Trap Club Flood Mitigation Construction Update

Coordination with Rossiter occurring as start of school nears


August 22, 2019

Helena – The Lewis and Clark County Trap Club Flood Mitigation project began earlier this month. The original goal was to have the work in front of Rossiter done prior to school starting. While the project is moving forward, the work in front of the school is taking longer than anticipated.

The project contractor, Bullock Construction, is actively working with Rossiter School to reduce disruptions to the school to the extent possible, including conducting work outside the drop-off and pickup times for the duration of work along Sierra Road. The bus loop will remain functioning throughout the project as well.

“We understand that construction projects can be inconvenient and disruptive to normal routines,” said Lewis and Clark County Engineer Dan Karlin. “We hope that people can be patient because the benefits of this flood mitigation project will make a big difference during flooding. We are working with the contractor to get it done as expeditiously with as few disruptions as possible.”

The construction end date is scheduled for December 26, although it is not anticipated it will take that long.


The Trap Club project is designed to protect Rossiter School and move surface floodwaters more efficiently through the area. In the 2018 flood, approximately 80 cubic feet per second (CFS) flowed through this area. This project is designed with a capacity of 400 CFS. The project will include the installation of 14 culverts along McHugh and Sierra Road to Montana Ave, construction of a diversion and turnout into the Trap Club pit, and lowering and widening of roadside ditches along Sierra Road between North Montana and Interstate 15.