Budget-stressed MDOT experiments with chemical alternatives to mowing

Martin Luther King Jr. Boulevard in Lansing has seen experimental spraying by the Michigan Department of Transportation to limit the growth of grass during the summer. (Photo by Todd A. Heywood/Michigan Messenger)

LANSING — Facing shortfalls in the budget for summer road maintenance, the Michigan Department of Transportation is experimenting this year with spraying growth retardant chemicals along state-controlled highways in the hopes of reducing the need to mow roadside vegetation. But the little-known pilot project has raised concerns about potential groundwater contamination and possible health effects.

Scott Wheeler, an MDOT program manager known within the department as the “spray guru” said his department’s goal is to maintain roadside grasses at below 12 inches in height.

While MDOT has long used growth retardant in hard-to-mow areas such as boulevard medians, the department is now experimenting with reducing the need for mowing by spraying a mixture of two or three chemicals — Milestone VM, Escort XP and Plateau — over long stretches of the state and state-maintained federal highways throughout Michigan.

Wheeler said that the entire Michigan span of Interstate 94 has been treated, as well as Interstate 96, and areas in and around Bay City, Lansing and elsewhere.

MDOT spokesman Bill Shrek said that the growth retardants have been applied to “most” MDOT roads in the Lower Peninsula.

“With the three herbicides, our equipment costs, labor, and fringe benefits, our cost for growth suppression is $33.40 per acre,” Wheeler said. “Most of our mowing is done by private contract with a statewide average cost of $35.00 per acre. Our hope is to be able with one application of growth retardant to save or eliminate two mowing cycles. The goal is to only have to mow once per year on most roads.”

Green areas along most of the Lower Peninsula's state-controlled highways have been sprayed with chemicals that inhibit grass from growing, including this stretch of M-99 in Lansing. (Photo by Todd A. Heywood/Michigan Messenger)

According to Wheeler the applications are made between 3-6 a.m. when done in populated areas such as along Martin Luther King Jr. Boulevard in Lansing where the spraying recently raised concerns among residents of the Colonial Village neighborhood adjacent to the highway, also known as M-99.

“I was afraid that my dog could be harmed if he walked in the sprayed areas and then licked his paws,” Colonial Village resident Kathy Miles said in an interview.

According to Wheeler, it is safe for people and animals to enter the sprayed areas as soon as the chemicals have dried, which typically takes place within an hour.

Concerns loom over state’s use of chemicals

But some warn that the new widespread chemical application poses risks to the environment.

John Kepner of Beyond Pesticides, a Washington, D.C.-based group that educated on the risks of pesticides points to studies that show some of these chemicals have the potential to contaminate groundwater.

Escort XP contains the active ingredient metsulfuron-methyl which according to the Washington state Department of Transportation, is “highly mobile in the environment and has the potential to contaminate groundwater.”

Plateau contains the active ingredient imazapic, which, according to Washington state, the half-life of imazapic in soils ranges from 31 to 410 days, with a typical time of 120 days and shows moderate to high mobility in the environment, with a moderate potential to leach through soils and contaminate groundwater.

Milestone contains aminopyralid, Kepner said, which has recently been shown to be persistent therefore could contaminate yards and gardens, which could be a concern for people who live near roads being sprayed.

Kepner emphasized that available safety information only relates to the “active ingredients” in the herbicides.

“Pesticide manufacturers do not have to release names of the ‘inert ingredients,’ which make up 40 percent of Escort and 23.6 percent of Plateau. Despite their name, these ingredients are neither chemically, biologically or toxicologically inert. In general, inert ingredients are minimally tested. However, many are known to state, federal and international agencies to be hazardous to human health,” Kepner said.

“This is stuff that is designed to inhibit or extinguish life so we have a lot of real concerns about its impact on the environment and its impact on our water resources,” said Hugh McDiarmid, spokesman for the Michigan Environmental Council, a statewide coalition of environmental groups. “It sounds like a short-term quick fix solution to something that ought to be addressed in a bigger picture manner.”

Sal Hansen, community forester with The Greening of Detroit, has dealt with the ecology of mowing as part of his organization’s vacant lot reclamation work in the state’s largest city.

“I can understand that they need to reduce the mowing costs,” he said. “But there really is always a concern when you are applying chemicals that they are eventually going to make their way into the groundwater. How are [herbicides] going to break down into elements that don’t have adverse effects, especially in a large-scale application?”

Hansen said that one strategy to reduce the risk of potential groundwater contamination is to let the grass grow tall in areas where it doesn’t present safety problems.

“They might want to consider some of the benefits of having unmowed grass,” Hansen said, noting that grass can help absorb toxins from roadways and reduce storm water runoff.

Hansen said that Michigan might also benefit from following the lead of Cleveland, Ohio, which is now planting “low mow” or “no mow” grasses in areas where it is important to keep the grass short.

Michigan Messenger’s Todd A. Heywood contributed reporting from Lansing