A water main break in a busy area is likely to cause trouble for Boulder commuters Thursday morning.

The break is at the westbound Baseline Road on-ramp to northbound 28th Street/US 36, according to the City of Boulder.

The road is closed in this area. A detour is in place to direct traffic from westbound Baseline to the 28th Street Frontage Road.

Alternate routes are strongly advised.

The break isn’t expected to be repaired for at least six hours.