The National Weather Service says the Lake Delhi dam in eastern Iowa has failed and several small communities downstream could be severely flooded.
Meteorologist Chris Legro says water has been detected flowing beneath the dam and a complete failure is possible.
Legro says about half of Hopkinton, a city of about 700, could be flooded. He says flooding also is likely later Saturday in Monticello, a city of about 3,600 people.
Here's a little more information from the National Weather Service:
AT 108 PM CDT...THE LAKE DELHI OR HATWICK DAM IN DELAWARE COUNTY IS
AT LEAST 75 PERCENT BREACHED...WITH A 30 FOOT WIDE AND GROWING GAP
IN THE BERM ALONGSIDE THE DAM. WATER IS FALLING 40 TO 45 FEET FROM
THE POOL BEHIND THE DAM TO THE RIVER BELOW.
Anyone in the area needs to move to higher ground, and do not drive through a flooded roadway.