations but was otherwise sparse throughout the lake- indicating a rapid response is needed. DEM is proposing work to control the invasive plant before IT alters precious habitat in the lake and contain IT to avoid its spread within the lake- downstream- or to other waters in the region. If left unmanaged- hydrilla has the potential to change fish and wildlife habitats- and could lead to reduced fishing- recreation (swimming- boating)- local tourism- lakeshore home values- and tax revenues. Proposed activities include thorough plant mapping in 2024 to verify the extent of the infestation. To help containment efforts and avoid further spread of the plants via fragmentation- the largest patches of hydrilla will be roped off using line and floatation to restrict the areas from motorized boats where propellers may disturb the plants. To work toward eradication- ridem proposes an initial herbicide treatment completed by a licensed subcontractor beginning in may 2024. A low-dose concentration of fluridone would be targeted to maintain the concentration for 90 days with multiple applications from july - august to target emerging plants germinating from tubers in the sediment. Post-treatment monitoring at season end will measure the success of the treatments and serve to outline future eradication efforts. To promote containment- a seasonal boat greeter will be assigned to the public boat ramp to elicit information on boating activity. The seasonal technician will analyze activity outputs from boat ramp interactions- and process data to help track boat traffic patterns. The technician will report out on the number of interactions with boaters- boat traffic timing- frequency- etc. To best target future outreach efforts. Deliverables include annual reports from the herbicide application contractor summarizing treatment activities (bathymetric map- dosing calculations- maps of the treatment areas- maps of pre- and post-treatment hydrilla distributions etc.). Outcomes include reduction of the hydrilla plant population in indian lake and dramatically reduced tuber bank- containment of plant populations to the lake- and suppression of hydrilla spreading to other lakes via boat traffic. The spread prevention activities and boater education outcomes will directly restrict transport of hydrilla out of indian lake but will also affect changes in boater behavior to increase boat hygiene practices at other boat ramps throughout the state. The proposed project will be the first early detection rapid response (edrr) effort by the state of rhode island that includes addressing a new invasive plant with herbicides as well as spread prevention activities and IT will serve as a model for planning future edrr responses. The outcomes of this proposed project will benefit native fish- wildlife- and plants in the lake and watershed- as their habitat is preserved- and threats are reduced. Specifically- activities will help preserve 268 acres of historic spawning grounds for river herring in indian lake. The treatment activities will also maintain areas to be used by recreational boaters- anglers- swimmers- and paddlers who will continue to recreate- with reduced risk of spreading the plant within in the lake (and to other waterbodies). Other beneficiaries include community residents- associations- as well as state and municipal officials who will learn about hydrilla management- including spread prevention- early detection- and rapid management. The grant will afford local officials adequate time to identify more resources and prepare a long-term management plan for treatment at indian lake as needed until the population is securely contained and eventually eradicated.