HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE PORTLAND OR
1025 AM PDT SAT FEB 26 2005
...OREGON WATER SUPPLY OUTLOOK AS OF FEB 26TH 2005...
THE OUTLOOK FOR THE SPRING AND SUMMER IS FOR BELOW NORMAL WATER
SUPPLY IN ALL OREGON RIVER BASINS DUE TO BELOW NORMAL PRECIPITATION
AND VERY LOW SNOWPACK THUS FAR THIS WINTER. WATER SHORTAGES AND
RESTRICTIONS FOR SOME USERS ARE A STRONG POSSIBILITY FOR THE COMING
SPRING AND SUMMER.
IT IS HIGHLY UNLIKELY THAT PRECIPITATION FOR THE REMAINDER OF WINTER
AND SPRING WOULD BE OF AN AMOUNT SUFFICIENT TO GET THE SEASONAL
TOTAL BACK TO NORMAL. HOWEVER...SOME SIGNIFICANT RAINFALL THIS
SPRING WOULD BE VERY BENEFICIAL IN MANY WAYS: INCREASED RESERVOIR
STORAGE...INCREASED STREAMFLOW FOR FISHERIES INTERESTS...REDUCED
IRRIGATION DEMAND...IMPROVED RANGELAND CONDITIONS...AND HIGHER
MOISTURE LEVELS IN OREGON FORESTS.
WHILE ABOVE-NORMAL PRECIPITATION IS WHAT IS NEEDED TO IMPROVE WATER
SUPPLY CONDITIONS...THE MOST LIKELY SCENARIO FOR MARCH THROUGH
MAY IS FOR BELOW-NORMAL PRECIPITATION AND ABOVE-NORMAL
TEMPERATURES...ACCORDING TO THE LATEST SEASONAL OUTLOOKS FROM NOAA'S
CLIMATE PREDICTION CENTER. FOR MORE INFORMATION...VISIT
http://www.cpc.ncep.noaa.gov/products/predictions/90day
DUE TO THE DRY CONDITIONS IN OREGON...THIS PRODUCT WILL BE UPDATED
TWICE MONTHLY THROUGH THE SPRING. THE NEXT UPDATE WILL BE ISSUED BY
MARCH 10TH AND WILL INCLUDE COMPLETE UPDATES OF OBSERVED
SNOWPACK...PRECIPITATION...RESERVOIR CONDITIONS AND FORECASTS.
===================================================================
...SNOWPACK ACROSS OREGON...
MOUNTAIN SNOWPACK AS OF FEBRUARY 25TH WAS MUCH BELOW NORMAL IN ALL
OREGON BASINS. IN THE NORTH OREGON CASCADES AND NORTHEAST OREGON
MOUNTAINS...THE SNOWPACK IS COMPARABLE TO THE RECORD LOWS OF
FEBRUARY 1977. SNOWPACK PERCENT OF NORMAL CONTINUES TO DECLINE IN
ALL BASINS...AND THERE HASN'T BEEN SIGNIFICANT SNOW ACCUMULATION AT
MOST SNOW-REPORTING SITES SINCE THE FIRST OF THE YEAR.
SNOTEL AND SNOW COURSE DATA IS PROVIDED BY THE NATURAL RESOURCES
CONSERVATION SERVICE. THE TABLE BELOW SHOWS THE SNOWPACK PERCENT OF
NORMAL AS OF FEB 25TH.
LOCATION PCT OF NORMAL
...CENTRAL AND EASTERN OREGON...
KLAMATH BASIN 49
LAKE COUNTY/GOOSE LAKE BASINS 81
HARNEY COUNTY BASINS 54
OWYHEE AND MALHEUR BASINS 52
GRANDE RONDE...POWDER...BURNT AND IMNAHA 44
UMATILLA...WALLA WALLA...WILLOW...ROCK... 31
AND LOWER JOHN DAY BASINS
UPPER JOHN DAY BASIN 53
UPPER DESCHUTES AND CROOKED BASINS 49
LOWER DESCHUTES AND HOOD BASINS 23
...WESTERN OREGON...
SANDY BASIN 23
WILLAMETTE BASIN 31
ROGUE AND UMPQUA BASINS 42
===================================================================
...PRECIPITATION ACROSS OREGON...
