4:00am

Thu September 6, 2012
Wildfire Science

Greeley Water And The Conundrum Of The Contaminated Poudre

It’s been ten years since the Hayman fire, and Denver water officials are still dealing with the fire’s impact to its water supply. In Northern Colorado, water managers are just beginning to assess the damage to their complex system of reservoirs and holding ponds following this summer’s wildfires. 

John McCutchan of Greeley Water says since the High Park Fire, area water managers have had to throw out the book on how they treat water coming from the Poudre River.

Ash and other debris from recent wildfires cake the edge of the Poudre River, a key source of Greeley's drinking water.
Credit USDA/Creative Commons

“It’s new for us to have to be watching the Poudre night and day. We're all faced with the same situation."

Many Northern Colorado water utilities are tied to the Poudre. And McCutchan says Greeley's water rights on the river are too important to "Let go down stream. Especially in a drought period.”

McCutchan is the Superintendent of Greeley's Bellevue Water Treatment Plant which filters water from the Poudre River -a key source for Greeley's drinking supply.

What Once Was Pristine Is Now Contaminated

The normally “pristine” Poudre is the cleanest source of water in the country, McCutchan says. But since the recent fires, the river has been running black with ash and other contaminants.  And that has the potential to clog up the Bellevue Plant.

During a typical year, the city of Greeley uses a diversion dam near the mouth of the Poudre to direct water

Greeley Water's Diversion Dam near the mouth of the Poudre River.
Credit Nathan Heffel / KUNC

from the river through a series of large steel pipes. The untreated water travels from the diversion dam to holding ponds. There it stays for a few days while heat from the sun kills bacteria.

At the same time, a small amount of sediment falls to the bottom of the ponds making the river water easier to clean once it's sent to the filtration system.

But runoff from the scorched-black earth around the Poudre has sent large particles of ash along with increased levels of iron and manganese swirling down the river.

If massive amounts of these contaminates were allowed to enter the filtration system, it could render the holding ponds useless because they'd quickly fill up with sludge and sediment. 

To help mitigate any damage and very costly repairs, Greeley has limited its intake of Poudre River water to just 5 percent after the fire compared to an average of 25 percent for this time of year.

Blending Poudre Water A Balancing Act

McCutchan says Greeley water managers simply don’t know what’s going to happen when they have to return to more “normal” levels.

“We’re going to have to balance the pressure to use Poudre water against what the quality of the water is today. We’re just going to have to be on top of it every single day. Some days we’ll be able to use it, some days we may not be able to use it."

In the meantime, much of Greeley’s water supply is coming directly from the dwindling Horsetooth Reservoir thanks to a water 'sharing/exchange' agreement with North Poudre Irrigation Company

Similar to the Poudre, water from the reservoir west of Ft. Collins is flushed into a treatment plant on Boyd Lake in nearby Loveland.

Sam Boone, a Greeley Water project manager, says just like at Bellevue, a heavy duty filtration system is working to keep Greeley’s drinking water clean.

“We add enough chlorine for the residual [contaminates] to take through all the distribution system, as well as a little bit of fluoride. Whether you like that or not -we don’t have a choice. So we do it.”

Once the water is ready for drinking, it's pumped roughly 30 miles uphill by massive 800 horsepower water pumps to Greeley.

800HP water pumps at Greeley Water's Boyd Lake Water Treatment Plant.
Credit Nathan Heffel / KUNC

What Happens When The Boyd Lake Facility Closes?

The Boyd Lake facility is a good backup system. But since its treated water has to be pumped to Greeley, it's more costly to operate vs.taking the gravity fed water from the Poudre River.  

That's why it's only used during the height of irrigation season.  And with the farming season drawing to a close, the plant is on the verge of shutting down for the year.

This means the city of Greeley and John McCutchan are going to have to take a hard look at what’s going to happen when they’re forced to rely more heavily on the contaminated Poudre.

“Everyone has had the same kind of problems. You can remove most of the contaminates, but some of the compounds that bring the taste and odor issues, the smoky flavor, are very difficult to remove.”

The city of Fort Collins has just started blending water from the Poudre back into its supplies. Each water utility knows that things will change depending on rain and the subsequent runoff into the Poudre. They’re also looking ahead to next spring and the annual winter snow melt, and what that runoff will mean for the river and next year’s water supply.