Writers on the Range: Glen Canyon Dam has created a world of mud

When Glen Canyon Dam blocked the mighty Colorado River in 1966, it began creating a world of mud 100 miles away, writes Dave Marston, publisher of Writers on the Range. The Southwest's San Juan River is a poster child for that event, as its load of heavy sediment settled to the river bottom over the decades. Now, when the San Juan River enters Lake Powell reservoir, its muddy water adds to a mud pancake that's 49 miles long, a mile wide in some places, and as much as 120 feet deep in the final reaches of the San Juan River. Think "mud bergs" and treacherous, ever-changing channels, though wildlife has returned to the lower San Juan River.