THE FIRST THREE WEEKS OF FEBRUARY WERE VERY DRY...AND WITH NO
SIGNIFICANT PRECIPITATION IN THE FORECAST FOR THE REMAINDER OF THE
MONTH...IT APPEARS THAT THIS WILL BE ONE OF THE DRIEST FEBRUARYS ON
RECORD FOR MOST LOCATIONS IN OREGON. THIS ONLY EXACERBATES THE DRY
CONDITIONS AND THE POTENTIAL FOR WATER SHORTAGES THIS SPRING AND
SUMMER. SEVERAL REPORTING SITES IN OREGON...INCLUDING PORTLAND AND
EUGENE...HAVE ALREADY BROKEN OR WILL BREAK TO RECORD FOR MOST DAYS
WITHOUT RAIN IN FEBRUARY. WATER YEAR PERCENT OF NORMAL DECLINED IN
ALL OREGON BASINS SINCE THE END OF JANUARY. THE TABLE BELOW SHOWS
PRECIPITATION TOTALS IN TERMS OF PERCENT OF NORMAL FOR THE FIRST
THREE WEEKS OF FEBRUARY...AND THE PERCENT OF NORMAL FOR THE 2005
WATER YEAR THROUGH FEBRUARY 21ST.
BASIN PERCENT OF AVG FOR FEB 1ST-21ST OCT-FEB 21ST
...CENTRAL AND EASTERN OREGON...
KLAMATH (OREGON ONLY) 37 75
LAKE COUNTY/GOOSE LAKE 42 93
HARNEY/MALHEUR BASIN 37 82
OWYHEE/MALHEUR 59 95
GRANDE RONDE/BURNT 48 68
UMATILLA/LOWER JOHN DAY 60 64
UPPER JOHN DAY 61 80
UPPER DESCHUTES/CROOKED 63 77
HOOD/LOWER DESCHUTES 30 52
...WESTERN OREGON...
WILLAMETTE VALLEY 28 53
ROGUE/UMPQUA 30 74
==================================================================
...MAJOR IRRIGATION RESERVOIRS...
AT THE CLOSE OF JANUARY...1,238,000 ACRE-FEET OF WATER WAS STORED
IN 27 MAJOR IRRIGATION RESERVOIRS IN OREGON. THE CURRENT STORAGE
REPRESENTS 66 PERCENT OF AVERAGE...AND IS 38 PERCENT OF THEIR
HOLDING CAPACITY. THE CURRENT STORAGE AS OF FEB 1 IS 121 PERCENT OF
STORAGE FOR THIS SAME TIME LAST YEAR. RESERVOIR DATA IS PROVIDED
COURTESY OF THE NATURAL RESOURCES CONSERVATION SERVICE AND THE CORPS
OF ENGINEERS.
==================================================================
...CURRENT AND FORECAST STREAMFLOW...
OBSERVED STREAMFLOW THUS FAR IN FEBRUARY IS WELL BELOW NORMAL ACROSS
MOST OF OREGON...WITH SEVERAL RIVER GAGES REPORTING NEAR-RECORD LOW
RIVER LEVELS FOR THIS TIME OF YEAR. RIVER LEVELS IN MANY AREAS ARE
COMPARABLE TO WHAT WOULD NORMALLY BE OBSERVED IN JULY OR AUGUST.
FORECAST STREAMFLOW VOLUMES FOR THE SPRING AND SUMMER ARE BELOW
NORMAL FOR ALL OREGON BASINS. THE FORECAST FOR THE COLUMBIA RIVER
AT THE DALLES IS BELOW NORMAL AND REFLECTS CONDITIONS ACROSS THE
COLUMBIA BASIN. THE FORECAST VOLUME FOR THE DALLES AND MOST OREGON
BASINS HAVE DECLINED SIGNIFICANTLY IN RECENT WEEKS AS DRY CONDITIONS
HAVE PERSISTED THROUGH FEBRUARY.
THE FOLLOWING TABLE SUMMARIZES THE FORECASTS FOR SELECTED
RIVERS...UPDATED FEBRUARY 25TH. THESE FORECASTS ARE BASED ON
OBSERVED PRECIPITATION AND SNOWPACK AND ASSUME 70 PERCENT OF NORMAL
PRECIPITATION FOR MARCH AND NORMAL PRECIPITATION THEREAFTER.
