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2 c;;JJ708 ANNUAL RUNOFF IN THE UNITED STATES Runoff for the year was in the median range for nearly three-quarters of the United States. The areas of deficient runoff totaled l:ess than in any ather year since 1936 and were mostly in the central half of northern United States. In the Southwest excessive runoff covered the largest area since 1952~ and there was no deficient runoff. ANNUAL RUNOFF IN CANADA Runoff appeared to be slightly less than in 1957. ex. cept in eastern Quebec and the Maritime Provinces where it was excessive and a year ago it was mostly deficient. British Colurnbia.-Runoff for the year ranged from about median to excessive. but it was deficient at each key gaging station at least one month during the year. In Columbia and Fraser Rivers runoff was mostly excessive during the winter and spring and deficient during the summer. Alberta.-Well above median runoff persisted throughout the year; only in April, when snowmelt at high elevations was delayed. and in September~ was it significantly below median. Manltoba.-Runoff was well above median to excessive the first half of the year and below median to deficient the second half. Ontario.-In the first half of the year. above median ru-noff predominated but in the second half runoff was mostly deficient, particularly in southern Ontario; at the key station Saugeen River at Port Elgin runoff was deficient March to September and record low for the month in May, June, and July. Quebec.-Runoff in the east was excessive most of the year, and in other parts of the Province it ranged from deficient to excessive and averaged about median. Maritime Provinces.-Except for October when it was deficient~ runoff was about median to excessive throughout the year. ANNUAL RUNOFF OF MAJOR CONTINENTAL RIVERS Mississippi River, which at Vicksburg. Miss., drains about 40 percent of the United States, had an average flow of 663,200 cfs, 118 percent of median. The mini- mum discharge was 230,000 cfs Oct. 17, 1957. The maximum discharge of the year occurred May 16 at 1 190 000 ds well below the median peak discharge. Runoff for A;gust, however, was 853,000 cfs the highest of record for that month. Mean discharge of Missouri River at Hermann, Mo., was 73,590 cfs. 105 percent of median and the highest since 1952. Maximum discharge was 339,000 ds July 23 and the minimum daily discharge was 16,000 ds Feb. 18. Mean discharge of Ohio River at Metropolis, Ill., was 338,000 cfs~ 135 percent of median and the highest 'i since 1951. The peak discharge was 788,000 ds May 18; the minimum daily discharge was 77,700 ds Oct. 14, 1957. From the above it will be noted that Ohio River, which drains only 18 percent of Mississippi River basin above Vicksburg. contributed 51 percent of the total f1ow.~ whereas Missouri River, which drains 46 percent of the area, contributed only 11 percent of the total flow. The annual flow of St. Lawrence River below Lake Ontario averaged 212,000 cfs, 98 percent of median and the lowest since about 1940. Runoff of Columbia River near The Dalles, Oreg., which drains 237,000 sq miles of the Northwest, aver- aged 181,400 ds after making adjustments for changes in storage in 8 major power reservoirs. This is 109 percent of median for the standard period 1921-45. Peak discharge was 593.000 ds May 31, much less than in the two previous years. Minimum daily discharge was 83,000 cfs Dec. 18. Runoff of Fraser River at Hope, B. C., (drainage area 74,200 sq miles excluding basin of Nechako River above Vanderhoof) was 89,600 ds, 110 percent of median. The maximum daily flow was 324,000 ds May 29 and the minimum daily flow was 23,100 ds Feb. 17. Flow of Colorado River near Grand Canyon, Ariz., which drains 137,800 sq miles of Rocky Mountain and southern intermountain region, averaged 20,040 ds (a total of 14,510,000 acre-ft) which was 108 percent of median. The maximum daily discharge of 106,800 ds occu.rred in Jut1e and the minimum daily discharge of 4,370 ds occurred in August. Elevation of Great Salt Lake at end of year was 4,195.5 ft, 0.5 ft lower than last year and 3.1 ft below the average. FLOODS The most outstanding floods of the year were prob- ably those that occurred in Iowa in May and July, in Texas in February and September. and in Louisiana and Arkansas in late April and early May. The more noteworthy floods during the year occurred as follows: October November Texas North Carolina, Tennessee, Kentucky. Missouri Texas Texas, California, Idaho Alabama, Missouri Maine, Georgia, Arkansas, Louisiana, Texas, California Texas, Arkansas, Louisiana, Mississippi, Puerto Rico Ohio, Indiana, Iowa, Texas New York, Pennsylvania, Illinois, Iowa, Missouri, Kansas, NebraSka Delaware, Maryland, Missouri, Utah Iowa, Louisiana, Texas January February March April May June July August September