August 20, 19U1, the river was discharging 1*2 c*f*s. at a point 2\ 

 miles upstream from LaGrande* Gaging station records of the U.S. 

 Geological Survey for a total of 31 years, taken at or near the 

 same point, show discharges ranging from a maximum of 8,880 c.f.s. 

 in March*1932 to a minimum of 3#9 c*f*s* in August, 19l*0. The 

 average discharge for the same period was 3U5 c.f .s. From Island 

 City upstream to the upper end of the valley just above LaGrande, 

 a distance of about h miles, the river loses its sluggish character 

 and the gradient becomes fairly moderate. On August 20, 19 Ul, the 

 river had an average width of only 20 feet in this section and there 

 was a large amount of exposed stream bed, due to the numerous water 

 diversions and the natural low water conditions at this season* 

 Below the lowermost diversion at Island City the river was reduced 

 to a flow of less than 2 c.f.s* There were approximately 80,000 

 square yards of potential spawning area in this section, of which 

 less than 10 percent was considered suitable because of flow condi- 

 tions, and also because of the large amount of silt deposited as 

 a result of the operation of two gravel dredges in the stream bed. 



There are several obstructions and diversions located be- 

 tween Island City and LaGrande. The first of these is a debris 

 jam at Island City, probably impassable to fish at low water stages. 

 Approximately one mile above Island City there is a power diversion 

 dam about 3 feet high which is considered impassable at low water. 

 The diversion at this point amounts to 6 c.f.s., and furnishes power 

 to a flour mill at Island City* There are several small irrigation 

 pumps about 1^ miles above Island City that operate only intermit- 

 tently. Approximately two miles above Island City there is a stone 

 diversion dam 2\ feet high which is a barrier at low water* This 

 dam diverts a maximum flow of about 2$ c.f.s. into the Caviness 

 irrigation ditch. About 350 yards upstream from the Caviness ditch 

 the May Park irrigation ditch withdraws a maximum flow of about 20 

 c.f.s. Approximately three miles above Island City the Nessley 

 Irrigation Ditch withdraws about 6 c.f.s. About four miles above 

 Island City there is an old irrigation ditch, which was not in use 

 at the time of observation. About 2$0 yards farther upstream there 

 is a rock dam 2\ feet high, which is a barrier to fish at low water. 

 On August 20, 19 Ul, this dam was diverting about 20 c.f.s* into the 

 LaGrande irrigation ditch* The ditch also supplies water to a 

 slaughter house and a lumber mill in LaGrande, which necessitates a 

 fairly large, constant diversion. None of the water diversions on the 

 Grande Ronde River is provided with any fish protective devices. 

 This has undoubtedly contributed to the present depleted condition of 

 the runs of migratory fish* 



37 



