Think about it. They provide world class angling for browns, rainbows and cutthroats. Many state and all of the current brown trout world records were caught from these rivers. What makes these rivers different from the hundreds of trout streams scattered acrose our country. The answer's not just special regulations or location, but the physical and chemical characteristics of the reservoirs upstream from the tailwaters.
Water is a wondrous medium.
It makes life possible on our beleaguered planet. It has some unique physical properties. In the liquid state, water as it cools becomes more dense and heavier, until it reaches about 39 degrees, then water starts getting less dense again and lighter as cooling continues. Water molecules slow and ultimately change to a solid called ice. This is why ice floats.