One lane of Highway 37 near Novato was reopened Wednesday, a day after all lanes were closed due to flooding.

The eastbound fast lane was opened around 12 p.m. but the slow lane and both westbound lanes remained closed with no estimated time of opening, according to California Highway Patrol.

The heavily used highway is a major route connecting four counties and last month it was closed or partially closed for nearly two weeks. Drivers were being diverted around the swamped lanes to Atherton Avenue, which Novato police have said creates traffic problems in the city.

The closure was expected to last for some days.