Ash and unanchored soil left from the wildfire that last summer scarred nearly 8,800 acres in west Carson City is flowing down the hillsides with the onrush of this spring's snowmelt, clogging a municipal water-treatment plant and limiting what can be pumped into the water system.
Last spring, the Quill Treatment Plant at the bottom of Kings Canyon treated about 3 million to 3.2 million gallons a day. This year, even though water is far more plentiful, only about 2 million gallons a day make it through.
"We have a lot more water coming down than we did last year, but we just have to let it go," Public Works Director Tom Hoffert said last month. Since then, temperatures have warmed and the runoff has increased, as has muck in the water, it seems.
The amount of loose soil public works officials have noticed in recent days suggests the water will remain murky throughout the summer, Hoffert said.
The sluggish pace of treatment is an effect of the Waterfall fire, which decimated vegetation that normally binds the soil and limits erosion. Added to the loose dirt is a layer of fine ash. While the soil clogs the plant's filters, forcing workers to stop treatment and clean the equipment, ash passes right through, so some water has to go through the cleansing process repeatedly.
"(Soil and ash) are both there in larger quantities than we've ever seen," Hoffert said.
The difference in how much of the surface water is treated for drinking is being made up with extra water pumped from Carson City's wells, Hoffert said. The city is also mixing relatively clean water from Marlette Lake with the dirty runoff before treatment, so the plant can run more efficiently.
The city uses some of the snow melt making its way through the canyons to recharge the water table. For that water, the ground it sinks into is a natural filter. But the city isn't able to take advantage of the big runoff because it can only handle so much. Most of the water is making its way into the Carson River.
"We're not able to hold the quantity that's coming," Hoffert said.
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