BOISE, Idaho (AP) — Americans are using less water, though people in the Northwest individually use more than the national average and Idahoans use more than people in any other state. A study by local, state and federal officials tracking everything from collective sips at the public fountain to irrigating crops to water used to cool nuclear power plants has found that water usage has dropped to levels of at least 40 years ago. "This is the first time we've seen this large a decline nationally," said Molly Maupin, a Boise-based hydrologist with the U.S.