Their dams cause floods, and that gets them in trouble with humans. But in the right place, more water can be a big help.

More flash flooding is expected at many of Utah’s outdoor gems on Friday, and additional flooding is likely again on Saturday, as remnants of Hurricane Priscilla continue to churn through the state.

Seven hikers who entered a narrow desert canyon for a day of canyoneering became trapped when a flash flood filled the chasm with water, killing at least six of them in Zion National Park in southern ...