Boulder police and fire officials briefly evacuated two or three apartment buildings near 350 Arapahoe Ave. because the Anderson Ditch was flooding, but residents now have been allowed to return home.

Police found the valves for the irrigation ditch and were able to get the flow going, relieving the flooding, officials said.

Residents began calling police around 7:30 p.m., said Boulder police Sgt. Pat Wyton.. The decision was made to evacuate because water was coming over the sides of the ditch and there was a concern that the embankment could break away, he said.

According to police dispatchers, about 20 to 30 people were evacuated.