The worries have prompted proposals to limit acreage available for leasing.
Officials in Nevada and Arizona have been sending letters to Interior Secretary Ken Salazar expressing concerns about the need to protect Colorado River water quality and quantity.
Others back a Bureau of Land Management proposal to sharply reduce acreage available for possible leasing in Colorado, Wyoming and Utah.
Chris Treese, spokesman for the Colorado River Water Conservation District, says the concerns are overblown.
The Grand Junction Daily Sentinel reported Monday that regulators believe the water supply will be protected and any pollution will be diluted by the time it reaches Las Vegas.
(Copyright 2012 by The Associated Press. All Rights Reserved.)