Ada County Highway District

News and Press Releases Wednesday, July 21, 2021

ACHD Will Dilute & Discontinue Use of Blue Dying Agent in Winter Operations

The Ada County Highway District maintains 5,236 lane miles of roadways during winter operations. ACHD began tinting the salt with a blue dye in an effort to help the public and crews identify which roads have been treated for winter driving.

The colored salt proved beneficial to crews, helping them to avoid redundancy and reduce waste of both time and materials. It was also helpful to commuters to determine if the roads they were turning onto had recently been salted.

Originally, ACHD used Chromatint in 2015. While the salt was easy to identify, the substance stained roads and sidewalks. The District searched for an alternative and found Liquitint, distributed by the same company and marketed as a non-staining polymetric colorant that could be used in place of the de-icing dyes.

Recently, it came to ACHD's attention that the Liquitint product contains two components that could potentially pose risks to the waterways if used in abundance. Although ACHD's process to dilute the dying agent and annual usage rate fall well below the reportable quantities called out by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), the agency has decided to re-distribute previously tinted salt and discontinue any future orders of the dying agent moving forward in an earnest attempt to mitigate any potential risks.

While some areas of Ada County will still see blue tinted salt, ACHD will no longer be using the mixture on the foothills or in the neighborhoods near the river. The areas that are being treated with the blue salt will likely see a less noticeable color, as the remaining stockpile will be further diluted with undyed salt.

Once ACHD's supply of tinted salt is exhausted, they may re-explore options to dye the salt. Any decisions to move forward with a colored salt will be made in partnership with the Idaho Department of Environmental Quality.


Shandy Lam
Deputy Director of Communications

Rachel Bjornestad
Public Information Officer

Christy Foltz-Ahlrichs
Sr. Communications Specialist

Emma Bowers
Digital Media Coordinator

ACHD Main Line 208-387-6100
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