UPDATE: May 21, 2020 5:00pm
Reservoir Elevation: 1320.20 feet
Storage: 69,254 acre-feet out of 71,534 acre-feet (97% of total capacity)
Inflow: 1,690 cubic feet per second (cfs) - falling
Outflow: 1,400 cfs - will remain steady overnight and into tomorrow
With the unexpected 3+ inches of heavy precipitation observed yesterday in the McKay Creek watershed, flow releases (outflows) from McKay Dam are going to remain at 1400 cfs overnight and into tomorrow.
The current objective is to retain the receding inflows this afternoon and then regain the flood control space of the reservoir over the next several days. Minor flooding in yards adjacent to McKay Creek has been observed per spotter reports.
Releases over the weekend will start decreasing as the McKay Reservoir levels return back to the normal capacity level of the reservoir.
Dry weather is forecasted over the next several days.
Note: 3.1 inches of unexpected heavy rainfall occurred yesterday at the Pilot Rock gage. The previous record, going back to 1981, was 2.1 inches.
Reclamation is coordinating with Umatilla County Emergency Management and City of Pendleton Officials on operational releases.
Hydrologic conditions will be continually evaluated through the next several days to assure water full deliveries this summer, and any releases downstream will be minimized.
Another status update can be expected tomorrow.
Other Important notes:
As a reference, the City of Pendleton reported no encroachment of water against homes at 1700 cfs when flows receded during the April 2019 High Flow Event.
For those who are curious how cubic feet per second (cfs) and acre-feet compare, a gain of 1 cubic foot per second (cfs) in a day (e.g. 1 cfs inflow and 0 cfs outflow) equals 1.98 (or ~2) acre-feet of storage.