Why Is the Little Colorado River So Blue?

 by Amanda Podmore, Grand Canyon Director

The Little Colorado River is best known for its milky blue waters that flow into the mainstem Colorado River in the Grand Canyon. These waters carry so much life-giving significance. For millennia, they have provided physical and spiritual sustenance for Indigenous peoples and supported plants, wildlife, communities, and more.

But the Little Colorado River is not always blue. Sometimes it runs as thick and brown as chocolate milk. With a little knowledge of the river’s annual peaks and lows and an eye on the weather gauge, you can predict whether it will be brown or that remarkable turquoise blue. 

So why and when is the Little Colorado River so blue?

The source of its milky blue waters

The Little Colorado River gets its blue color from dissolved calcium carbonate in the water. This mineral is found in chalk, antacids, eggshells, dark green vegetables, rocks, and more. In the Little Colorado River, calcium carbonate forms a type of limestone called travertine that creates white, pillowy deposits along the riverbed. Most of the turquoise-blue water in the Little Colorado River comes from springs 10 to 13 miles upstream of the confluence. Thanks to these groundwater-fed springs, the last 13 miles of the Little Colorado River flow year-round at an average rate of 220 cubic feet per second (cfs) until joining the mighty Colorado River, which has an average flow between 8,000 and 25,000 cfs!

SHANE MCDERMOTT

The Little Colorado River’s year-round flows are important for the region’s largest population of humpback chub. The warm, cloudy waters make excellent habitat for this threatened fish species.

Other colors of the Little Colorado River 

When the Little Colorado River begins its journey from its headwaters in the White Mountains, its waters are not yet blue. The clear mountain stream flows north into the desert lands below, picking up sediment, minerals, and debris along the way. But less than 20 miles from its source, the Little Colorado River dries up. And for the next 300 miles, the river relies on precipitation to send water downstream. Modern-day water use is a major culprit of this dry stretch of the Little Colorado River. Year-round flows return near Blue Spring, 13 miles upstream of the confluence.

During two high runoff periods each year — in the spring from snowmelt and in the late summer from monsoon rains — the Little Colorado River runs red. During these periods, from February to April and July to September, the Little Colorado River may spike to 18,000 cfs. At this runoff level, the water can be so thick and muddy that placing your hand just an inch below the surface of the water makes it invisible to the naked eye.

AMANDA PODMORE

All that sand, dirt, and mud is important to the Grand Canyon and mainstem Colorado River. Sediment from the Little Colorado River forms beaches downstream that create backwater habitat for fish, birds, and insects, provide campsites for river trips, and protect archaeological sites from erosion.

The cultural significance of the Little Colorado River's blue waters

The Little Colorado River’s blue waters have been of deep cultural significance to Native peoples since time immemorial. At least 10 tribes have traditional connections to what Zuni people refer to as “the umbilical cord” of the world. For Hopi people, the Little Colorado River is the home of their emergence story, and its waters, springs, and salt remain important to this day. Adjacent Diné (Navajo) communities, whose land may be affected by proposed dam development, are considering a sacred site designation for the area to prevent development threats like the former Escalade tram proposal.

But to truly understand the importance of the Little Colorado River, I suggest you go directly to the source. Visit the Lifeways of the Little Colorado River collection to hear 11 Native voices share their personal and cultural ties to this life-sustaining river.