Yes. The Colorado River travels through a huge area (watershed).  During this journey it naturally erodes a lot of rock and soil which makes the water very turbid.

The Colorado River carries about 100 million tons of soil into Lake Powell every year.  (That's about 30,000 dump trucks!) 

Many rivers, like the Colorado, are naturally turbid.  They move soil downstream which builds new stream banks and islands.  When this happens, the Colorado River is just doing its job.