The US Army Corps of Engineers (USACE) says Tuttle Creek dam near Manhattan, Kansas, can not withstand a high magnitude earthquake.
USACE says it is currently studying three options which include removing the dam at a cost of US$30M; stabilising the soil beneath the dam for US$100M; or replacing or enlarging the dam for US$250M. Although the cost of dam removal appears cheaper, it is not the preferred option as the cost of restoring the river would probably push the cost to be more than the cost of stabilising the dam.
Historically, the Humboldt fault makes the area prone to earthquakes, but it is unlikely the area would experience one large enough to cause significant damage to the dam. Although Manhattan is not on the fault, it is on the Nemaha Ridge next to the fault.
USACE investigations have indicated that if a high magnitude earthquake occurs the loose sand in the dam foundation could liquefy.