almost entirely lacking. Three power sites exist on the Wynoochee River, two of which have a possible combined usable storage capacity of 300,000 acre-feet. The potential power at the three sites, with Segulation of the proposed storage would be about 17,000 kilowatts Sor 90 percent of the time. The estimated cost per kilowatt, however, Es $470, which is greatly in excess of the cost now justifiable. 33. Bridges.-There are 18 bridges in the navigable stretch of the iver, details of which are shown in table 1. TABLE 1.-Bridges over Chehalis River 1 Plans approved by War Department. 34. Navigation.-The river is considered navigable to Chehalis, about 76 miles above the mouth of the Hoquiam. Of the tributaries, only the lower 15 miles of the Black River are considered navigable. In the early days, Chehalis River was navigated to 80 or 90 miles above he mouth. Present navigation is limited to the tidal stretch from he mouth to Elma, about 31 miles, although very little commerce is carried above Montesano. The existing project (act of August 30, 1935) for improvement of the river by the Federal Government in the nterest of navigation, provides for suitable bar and entrance channels and for a channel 18 feet deep at mean lower low water and 200 feet vide from Aberdeen to Cosmopolis, and for a channel 16 feet deep at nean lower low water and 150 feet wide from Cosmopolis to Monesano. An 18-foot channel has been dug to Cosmopolis and a 12-foot channel has been dug from Cosmopolis to Montesano; the completion to a 16-foot depth is awaiting the required local cooperation. The extreme tidal range at the mouth is 18.1 feet. The range between nean lower low water and mean higher high water is 9.9 feet. 35. Climate and precipitation. In common with other portions of western Washington the Chehalis Basin enjoys a mild and equable limate. Although the basin compares with New Brunswick and northern Maine in latitude, extreme cold is unknown. The lowest emperature recorded in 41 years at Centralia, in the interior basin, is -16° F., and in 47 years at Aberdeen is 6° F. Maximum tem peratures of 105° have been recorded at both of these stations. The mean annual temperature throughout the valley is about 50°. The growing season (period between killing frosts) is about 209 days. LABLE 36. Rainfall throughout the basin is abundant, but distributed unevenly throughout the year. About 85 percent of the annual pre cipitation occurs during the wet season, from October to April November, December, and January are the months of greatest pr cipitation; July and August are the driest months. Snowfall is normally quite light except at the headwaters of the Wynoochee and Satsop Rivers. Table 2 gives a summary of meteorological data for stations in and near the basin. 19 34 J TABLE 2.-Meteorological data for stations in and near the Chehalis River Basin, compiled from records of the U. S. Weather Bureau to Dec. 31, 1938 Length of record Temperature, 7 Eleva- Aver Mean age Length of annual an- Years Inches Inches 17 (1914-1938) 97.65 41.1 10 (1926-1938) 143.45 12 (1927-1938) 122.16 28 (1906-1938) 137.25 9.9 11.4 Days 209 203 191 164 191 301 38 37. Gaging stations and stream-flow records.-Records of Chehalis River discharges are extremely meager. In October 1928, the United LE 5 States Geological Survey in cooperation with, and using funds pr vided by this Department, established a staff gage on the Chehalis River near the town of Grand Mound. The gage was changed to recording station in October 1934, and has been maintained to the present time. In March and April of 1929, staff gages were estab lished with War Department funds on the Chehalis River near Che halis, on the Skookumchuck River near Centralia, on the Newaukum River near Chehalis, and on the Satsop River near Satsop; the firs three being maintained until September 1931, and the Satsop g (changed to a recording gage in March 1938) maintained until the present time. In October 1939, a staff gage was installed on Chess River near Doty, and the Skookumchuck station reestablished with a recording gage, both with War Department funds. 