Develop a public information campaign to educate the public, specifically recreational water users, on what is hydrilla, how to identify it, and the threat it poses to the Great Lakes.

This recommendation focuses on public education through development of hydrilla-specific targeted outreach and educational materials, drawing upon existing regional and national program materials, and using existing venues to distribute the materials. Examples include distributing materials at public and private marinas and botanical gardens, organizing lake management and angler association membership mailings and events, developing state aquatic nuisance species programs, and conducting workshops implemented by Partnerships for Regional Invasive Species Management (PRISMs).

Outreach and educational materials should include the following content to be most effective:

• Information on how to identify the plant and how to distinguish it from native plants. The Hydrilla Hunt! ID sheet and ID card are examples of identification materials.
• An overview of hydrilla’s potential impacts if it successfully establishes in the Great Lakes and the importance of diligence with respect to early detection efforts.

Post signage at all access points and implement watercraft inspections at areas of high traffic or at highest use boat ramps within priority public watercourses.

Signage, watercraft inspections, wash stations, and nuisance species disposal stations should be provided with priority given to already infested waters, waters with high boater activity, and waters in proximity to existing infestations. These activities are the most critical in the five high risk Great Lakes watersheds (Southeastern Lake Ontario, St. Clair-Detroit, Western Lake Erie, Southern Lake Erie, and Southwestern Lake Erie). Inspection consists of visually inspecting all areas of boating and recreational equipment (e.g., boats, trailers, motors, livewells, anchors, snorkeling and scuba gear, and paddles) that come into contact with or hold water; removing visible plants, animals and mud; and draining water from all compartments/containers.

An example of an aquatic invasive species (AIS) watercraft education program is the Clean Boats Crew: Guidelines for the Illinois and Indiana Aquatic Invasive Species Volunteer Outreach Program. The manual for this program provides information on how volunteers can organize an AIS watercraft education program, including how to conduct an inspection and a sample script for how to approach recreational users.

For coastal wetland restoration projects within the littoral zones of the Great Lakes, include specific requirements for post-construction monitoring of invasive species, including hydrilla, in project plans and specifications.

Some Great Lakes states, such as Ohio, are focused on coastal wetland restoration to improve water quality by reducing nutrient and sediment loading to Lake Erie and incorporating beneficial use of dredge material to enhance coastal wetland and fisheries habitat. Projects that incorporate fill material should confirm the absence of hydrilla and other AIS from source areas prior to selecting and using fill for aquatic habitat restoration. Additionally, these projects should include specific requirements for post-construction monitoring of AIS, including hydrilla, in all project plans and specifications.

Visual monitoring should prioritize boat ramps/launches and inlets in waterbodies without existing infestations, popular recreational waterbodies and embayment’s with marinas, and waters with depths less than 25 feet.

Inland waterbodies are expected to be more vulnerable to a hydrilla infestation than the Great Lakes proper because they are less turbulent, shallower, and warmer. However, early detection efforts should include nearshore, littoral zone habitats of the Great Lakes watersheds at the highest risk (Southeastern Lake Ontario, St. Clair-Detroit, Western Lake Erie, Southern Lake Erie, and Southwestern Lake Erie).

Develop a specific process for people to report sightings/presence of hydrilla, including agency verification.

For example, EDDMapS provides real-time tracking of invasive species locations and an online tool to report sightings.

Focus response efforts on use of a contact herbicide.

Contact herbicides control hydrilla relatively quickly by damaging the part of the plant that comes in direct contact with the herbicide.

Advocate that state agencies develop a streamlined process that facilitates rapid response upon detection.

Successful rapid response will require close coordination with regulatory agencies and a willingness on the part of regulators to streamline permitting processes, where feasible. Laws and permitting, specifically with respect to application of herbicides, need to provide a path to rapid treatment of new infestations. Existing permitting processes in many states have review and public notification timeframes that hamper the ability to treat hydrilla quickly. Thus, there is a need for a streamlined permitting process. Such a “rapid response” permit should be considered by state agencies for treatments of areas under 3 acres to provide leeway for managers to quickly address new infestations.

Long-term Sustained Control

Eradication is a multi-year effort and requires a long-term commitment. Since successful eradication programs often require more than five years of treatment, it is important to obtain support from agencies and project proponents, as well as a sustained funding source.

Herbicide application is the most effective means of hydrilla management in the Great Lakes. Grass carp, which have been implemented at a much lower frequency in small water bodies, are used in concert with herbicides to manage lower-level infestations. The U.S. Army Engineer Research and Development Center is currently researching potential biocontrol agents for monoecious hydrilla, but no such agents are currently available. Mechanical controls are not a preferred management option unless the infestation is limited to a small patch of hydrilla that can be isolated with a curtain. Mechanical controls can be costly, labor-intensive, and result in extensive spread of plant fragments.

Hydrilla can be found in a variety of systems, from lakes and reservoirs to flowing streams. Identification of the most effective treatment plan for each site is a case-by-case exercise. The following is general guidance:

Refer to the Case Studies page for examples of management in various systems.

Apply contact herbicides at the maximum label rates, along with limited public access in those areas.

Use benthic mats (i.e., burlap barriers) on very small patches of hydrilla in shallow, low-velocity water.

Use limnocorrals (impermeable enclosures) to isolate hydrilla beds for direct application of herbicide.