WALLA WALLA DISTRICT MINIMUM OPERATING POOL (MOP)
NOTICE NUMBER: 19188 / 22-17
EFFECTIVE: 04/03/2022 00:01 thru 08/14/2022 23:59 PDT
Beginning 3 April and through 14 August 2022, the lower Snake River reservoirs will operate within the Minimum Operating Pool (MOP) ranges. All Snake River dams, and the McNary Lock and Dam, will spill for fish passage in accordance with the 2022 Fish Operations Plan. The Fish Operations Plan will be posted prior to April 3 on the following website: http://pweb.crohms.org/tmt/documents/fpp/2022/.
Facilities affected: McNary Lock & Dam (Columbia River mile 292); Ice Harbor Lock & Dam (SN River mile 9.7); Lower Monumental Lock & Dam (SN River mile 41.6); Little Goose Lock & Dam (SN River mile 70.3); and variable MOP at Lower Granite Lock & Dam as described below (SN River mile 107.3).
MOP ranges for each Snake River pool are listed below. Elevations are in NGVD 29 datum.
Pool Elevation (in feet)
Ice Harbor, Lake Sacajawea 437-438.5
Lower Monumental, Lake Herbert G. West 537-538.5
Little Goose, Lake Bryan 633-634.5
Lower Granite, Lower Granite Lake 733-737.5 (variable, see below)
The Variable MOP operation at Lower Granite is based on Snake River flows.
INFLOW FOREBAY RANGE
120,000+ CFS 733.0-734.5
80,000-120,000 CFS 734.0-735.5
50,000-80,000 CFS 735.0-736.5
0-50,000 CFS 736.0–737.5
Due to 2019 changes to state water quality standards, the Corps anticipates a higher rate of discharge through the dam spillways compared to previous years, and river navigators may experience strong currents and eddies in the dam tailraces. If navigators believe river conditions inhibit safe navigation to or from a lock, they may request a temporary adjustment to spill using the contact information below. Contact with lock and dam shift operators should be initiated no later than 30 minutes prior to arriving at the lock, as a requested redistribution or reduction of spill may take as long as 30 minutes to attenuate. Additionally, downstream departures may be delayed for the requested spill change to be implemented and take effect.
McNary Operator at (541) 922-2231. Call Sign WUJ41 McNary.
Ice Harbor Operator at (509)-543-3231. Call Sign WUJ42 Ice Harbor.
Lower Monumental Operator at (509) 282-7231. Call Sign WUJ43 Lower Monumental.
Little Goose Operator at (509) 399-2233 x231. Call Sign WUJ44 Little Goose.
Lower Granite Operator at (509) 843-2231. Call Sign WUJ45 Lower Granite.
Navigators are encouraged to contact dam operators and report any unsafe navigation conditions. District staff will evaluate the effects of this year’s operations in conjunction with feedback from river users and coordinate adjustments to spillway gate positioning as appropriate.
For additional information contact the NWW Operations Division at (509) 527-7364.
Paul A. Ocker
Chief, Operations Division
Walla Walla District