WYDOT to temporarily close I-90 between Acme and Wyola Montana– detours available

Sheridan, Wyo – The Wyoming Department of Transportation (WYDOT) and Montana Department of Transportation (MDT) have rescheduled the closing of Interstate 90 between Acme Wyoming and Wyola Montana to Monday, October 21, 2024, for the aerial spraying of this stretch of the I-90 corridor for noxious weeds. 

The closure will begin at 7:00 a.m. and will open once spraying is complete – an estimated eight hours. The closure is weather dependent, with Tuesday, October 22 as an alternative date if weather aborts the flight.

MDT will close I-90 at the Wyola, MT Exit 544 and detour eastbound traffic to MT451 and WYO345 through Parkman and Ranchester to the Acme Interchange at Exit 14.

WYDOT will close I-90 at the Acme, WY Exit 14, and detour westbound traffic onto WYO 345 through Parkman to Wyola, MT Exit 544.

Motorists should anticipate potential delays of up to fifteen minutes and an additional thirty minutes of travel time due to heavy traffic and reduced speed limits.

All exits along I-90 within the closure area, including all county and private roads, will be closed to traffic.

A twelve-foot width restriction, and 14’9” height restriction for westbound traffic, will be in place.

Interstate 90 has a severe infestation of ventenata and medusahead in the right-of-way, which serves as a seed source for nearby populations and significantly increases the risk of seed spread throughout the state.

Ventenata and medusahead are extremely damaging invasive species that choke out desirable grasses and can significantly decrease land value. Livestock and wildlife will not graze ventenata or medusahead and they can drastically increase wildfire risk. Both invasive grasses were first confirmed in Wyoming in 2016.

Sheridan County Weed and Pest (SCWP) will be applying an herbicide utilizing aerial spraying.  Aerial application has proven to be the most effective method of applying this herbicide. To apply the herbicide, helicopters need to fly at an altitude of 30 feet above ground level and cannot make applications in proximity to live traffic.

Application by ground spraying equipment is less effective due to the precise and uniform dispersal of herbicide required.

MDT will participate and herbicide application will take place on a two-mile section north of the state line.

All total, 840 acres of right of way in Wyoming and 97 acres of right of way in Montana will be treated.

SCWP will use two herbicides containing indaziflam and imazapic. Both herbicides are approved by the EPA for use in areas grazed by livestock with no restrictions on grazing following application.