Greeley and Fort Collins have stopped using the Poudre as a water source because of the runoff from the High Park and Hewlett Gulch burn areas.

9NEWS took unfiltered samples from the Poudre River, Horsetooth Reservoir, and Cherry Creek to see how they compare.

In order to understand whether the water is bad, we needed a little science lesson from Metro State Associate Professor of Environmental Science Dr. Jason Janke.

"The first thing we're going to look at is the turbidity," Janke said.

Janke takes samples of our water to test them with a turbidity sensor.

"Turbidity is what we can actually see in the water, so it's a measure of the cloudiness or murkiness of the water," he said.

Normal fresh water measures between 0 and 50 turbidity units or, NTU's.

Poudre was well above normal at 65, Horsetooth was at 42, and Cherry Creek and a regular bottle of water were basically clear.

So, turbidity is what we can see, but what about the stuff we can't see?

"Conductivity is a measure of the dissolved substances in water," Janke said. "It could be minerals it could be elements, basically anything that we can't really see."

The Poudre had a high conductivity reading at 220 micro-Siemens per centimeter.

A clean water source, like Horsetooth, measured 76.

Cherry Creek uses a different river system so it's not comparable, but a bottle of water, because of additives, had a higher conductivity than Horsetooth.

The Poudre's turbidity test was the most concerning.

"It needs some recovery time," Janke said. "It doesn't look appealing, but in terms of what we looked at today there's nothing too alarming."

9NEWS also tested for ammonium. That can be high when there's runoff from fertilizers, animal and human urine or feces. Cherry creek was the worst, followed by Poudre, then Horsetooth.

As for when the Poudre river will clean itself up, Dr. Janke says it could be weeks or months for small particles like ash or clay to precipitate out. It all depends on if we get more rain near those burned out areas.

Dr. Janke didn't think there were any hidden concerns in any of the samples.