Published: Jul 25, 2010 12:47 AM EDT
Updated: Jul 24, 2010 9:47 PM EDT

MANCHESTER, Iowa (AP) - Warning sirens are blowing in the small eastern Iowa town of Hopkinton as water continues to flow through a dam on Lake Delhi.

Torrential rains have been causing the lake to rise in recent days. Floodwaters from the Maquoketa River have eaten a 30-foot-wide gap into the earthen dam. The lake's level has now dropped as much as 45 feet, with water flowing into the area below the dam.
Water was beginning to surround homes in Hopkinton, a town of about 700 people. Emergency officials in Delaware County say it'll likely cause "significant losses of property."
A meteorologist with the National Weather Service says areas below the dam will see an "initial wave from the sudden shot of water" caused by the dam's failure. That will be followed by a secondary crest as the high water above the dam made its way downstream.