FORECASTS FOR THE KLAMATH BASIN ARE PRODUCED BY THE
CALIFORNIA-NEVADA RIVER FORECAST CENTER AND WERE LAST UPDATED
FEBRUARY 15TH.
W A T E R S U P P L Y F O R E C A S T S
...FORECASTS AND AVERAGES ARE IN THOUSANDS OF ACRE-FEET...
...'%' IS PERCENT OF AVERAGE BASED ON 1971 - 2000 NORMALS...
STREAM AND STATION PERIOD FORECAST % AVERAGE
COLUMBIA RIVER
THE DALLES JAN-JUL 71200.0 66 107300.
OWYHEE RIVER
OWYHEE RES INFLOW MAR-JUL 210.0 34 613.
MALHEUR RIVER
NEAR DREWSEY MAR-JUL 44.0 40 110.
N.F. MALHEUR RIVER
BEULAH RES INFLOW MAR-JUL 35.0 43 81.
BURNT RIVER
NEAR HEREFORD MAR-JUL 23.0 45 51.
POWDER RIVER
NEAR SUMPTER MAR-JUL 35.0 50 70.
IMNAHA RIVER
IMNAHA MAR-JUL 174.0 58 301.
GRANDE RONDE RIVER
LA GRANDE MAR-JUL 120.0 48 249.
TROY MAR-JUL 895.0 57 1578.
UMATILLA RIVER
NEAR GIBBON APR-JUL 39.0 53 73.
PENDLETON APR-JUL 72.0 48 149.
S.F. WALLA WALLA RIVER
NEAR MILTON APR-JUL 37.0 70 53.
M.F. JOHN DAY RIVER
RITTER APR-JUL 78.0 49 123.
N.F. JOHN DAY RIVER
NEAR MONUMENT MAR-JUL 270.0 45 597.
JOHN DAY RIVER
SERVICE CREEK MAR-SEP 510.0 44 865.
DESCHUTES RIVER
BENHAM FALLS APR-SEP 370.0 70 528.
CROOKED RIVER
PRINEVILLE RES INFLOW MAR-JUL 89.0 48 184.
OCHOCO CREEK
OCHOCO RES INFLOW MAR-JUL 22.0 61 35.
MCKENZIE RIVER
NEAR VIDA APR-SEP 760.0 63 1300.
S. SANTIAM RIVER
WATERLOO APR-SEP 365.0 62 587.
N. SANTIAM RIVER
MEHAMA APR-SEP 515.0 62 834.
WILLAMETTE RIVER
SALEM APR-SEP 2940.0 61 4804.
CLACKAMAS RIVER
ESTACADA APR-SEP 435.0 58 748.
N. UMPQUA RIVER
LEMOLO LK INFLOW APR-SEP 93.0 62 151.
ROGUE RIVER
RAYGOLD APR-SEP 530.0 60 889.
CHEWAUCAN RIVER
NEAR PAISLEY MAR-JUL 49.0 55 89.
SILVIES RIVER
NEAR BURNS APR-SEP 56.0 57 99.
WILLIAMSON RIVER
BELOW SPRAGUE APR-SEP 240.0 62 385.
SPRAGUE RIVER
NEAR CHILOQUIN APR-SEP 135.0 59 230.
KLAMATH RIVER
UPPER LAKE INFLOW MAR-SEP 310.0 60 515.
THESE FORECASTS ARE SELECTED FROM THOSE PREPARED BY: NATIONAL
WEATHER SERVICE, NATURAL RESOURCE CONSERVATION SERVICE, AND B.C.
HYDRO AND POWER AUTHORITY. FOR VARIOUS PROJECT INFLOWS, THE
FORECASTS HAVE BEEN COORDINATED WITH THE U.S. ARMY CORP OF ENGINEERS
AND THE U.S. BUREAU OF RECLAMATION. FOR FURTHER DETAILS ON THE WATER
SUPPLY FORECAST AND CONTINGENCY FORECASTS BASED ON DIFFERENT
SCENARIOS FOR FUTURE PRECIPITATION...VISIT
http://www.nwrfc.noaa.gov/water_supply/water_supply.cgi
AND
http://www.wrh.noaa.gov/cnrfc/water_supply.php
BRYANT