38. The United States Geological Survey has collected stream-fo records at two stations on the Wynoochee River: One at Oxbow, nest the headwaters of the river, from May 1925 to the present time; and one near Montesano, about 15 miles upstream from the mouth, from February 1923 to September 1930. 39. Of the seven gaging stations only three-one on Chehalis Rive one on Satsop River, and one on Wynoochee River-have records four major flood periods (February 1932, December 1933, January Men... 40. Flo 1973. Ma December Ar 193 about one F 1935, and December 1937). Tables 3 to 5, following, summarize available stream-flow data for those three stations. TABLE 3.-Mean monthly discharge, in second-feet, of Chehalis River near Grand Mound Year ending 1929. 1930. 1931. 1932 1933. 1934. 1935. 1936. 1937. 1938. 1939. 1929. 1930. 1931. 1932 1933. 1934. 1935 1936. 1937 1938. 1939. Mean. TABLE 4.-Mean monthly discharge, Year ending 1925. 31926 1927. 1928 1929. 1930. 1931 1932 1933. 1934 1935. 1936. 1937 1938. 1939. Mean Oct. Nov. Dec. Jan. Mean. 900 405 193 197 1,729 409 885 399 252 242 3, 170 436 295 650 3,620 543 1,100 2, 740 2,800 1, 240 189 229 3, 558 243 6, 787 312 7, 859 4, 251 550 3,366 816 3, 412 6,045 6,234 5, 031 4, 848 3, 114 1,121| 944 377 219 Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Sept. Year 2,300 3,940 4,390 2,038 5, 127 1,577 in second-feet, of Satsop River near Satsop 888 488 1,640 870 1, 187 976 420 2,300 2,490 992 794 830 501 Feb. Mar. Apr. May June July Aug. Sept. Year 1,328 510 600 804 386 550 612 481 425 836 979 537 5291 614 308 644 1, 140 522 992 1,019 832 511 772 283 3,482 276 2,692 413 587 321 422 372 445 293 462 314 329 242 645 317 578 355 351 258 367 253 449 296 TABLE 5.-Mean monthly discharge, in second-feet, of Wynoochee River at Oxbow Year ending 475 764 183 404 758 1,055 919 527 292 327 494 644 472 284 227 250 296 1,250 590 1,770 809 2,130 327 2,432 451 2,415 Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Sept. Year 374 1,687 266 1,653 208 2,320 281 1,580 373 1,979 40. Floods. Floods have occurred in December 1891, in 1892, 1897, 1903, March 1908, November 1909, January 1914, December 1915, December 1917, January 1923, February 1932, December 1933, January 1935, January 1936, and December 1937, or on an average of about one in 3 years. The relative severity of these floods cannot be determined from the existing data, but above the mouth of Satsop River the floods of December 1917 and December 1933 were the most severe. On the Satsop and Wynoochee Rivers the flood of January 1935 was the greatest of record, and at the mouth of the Chehalis the flood of December 1933 was most severe. 41. High tidal stages caused by wind result in inundation of exten sive portions of the cities of Aberdeen, Hoquiam, and Cosmopolis. The following table shows the record of flood tides: 1912__ November 1913. Date 42. Records of daily discharges of Chehalis River near Grand Mound, Satsop River near Satsop, and Wynoochee River at Oxbow, are avail able for the floods of February 1932, December 1933, January 1933, and December 1937. Feb. 25, 1932. Feb. 26, 1932 Feb. 27, 1932. Feb. 28, 1932. Mar. 4, 1932. Mar. 5, 1932. Mar. 6, 1932 Mar. 7, 1932. Dec. 9, 1933 Dec. 10, 1933 Dec. 11, 1933 Dec. 12, 1933 Dec. 17, 1933. Dec. 18, 1933. Dec. 19, 1933. Dec. 20, 1933 Elevation above mean lower low water 15. 0 December 1923. 