26 



BULLETIN 1017, U. S. DEPARTMENT OF AGRICULTURE. 



ages for the whole watershed area, because observations were recorded 

 at but two or three stations. In 1885 the number of stations was in- 

 creased to seven and these were distributed quite widely over the water- 

 shed ; so the averages shown in Table 6 for the period subsequent 

 to 1885 are considered more reliable than those for the earlier years. 



Table 7. 



-Maximum, mean, and minimum annual precipitation for subdivisions 

 of the watershed {see fig. 5) for period 1892 to 1919. 



Watershed. 



Maximum. 



Mean. 



Minimum. 



Subdivision. 



Area 

 (square 

 miles). 



Year. 



Depth 



(inches). 



Volume 



(bil- 

 lions of 

 cubic 

 feet). 



Depth 

 (inches). 



Volume 



(bil- 

 lions of 

 cubic 

 feet). 



Year. 



Depth 



(inches). 



Volume 



(bil- 

 lions of 

 cubic 

 feet). 



1 



4,225 

 2,210 

 9,815 

 4,185 

 5,320 

 6,275 

 3,865 



6,435 

 }25,755 



J35, 895 



1916 

 1906 

 1905 

 1896 

 1896 

 1896 

 1904 



1916 

 / 1916 

 \ 1896 

 / 1896 

 \ 1916 



35.2 

 32.5 

 27.7 

 22.2 

 31.6 

 24.5 

 25.1 



34.2 

 27.8 

 27.2 

 26.5 

 25.72 



345.3 

 166.6 

 632.3 

 215.8 

 391.1 

 356. 6 

 225.6 



511.9 



1,661.2 

 1,628.3 

 2, 209. 8 

 2, 144. 8 



24.2 

 21.8 

 21.3 



17.3 

 24.0 

 19.0 

 17.7 



23.4 

 } 21.7 



I 20.8 



238.3 

 111.5 



485.5 

 168.4 

 296.9 

 276.1 

 158.9 



349.8 

 1,300.6 



1,735.6 



1910 

 1910 

 1910 

 1917 

 1917 

 1917 

 1897 



1910 

 1910 



1910 



13.6 

 13.1 



133.3 



2 



67.2 



3 



11. 4 260. 9. 



4 



11.8 

 12.2 

 12.1 

 10.3 



13.4 

 12.2 



12.3 



114.6 



5 



151.1 



6 



176.1 



7 



92.6 



1 and 2 above Fargo 

 and Moor head 



1 to 5 above Grand 

 Forks. 



1 to 7 above interna- 

 tional boundary. 



200.5 

 730.9 



1,029.5 



Figure 6 shows the amount and distribution of the annual pre- 

 cipitation for 1896, which is the year of greatest precipitation from 

 1885 to 1919, inclusive. Table 7 shows the maximum, mean, and 

 minimum annual precipitation for the seven subdivisions of the 

 watershed shown in figure 5, also like quantities for the watersheds 

 above Fargo, above Grand Forks, and for the entire area south of the 

 international boundary. 



The maximum precipitation over sub-areas 4, 5, and 6 occurred in 

 1896, the year in which the precipitation was maximum over the 

 whole watershed. In 1916 occurred the maximum on sub-area 1, on 

 subareas 1 and 2 combined (south of Fargo and Moorhead), and on 

 the watershed above Grand Forks which comprises sub-areas 1 to 5, 

 On subarea 2 maximum precipitation occurred in 1906; on No. 3, in 

 1905 : and on No. 7, in 1904. The precipitation on large portions of 

 the watershed during the first six months of 1916, and during the last 

 six months of 1909, was considerably above normal and caused ex- 

 cessive run-off. Figure 7 indicates the total precipitation for these 

 half-year periods. This combination year was used later in com- 

 puting run-off. The total, however, does not exceed the 1896 precipi- 

 tation (fig. 6) except on the small area south of Red Lake which was 

 covered by the storm of July 20-22, 1909. 



The distribution of the mean annual precipitation for the entire 

 watershed is indicated on figure 8. This map Avas prepared by 



