The US military says its troops have killed 33 insurgents in a joint operation with Iraqi troops 80km (50 miles) north of Baghdad.
It said several hundred US and Iraqi soldiers took part in the operation on Monday to reopen the water supply to the town of Khalis.
Residents say al-Qaeda fighters have a strong presence in the area.
Insurgents cut water supplies to Khalis several days ago by shovelling earth into an irrigation canal.
The US military said a joint assault force of US and Iraqi troops - which landed by helicopter - killed 13 insurgents. It said fire from attack aircraft killed 20 others.
The statement did not say whether any US or Iraqi soldiers were killed.
Elsewhere in Iraq, hundreds of thousands of Shia Muslims are attending a big religious festival in Karbala.
A pilgrim is checked by an Iraqi soldier in the holy city of Karbala
Shias gather in the city each year to mark the birthday of the Imam Mahdi in the Ninth Century.
Tight security is in place because Sunni insurgents often launch attacks on Shia festivals.
Four people were killed in clashes with police in Karbala on Monday, when pilgrims became angry at the strict security measures being imposed.
At least one pilgrim were also killed by gunmen taking shots at people driving to the festival.
Another nine people were killed on Monday, when a suicide bomber blew himself up after evening prayers in a mosque in the town of Falluja, west of Baghdad.
The violence came a day after Iraqi Prime Minister Nouri Maliki announced a deal between Iraqi Shia, Sunni and Kurdish politicians.
US President George W Bush welcomed the deal, but warned that much work remained to quell sectarian violence in the country.