45. Table 6 shows daily mean discharges at the three gages for the floods of February 1932, December 1933, January 1935, and Decem ber 1937. 43. Of the 2,174-square-mile area drained by the Chehalis River system, 1,308 square miles, or 60 percent, is tributary to the three river gages mentioned in the preceding paragraph. The sum of the 24-hour discharges recorded at these gages for the floods of February 26, 1932; December 21, 1933; January 22, 1935; and December 25, 1937, were, respectively, 53,400 second-feet, 76,400 second-feet, 79,700 second-feet, and 67,900 second-feet. The estimated corresponding 24-hour discharges of Chehalis River at its mouth were 72,000 seconds feet, 104,000 second-feet, 106,000 second-feet, and 90,000 second-feet. 44. A study of the few high-water periods occurring during the 10 years of record indicates that the Satsop and Wynoochee Rivers ord narily reach their flood crest a day or two before the crest occurs on the upper Chehalis River, thus maintaining high stages on the Che halis River below Wynoochee River for a longer period than on any of the tributaries. Chehalis River near Grand 7,150 15, 800 21,800 18.400 7,240 12,700 19.700 16,700 38,800 24,900 9,660 25,800 42,900 36, 100 Discharge in second-Run-off Discharge in second Run-off charge in second- Ru Discharge Dis- Discharge in second- feet per in in second- feet per in 13 in feet per square inches second- square inches mile feet mile TABLE 6.-Flood data square Satsop River at Satsop Wynoochee River at 0 square miles) 15.2 15.8 53.1 122.2 155 Chehalis Black. Satsop Total. Chehalis River near Grand Discharge Discharge in 45,000 44, 300 38,800 23,900 17,800 36, 300 26,800 46,300 35, 800 25, 300 96612-44 square 48.5 47.7 41.8 25.8 19.2 39.3 31.6 29.9 49.9 38.6 27.3 Grays Harbor County. Total-- River 1.80 1.77 1.55 96 71 1.46 1. 18 Satsop River at Satsop 1.11 1.86 1.44 1.02 21, 200 18,000 11,600 7.800 45.900 30.100 32, 800 30. 100 14. 200 13,800 9,470 square 67.3 57.1 36.8 24.8 145.7 95.6 104, 1 95.6 45. 1 43.8 30. 1 Culti vated land 2.50 2.12 1.37 .92 5.42 3.56 3.87 3.56 1.68 1.63 10, 200 6,350 3.440 2,290 16,000 12,000 13,000 11,000 7,000 4.740 1. 12 2,610 Acres 710 Wynoochee River at Oxbow (drainage area, 65 square miles) Discharge in secondfeet 46. Extent and character of flooded area. Following the severe flood of December 1933, a survey of flood damages on western Washington streams was conducted by the State planning council with funds provided by the Washington Emergency Relief Administration. This survey shows approximately 20,000 acres of agricultural land in the Chehalis Basin were inundated by the 1933 flood as follows: 470 360 910 12,390 Area flooded, December 1933 Acres 290 Discharge in second- Run-off mile 156.9 97.7 52.9 160 220 480 35. 2 246. 2 184.6 200.0 169. 2 5,000 107.7 72.9 40. 2 Pasture Raw land land Acres 30 10 210 380 2,230 5.84 3.63 1.97 1.31 9. 16 6.87 7.44 6. 294.01 2.71 1.50 Total Acres 47. In addition to the agricultural area shown in the preceding tabulation, 1,534 acres in Hoquiam, Aberdeen, and Cosmopolis, and an undetermined number of acres of residential and industrial lands, particularly in Centralia and Bucoda, were inundated by the 1933 flood, and a further amount of brush and wastelands not included in the Washington Emergency Relief Administration survey. From outlines of the area inundated by the 1933 flood as sketched by the county engineers of Grays Harbor, Thurston, and Lewis Counties, it is estimated that gross area of about 58,000 acres was inundated, as follows: 15, 390 1,030 640 790 1,770 19, 620 Acres 40, 000 6, 000 12,000 58,000 48. Considering the character of the maps available, this estimate of 58,000 acres is in close agreement with the estimate of 50,000 acres, |