The U.S. will need to spend more than $600 billion over the next 20 years to improve the water infrastructure of several mid-size and large cities with a declining population, according to a report released Monday.

The Government Accountability Office released a report on the water infrastructure needs of cities in the Midwest and Northeast with declining populations, and found that there is going to be a reckoning soon for the country. The report cites an Environmental Protection Agency report that estimates about $655 billion is needed for water and wastewater infrastructure in the next two decades.