Less than 10% of the Eel River watershed is above the Potter Valley Project and on average, less than 3% of the flow of the entire Eel River is diverted through the Potter Valley Project annually. The average total annual flow of the Eel River, measured at the USGS gage at Scotia, is over 5,000,000 acre feet. Prior to the FERC Final Order, the average diversion through the Potter Valley Project was 160,000 acre feet per year. Since the Final Order was put into place, the average diversion, for the past five years, through the Potter Valley Project, has been 90,000 acre feet. In 2009 the diversion flow was only 60,031 acre feet. We have been criticized for continually saying that, on average, 3% of the total flow of the Eel River is diverted through the Potter Valley Project. Criticized, or not, this is the truth. Perhaps we should say that 97% of the entire flow of the Eel River is NOT diverted through the Potter Valley Project. When the Friends of the Eel River say 98% of the Eel River is diverted through the Potter Valley Project it is simply a lie.
The Eel River watershed includes several large tributary rivers. For comparison it is useful to look at the square miles in each of these tributaries. The Middle Fork watershed is 758 square miles. The North Fork watershed is 286 square miles. The South Fork watershed is 689 square miles. The lower Eel River, which includes the Van Duzen watershed and the estuary, is 1,530 square miles. The upper Eel River watershed from Outlet Creek up to, and including, the watershed above Lake Pillsbury is 708 square miles. The entire Eel River watershed is 3,971 square miles. The water shed above Lake Pillsbury that has been lost to salmon and steelhead is 289 square miles (reference to table of comparative sq.miles/acres etc.)
Take a minute to look at a map of the entire Eel River drainage and it will quickly become clear that it is physically impossible to divert water from the main tributaries of the Eel River, all of which lie downstream of the Potter Valley Project, back up the rivers, through the tunnel, and into Potter Valley.