Dust from unpaved roads is a common seasonal concern in Missoula County. This information sheet provides you with an overview of the dust issue in Missoula County and describes for you the available options for addressing road dust issues in your community.

The best and longest lasting way to prevent dust emissions from roads is to pave the road. Current Missoula City-County regulations require all new roads and most driveways in the Air Stagnation Zone* be paved and require reasonable precautions be taken to control fugitive particulate emissions from any source or activity.

Implementing these rules, along with rules regulating industry, outdoor burning and residential wood stoves, has resulted in a real success story. Since 1987 we’ve successfully reduced our annual and 24-hour average levels of particulate matter (PM10) below federal standards. However, with more than 500 miles of unpaved roads in the County, dust continues to be a localized problem, particularly for people who live on unpaved roads with heavy traffic. Additionally, with our rapidly growing population and traffic volumes, we must continue to be vigilant in reducing road dust emissions to protect health and meet air quality standards in the future.


Why Doesn't the County Pave or Treat All Roads?

The Public Works Department estimates that paving costs $100,000 per mile, which means paving all unpaved County Roads would cost approximately $50 million. Since 1995 more than $4 million dollars of Federal Congestion, Mitigation and Air Quality Funds (CMAQ) have been used for paving within the City’s Air Stagnation Zone. Dust abatement costs an estimated $4,000 per mile, which would require a total of $2 million annually to treat all unpaved roads. The total road budget from tax dollars is approximately $1.3 million.

The County continues to look for means to prevent or reduce dust from unpaved roads. Options include increasing the Public Works Department’s share of the county tax dollars, creating Rural Special Improvement Districts and applying for grants when available.


Options for Addressing Road Dust

1. Create an RSID for Paving

Rural Special Improvement Districts (RSID) can be created to provide funding for improvements and maintenance of infrastructure, such as streets. The funds are generated by all the affected property owners. For citizens to create a Rural Special Improvement District (RSID), at least 60% of the affected property owners must sign a petition indicating their preliminary support. Once the petition is presented to the County Commissioners, a public hearing will be held. The RSID can only be created if less than 50% of the owners in the area protest. For more information on forming an RSID contact Jesse Sattley at 258-4816.

2. Create an RSID for Dust Abatement

This is similar to an RSID for paving, but the funds are used for annual dust abatement instead.

3. Hire a Private Firm for Dust Control

A third option is to hire a private firm to apply dust suppressant to the road on a one time or annual basis. The money can be collected through private agreements with affected property owners. This can be done on a voluntary basis or through a Homeowner’s Association. On roads the County maintains, a permit is required through the Public Works Department and only approved suppressants are allowed. Through this permitting system the County does road preparation work before the dust suppressant is applied to maximize the dust abatement benefits. For more information on the dust suppressant permitting system contact Public Works at 258-4753.

4. Contact the Western Federal Lands Highway Division

If an unpaved road accesses federal land then the Western Federal Lands Highway Division may be interested in the project to provide safe and adequate transportation access to and through federally owned lands. For more information contact them at (360) 619-7700.

5. Traffic Control Options

A road surface’s silt and moisture content greatly influence dust emissions. Traffic factors, such as vehicle speed, weight and number of wheels, can also influence dust emissions from unpaved roads. Modifying these factors can influence emissions. State statute requires that an engineering study and “speed limit warrant test” be conducted before a speed limit can be changed. If you believe a speed limit change is warranted on a County road you should put the concern in writing to the Public Works Director, 6089 Training Drive, Missoula 59808.

Public Works can produce “Slow Down Dust Hazard” signs as budgets allow. These signs are considered advisory, however, and are not enforceable. Contact Public Works at 258-4753 if interested.

Weight restrictions and truck routes can only be established by resolution of the County Commissioners.