Public Works Announces Niwot Road Median Closure Near Diagonal Highway — Sunshine Canyon Area

Public Works Announces Niwot Road Median Closure Near Diagonal Highway — Sunshine Canyon Area

Boulder County Public Works announces a temporary median closure on Niwot Road near the CO-119 Diagonal Highway intersection for utility infrastructure improvements. The closure will affect left turns from Niwot Road onto the Diagonal Highway for approximately six weeks. A signed detour route will be in place.

The project includes improvements along Flagstaff Road between Boulder and the intersection with Coal Creek Canyon Road. Construction is scheduled to begin in July 2026 with completion expected within 16 months.

Water quality monitoring at 8 stations along Boulder Creek, St. Vrain Creek, and Left Hand Creek showed all parameters within acceptable ranges for 2024. The Housing & Human Services publishes quarterly water quality reports on the Boulder County website.

Background

Wildfire risk mapping conducted by Wildfire Partners shows that 35% of properties in the Boulder area are within the wildland-urban interface. Free home assessments are available through the Wildfire Partners program, with rebates of up to $2,500 for mitigation improvements.

Historical context: Boulder County was established in 1861 and covers 741 square miles of diverse terrain from the Great Plains to the Continental Divide. The county’s population of approximately 330,000 residents is served by 1810 county employees across 47 departments and offices.