Downstate Public Ponds to Be Treated for Invasive Aquatic Weed Hydrilla

With inland water temperatures rising and aquatic plants emerging, the Delaware Department of Natural Resources and Environmental Control will be treating certain downstate public ponds for the nuisance aquatic weed hydrilla, starting the week of May 24, 2021. Hydrilla is a non-native, invasive plant that likely entered the state through the aquarium trade. Uncontrolled hydrilla can choke ponds and other waterways, crowding out beneficial plant species and preventing fishing and boating access.

Ponds to be treated this year are Millsboro Pond, Tub Mill Pond and Abbotts Mill Pond near Milford, and Wagamons Pond in Milton. Signs will be posted at the boat ramp of each pond on the day of treatment.

Sonar, an aquatic herbicide containing fluridone, will be used to treat the ponds for hydrilla. Sonar is registered and approved for use by the U.S. Environmental Protection Agency. It has been used in Delaware since the 1980s and has proven to be environmentally-compatible and effective for controlling hydrilla. Sonar does not pose a threat to wildlife, including fish, and there are no restrictions on fishing or consumption of fish after these treatments.

The only restriction is water from the treated ponds should not be used for irrigation for 30 days after the date of treatment. Residents and farmers along and directly downstream of treated ponds should not use the water to irrigate their gardens, yards or agricultural lands during that period to avoid possible damage to their plantings. Landowners with permits to use water from these ponds will be directly notified before treatment.

To prevent the spread of hydrilla and other invasive aquatic vegetation, anglers and boaters are encouraged to remove all hydrilla and other aquatic plants from their boats, trailers and gear before leaving boat ramp areas.

For additional information, contact the DNREC Division of Fish and Wildlife at 302-739-9914.

The Delaware Department of Natural Resources and Environmental Control protects and manages the state’s natural resources, protects public health, provides outdoor recreational opportunities, and educates Delawareans about the environment. The DNREC Division of Fish and Wildlife conserves and manages Delaware’s fish and wildlife and their habitats, and provides fishing, hunting, wildlife viewing and boating access on nearly 65,000 acres of public land. For more information, visit the website and connect with @DelawareDNREC on Facebook, Twitter or LinkedIn.

Media Contacts: Joanna Wilson,; Michael Globetti,