From KRDO.com (Rachael Plath)
The burnt ground left in the wake of the Waldo Canyon Fire has increased the likelihood of flash flooding and mudslides. This threat directly impacted two Colorado Springs reservoirs: the Nichols and the Northfield reservoirs.
“When we have rainstorms, it really churns everything up; brings out that vegetation and debris down into the streams and tributaries. It just makes it a little more challenging to treat,” said Andy Funchess, field operations manager for water systems with Colorado Springs Utilities.
According to Funchess, the area surrounding the two reservoirs was badly burned. The runoff and erosion around the reservoirs was affecting the water’s quality.
Funchess said CSU has the ability to treat the water, but the cost would outweigh the benefit. For this reason, CSU drained the two reservoirs. The empty basins will now help with flood mitigation, as in their empty state, the reservoirs will catch debris and water before it rushes down the mountainside.
From the Colorado Springs Independent (J. Adrian Stanley):
For months now, local leaders have breathlessly awaited [Dave] Rosgen’s Watershed Assessment of River Stability and Sediment Supply (WARSSS) study, a detailed explanation of how water will move off the Waldo Canyon burn scar and, more importantly, what we can do to stop it.
But as the study’s finally presented, it becomes clear that Rosgen can’t save us from the powers of nature.
His plan — thousands of pages long — represents a to-do list that likely will cost tens of millions. It’s currently largely unfunded, and will take years to complete regardless. And then there’s the biggest dose of reality: Even if the region does everything recommended, a five- or 10-year storm will still cause mass destruction and may claim many lives. “The increase in flow is going to be with us,” Rosgen tells the crowd. “It’s not going to change a lot. Flood peaks are a reality for the future.”
What the WARSSS can do is ease our suffering. The restoration work it recommends can hold back well over a million tons of mud in a normal monsoon season, ensuring that a two-year rain event doesn’t take out a neighborhood. Plus, it will help the burn scar heal more quickly.
More Colorado Spring Utilities coverage here.
As a practitioner of fluvial geomorphology, I’ve been looking at some of the devastated areas west of Colorado Springs. The sediment load will slow down as vegetation re-establishes on the mountainside. For the long haul, ground cover is most important. There should be armies of people planting and seeding on the mountain slopes.