One thousand migrating chinook salmon are currently stalled at the mouth of the Shasta River, drawing close scrutiny by California Department of Fish and Game biologists who are concerned about the possibility of a fish kill.
DFG biologist Mark Pisano reported that the fish have been in the river canyon since Sept. 4.
Pisano said low water levels and high temperatures are factors that could be hindering the migration and such a “bottleneck” has the potential to lead to disease among the population.
DFG crews have been monitoring the stalled school, the majority of which are in a pool approximately one-quarter mile above the fish counting weir at the river’s confluence with the Klamath.
Pisano said the fish counts at the weir, coupled with radio telemetry technology, have allowed monitoring crews to come up with their current estimate of 1,000, as well as their location.
Record low water levels in Shasta and Scott
The Shasta River has experienced record low flows over the course of the last month, prompting concern among environmental groups.
“We’ve been looking at record to near-record low flows for over a month on both the Shasta and the Scott Rivers,” said Scott Harding, executive director of the Klamath Riverkeeper, who is also concerned that these levels, combined with higher water temperatures, could be lethal for fish.
A USGS hydrograph – a device that measures river flow – located near the confluence of the Shasta and Klamath rivers, showed a reading of 23 cfs on Sept. 23, a record low for that date. The historical mean average is 95 cfs. That number has dipped to as low as the 6 cfs over the course of the last month.
Currently, Shasta Valley irrigators are continuing to divert their full adjudicated water rights, with irrigation season ending on Oct. 1.
“We’ve alerted the California Water Board,” said Malena Marvin, science director for the Riverkeeper, expressing her concern that, despite the record low flows and the imperiled salmon, there has been no effort made to curtail water use.
“We hope that by raising attention around this issue, we can put pressure on the water master (to keep a closer eye on water diversion),” continued Marvin. “The conditions are ripe for a fish kill and people are concerned.”
Pisano noted that the current situation, while not ideal, does not preclude disaster. “We had an incident similar to this in ’02,” said Pisano, noting that in that case the fish eventually continued on their way.
• Check for web updates on this story, as well as an in-depth article in next week’s paper.