River 21^ miles above the mouth. The stream is about 70 miles long. 

 The lower 5 miles and the upper 15 miles have a moderate gradient and 

 contain some spawning area. The middle 50 miles of this stream meanders 

 through a flat, fertile, cultivated valley, and contains little suitable 

 spawning area. Starting at Cherry Grove, a ^proximately 60 rniles above 

 the mouth, the stream v/as surveyed for a distance of 5 miles. The dis- 

 charge from July through October usually ranges from 10 to 100 c.f.s. 



The Oswego diversion dam, located 4'2 miles above the mouth, is 

 about 5 feet high and is equipped with a fishv/ay. The Osv/ego diversion 

 canal, located 6 miles above the nouth, diverts an average of 69 c.f.s., 

 to Oswego Lake and powerhouse below. The return is discliarged directly 

 into the Willamette » The diversion take-off is not screened. 



Lee Falls ^ located 3 miles above Glierry Grove is 12 feet high and 

 is a total barrier "Co fisho There is little suitable spawning area 

 above the falls . 



A few spring Chinook and silver salmon and steelhead trout enter 

 the streai^i, but the Tualatin has never been an important salmon pro- 

 ducer ' Numerous small tributaries are of no value to migratory fish 

 because of their lack of spa\7ning area. 



25D-(l). Da^json Creek » — (September 22, 1940; Frey and Zimmer.) 

 Snters the Tualatin River approximately 3^ miles above the nouth. The 

 stream is about 5 miles long, and was discharging aViout 4 c.f.s. The 

 stream bed is composed almost entirely of mud and silt, v;ith little or 

 no suitable snavming area„ Uaivson Creek v/as considered to be of no 

 value for the production of salmon. 



25D-(2). ] 3airy Creek . — (September 22, 1940j Frey and Zirnmer.) 

 Enters the Tualatin River approximately 41 miles above the mouth. The 

 stream is about 25 miles long, and tlie discharge was 8 c.f.s. At the 

 town of pfenning, about 15 miles above the nouth, tliere is a 5 foot high 

 dam for a log pond. This dam is provided with a fishvray. The stream 

 contains little suitable spawiing area, and was considered to be of no 

 value to migratory fish. 



25D-(3)- Gales Creek .— (September 16-21, 1940; Yrey and Zimjuer. 

 September 12, 1945; i'arkhurst, Brewington, and Davis.) Enters the 

 TiJalatin River approximately 50 miles above the nouth. The stream is 

 about 30 miles long, of wliich I5 miles were surveyed, starting 2 miles 

 above the mouth. Gales Creek has had 7;'inter floods as high as 3,500 

 Cof.s., and discharges during the summer low water period as lovif as 

 6 c.f.s. The mean flo7/ for the v/ater-year 1944-45 was 162 c.f.s. in 

 the lower section near the tovm of Forest Grove (U.S.G.S. records). 

 T]ie great fluctuation in volu]-.ae has been due largely to major forest 

 fires in the upper voters hed. The gradient is slight to moderate and 

 the water temperature ranged from 53 to 69° F. 



3& 



