Ramp Down Rates

Ramping rates on the receding limb of a hydrograph limit the rate at which flow declines to protect fish from unnatural flow changes.  The Klamath River ramp down rates at Iron Gate Dam vary by flow magnitude:

Flow at IGD greater than 3,000 cfs:  Ramp down rates will follow the combined 3-day moving average of net inflows into UKL and accretions between Link River Dam and IGD.  The ramp down rates will be implemented to the extent practicable, based on physical constraints at PacifiCorp facilities and safety of workers and the public. 

Flow at IGD between 1,751 cfs and 3,000 cfs:  Decreases in flow of 300 cfs or less per 24-hour period, and no greater than 125 cfs per 4-hour period.

Flow at IGD less than or equal to 1,750 cfs:  Decreases in flow of 150 cfs or less per 24-hour period, and no more than 50 cfs per 2-hour period.

PacifiCorp’s hydroelectric operations limit the ability to manage changes in releases from Iron Gate Dam at a fine resolution, particularly when flow is greater than 3,000 cfs.  In addition, facility control emergencies may arise that warrant the exceedance of the proposed ramp down rates.  All ramping rates above are targets, and are not intended to be strict maximum ramping rates.  Substantial exceedance of the ramp rates should be infrequent, and should result mostly from facility control limitations or other emergency situations.