The residents say the airstrikes hit today afternoon. They spoke on condition of anonymity out of fears for their safety.
The Islamic State group seized the dam on the Tigris River on August 7 as part of their offensive that's seized large swaths of Iraq.
The residents near the dam say the airstrikes killed militants, but that could not be immediately confirmed.
Iraqi officials said today that survivors of an Islamic State group attack on a northern village told them the militants killed over 80 Yazidi men there, warning that the minority group remains in danger.
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Kocho is in an area held by the Islamic State group where journalists cannot operate.
Islamic State group fighters besieged the village for several days and gave its Yazidi residents a deadline to convert to Islam, Yazidi lawmaker Mahma Khalil said today.
"When the residents refused to do this, the massacre took place," Khalil said.
Halgurd Hekmat, a spokesman for Kurdish security forces, said last night that the militants captured the women and children of Kocho took them to the nearby city of Tal Afar, which is controlled by the Islamic State group.
The United Nations in recent days declared the situation in Iraq a "Level 3 Emergency", a decision that came after some 45,000 members of the Yazidi religious minority were able to escape from a remote desert mountaintop where they had been encircled by Islamic State fighters.
The UN said it would provide increased support to the Yazidis and to 400,000 other Iraqis who have fled since June to the Kurdish province of Dahuk. A total of 1.5 million people have been displaced by the fighting.
It said the converted Boeing KC-135 tanker, called a Rivet Joint, would monitor mobile phone calls and other communication.