The Onondaga County Health Department will apply herbicides to approximately 147 acres of the Seneca River next week to treat water chestnuts in the area.

Parts of the river between Baldwinsville and Three Rivers will be sprayed with two chemicals to rid the area of the invasive plant species from Monday, July 25, to Friday, July 29, weather permitting.

Water chestnuts are an invasive species that compete with native vegetation. The plant’s stems reach to the floor of the body of water, while its leaves float to its surface, forming thick, tangled mats that block light from reaching the bottom, affecting wildlife, and hampering boat travel. Worse, it’s notoriously hard to get rid of.

“The biggest problem is that the plant produces a lot of nuts and seeds, so you not only have to get a good kill, you have to do it for a number of years,” said Russell Nemecek, water quality management program coordinator for the Onondaga County Health Department. “We’ve done pretty well in some spots. In other spots, it’s sort of a problem.”

Nemecek said the health department has used herbicides on the plant for several years. Originally, they used products that went into the water, but they now use chemicals that are applied topically to the plants themselves.

The department will be using Clearcast, the main ingredient of which is imazamox, and Rodeo, or glyphosate (which is also the main ingredient in Roundup). Clearcast is considered harmful if absorbed through the skin, and both are unsafe to inhale. However, Nemecek said neither chemical is likely to harm area residents unless they are standing nearby when the herbicides are sprayed.

“There’s really nothing airborne,” he said. “One of the chemicals, Rodeo, as far as the water goes, [the restrictions are] mostly for drinking water and livestock water. I’m not saying you should, but theoretically, you could go in right away. It’s all applied directly to the plants. I won’t tell you some of it doesn’t get into the water. It’s applied topically to the plants. Use common sense. Don’t be next to it at the time of application. The Clearcast has a different set of limitations. There aren’t any restrictions as far as contact or swimming or fishing. The limitations are more for irrigation, hydroponic crops, that sort of thing.”

The herbicides will be applied to certain areas of the river between Jack’s Reef and Three Rivers Point (see sidebar or visit ongov.net/health/documents/WaterChestnutSprayingMaps.pdf for full maps of the treatment areas). In addition, personnel from the Onondaga County Soil and Water District have already begun hand-pulling water chestnuts in some sections of the river, like near Cooper’s Marina.

“That’s something we’ve wanted to do for some time but haven’t been able to,” Nemecek said.

Nemecek said there are some areas in which it makes more sense to hand-pull the plant than to spray, and vice versa.

“You’d be spraying in areas that have really extensive plant growth. We’re talking several acres. You couldn’t hand-pull this. You’d be out there forever,” he said. “In other areas, the plants are scattered. You always get some popping up after a long time. You can’t spray those, so it’s best to hand-pull. If you get a few around your dock or whatever, we encourage people to do those on their own. But we don’t expect them to yank out half an acre in front of their house. It’s just a matter of how much is out there.”

For more information on the herbicide application, contact the Onondaga County Health Department at 435-3280.

Herbicide application area

According to the Onondaga County Health Department, herbicide will be applied to the following areas of the Seneca River between Monday, July 25, and Friday, July 29:

4Forty-eight acres from approximately three-quarters of a mile southwest of the east entrance of the State Ditch Cut downstream to the vicinity of buoy 375

4Twelve acres from west of Dead Creek, including the south side of Maloney Island, to the Route 690 overpass

4Eight acres from the vicinity west of buoy 346, including the north side of Maloney Island, to the Route 690 overpass

4Five acres from the Route 690 overpass to the vicinity of buoy 332

4Twenty-two acres from the Route 690 overpass to the vicinity of buoy 331 upstream from the Baldwinsville Dam

4Fifteen acres between buoy 294 and the Route 370 overpass

4Three acres downstream of buoy 269

4Twenty-two acres from the vicinity of buoy 266 to the vicinity of buoy 256

4Twelve acres from approximately .4 miles north of the Route 31 bridge to the vicinity downstream of buoy 222