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ELMORE COUNTY -- Murky river water could be tied to this summer's fires.

Our reporters and photographers noticed the water looked darker than normal on the South Fork of the Boise River in Elmore County, near Anderson Ranch Dam. Forest officials said this is tied to the Elk Complex Fire that burned through that area this summer.

The Elk Complex burned roughly 73 percent of the land surface as either a hot or a moderate burn. So what that did, in essence, is move vegetation or remove vegetation off the forest floor, really just left just bare soil exposed, said David Olson with the Boise National Forest.

Olson said the recently rainfall event last Thursday show the consequences of the exposed, bare soil.

It is very common to see an increase to flow of sediment, dirt, rocks logs that get into the river or reservoir itself, said Olson. So in this case, we really saw the result of a fairly highly-concentrated amount of rain in a short period of time on a freshly-burned area that created the mass movement of material that we saw over the past couple of days.

Some of what is clouding the water is ash from the fires.

There's definitely some mixture of ash in the flow itself, but not only is there ash, but there's also just dirt that's picked up and rocks that are picked up, Olson said. And typically what happens is you have a small creek that will fill with material over the years, and then when you have these higher flows it just, just through erosion it starts picking up all that material that deposited over the years and it just washes it down and it deposited it at its lowest place.

This can also have an effect on animals living in the water. It can kill fish by limiting the amount of oxygen in the water, and the amount of oxygen they can intake.

Probably the biggest concern, I think, looking long term, is the amount of fine material that's deposited in spawning gravels and the potential effect on being able to spawn and or rear young fry or fish, Olson said.

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