

1936] MAMMALS AND LIFE ZONES OF OREGON 9 



dry up, leaving miles of baked, glistening mud flats. Most of the 

 basin lakes are shallow. The shore lines of some are steadily re- 

 ceding because of the diversion of water for irrigation. Eventually 

 some of these lakes also will be mere playas. Lake Harney has been 

 reduced to that state for a decade. As usual, inland drainage is the 

 result of rainfall that is not sufficient to overflow the valleys and cut 

 out the rims to connect with lower levels. Added to this is an arid 

 climate in which the evaporation over a large surface of standing 

 water more than balances the precipitation over a considerably 

 greater drainage area. 



Malheur Lake, which in 1897 when it was first seen by the writer 

 was an enormous tule swamp overflowing into Harney Lake as it 

 did when Peter Skene Ogden first saw it in 1826, was practically dry 

 in 1931, when buffalo skulls were collected in its baked mud bed. 

 Overutilization of the water of streams naturally flowing into it had 

 ruined the hay and grain ranches around the borders of this great 

 fertile valley, lowered the water table until the valleys became a part 

 of the surrounding desert, and destroyed one of the most important 

 wild-fowl-breeding grounds in the State. 



Eecently these conditions have been corrected by addition of a 

 considerable part of the drainage of the Blitzen River (Donner und 

 Blitzen) to the Lake Malheur Wildlife Refuge, allowing sufficient wa- 

 ter to reach the lake to restore it to a normal level and extent of sur- 

 face and swampy border. The enlarged circle of moist and fertile 

 land restores the ranch values of the valley, and 30 miles of lake and 

 tule swamp restore the spectacular breeding and resting grounds of 

 swans, geese, ducks, pelicans, cranes, egrets, herons, ibises, curlew, 

 and a host of swimming and wading birds and valuable fur bearers. 



Goose Lake and the Klamath Lakes, on the southern border of the 

 State, have cut outlets through the southern rim of their basins, and 

 their waters reach the ocean through Pit and Klamath Rivers. At 

 one time these valleys may well have been a part of the Great Basin, 

 with which they still closely agree in climate, flora, and fauna. 



Lakes of a yet different type many of them large, deep, clear, 

 and cold lie along the higher parts of the Cascade Range in Oregon 

 and serve as reservoirs of snow water that is let down during sum- 

 mer months to thirsty fields below. The best known and most spec- 

 tacular of these, Crater Lake (pi. 6) , half fills its cuplike crater to a 

 depth of 2,000 feet and presents a unique picture of beautiful color 

 and form. Although the lake is without visible outlet, the water 

 remains at a uniform level. It seems not improbable that some of 

 the large streams that burst out below may drain the lake through 

 underground channels in the mountain side. Other lakes owe their 

 origin to lava dams or terminal moraines and generally form the 

 headwaters of important streams. 



Still another set of lakes is that of the immediate coastal strip 

 old embayments or estuaries cut off from the ocean. Not much 

 above the ocean level, they remain as land-locked bodies of fresh 

 water held back by sand bars or dunes. 



Then, too, there are the prehistoric lakes such as once covered a 

 great area in the Columbia River Valley east of the Cascades, the 

 Snake River Valley above the canyon, the greater Malheur Valley, 

 and the northern end of Lake Bonneville in Alvord Valley. Present 



