Dear Editor,

Quoting from American Clean Resources Group, Inc.’s recent note (The Mountain-Ear, April 3, 2025, pg. 7), described as clarification of a local-area mining proposal, “Contrary to some claims, Barker Reservoir is rarely used for Boulder’s primary drinking water supply. Our system is specifically designed to protect against any runoff that might flow toward it. In reality, Boulder’s main drinking water source is North Boulder Creek, accessed via the Lakewood Pipeline.”

Clarifying that clarification, Barker Reservoir feeds Boulder’s municipal water supply via a 36-inch diameter aqueduct called the Gravity Line. It runs 24/7 for six months every year, mid-March to mid-September. That water is treated and injected into the city’s drinking-water system at the Betasso plant.

The Gravity Line moves between 6 to 38 cubic feet of water per second (cfs), with a median flow rate of 22 cfs. A cfs is 7.48 gallons per second and there are 86,400 seconds in 24 hours. So, every day for six months of the year the pipeline conveys a median supply of 14 million gallons to Boulder. Every spring and summer, that’s about 2.5 billion total gallons sent to Boulder from Barker. 

Boulder annually treats six billion gallons of drinking water, according to BoulderColorado.gov. Barker’s annual contribution to the city’s system is therefore around 2.5/6 = 40 percent.

Is that “rarely”?

If the proposed mining operation will drop zero pollutants into Barker, why bring up the reservoir’s fractional contribution at all? Aren’t particular fractions of the city’s water supply irrelevant if the pollution will be zero?

Was the fractional aspect emphasized because some non-zero pollution level was countenanced, but could then be (literally) diluted by saying that the reservoir doesn’t contribute any meaningful amount of Boulder’s water?

Ultimately, are we getting an unequivocal, up-front guarantee of zero reservoir pollution, or is some non-zero amount of potential reservoir pollution on the table?

Just asking questions here.

Frank Sanders

Tungsten Valley