How significant is the double counting in existing watershed studies?
The volume of water double counted is probably over 600 acre ft. To put this in perspective, this is about twice as much water as needed for the long term development plan. In the San Juan County Surface Water Assessment report Table 2-2 (pg 5) “Average Monthly Discharge Cascade Creek, June 2003 through March 2004” assumes that the Rosario diversion is operating at 100.0% capacity every single day, and none of the water leaks back into the stream. Most of the year, the diversion leaks so bad that all of the water returns to Cascade Creek. This water is counted again downstream by the flow gauging station and added to the total again. A very simple set of tests could quantify this, and make the existing studies more valuable by understanding the real flow, as opposed to an idealistic model that is contradicted by casual observation of the diversion ditch. I look forward to simple, scientific tests being conducted to quantify the return flow.
