334 



HYDROGRAPHY. 



Baker's Bay is the usual anchorage of vessels, but it is by no 

 means well sheltered. During the winter months it is much exposed 

 to the southeast winds. 



The New or Clatsop Channel leads directly from the bar to Point 

 Adams. Changes in both these channels have taken place since 

 the surveys of the Exploring Expedition. 



The alteration in the Old Channel is thought to be caused by the 

 wreck of the Peacock ; in the Clatsop Channel, by the great deposit 

 of sand round the wreck of the Shark, and from the failure of the 

 usual spring freshets, which causes the sands to be deposited in the 

 channels, instead of being swept farther to seaward ; and in many 

 cases a slight obstruction causes the water to flow off and make a new 

 outlet through the sandy spit. 



I have carefully compared the chart of the mouth of the Columbia, 

 by the Exploring Expedition, with that of the South Channel, by 

 Lieut. McArthur, of the Coast Survey. The changes have apparently 

 occurred from the causes that I have adverted to ; and, although there 

 is much greater facilities for passing in and out of the Columbia, by the 

 establishment of beacons and marks, and the organization of regular 

 pilots, still these have not obviated, though they have much lessened, 

 the difficulties and dangers which nature has placed upon it, and which 

 all the art of man will not be able to remove. 



In the Clatsop Channel, the water having been diverted, has cut 

 through the South Sandspit, which extends from Point Adams to the 

 west : this makes the entrance less difficult. The sea is smoother, and 

 the channel shielded somewhat from the ocean, by the head of the 

 South Spit. 



To improve and afford facilities for entering the Columbia, Govern- 

 ment have erected a lighthouse on Cape Disappointment, which 

 affords the best direction to the navigator, and permits him to run 

 boldly for the land ; and a blockhouse, on the Middle Sand Island, with 

 a staff 85 feet above high water mark, with a white flag, which can 

 be distinguished plainly 12 miles at sea ; thereby obviating often- 

 times great delays and detention by adverse winds. The blockhouse 

 staff on with the highest peak westward of Chinook Hill, and Point 

 Adams open with Pillar Hill tree, are the ranges for 12 fathoms. 

 With the usual wind, this south channel can be used at all times, 

 and may be easily passed through either with a fair or head wind. 

 The depth of water on the bar is 16 feet at half-flood, making 20 feet 

 at high water ; it deepens to 5 fathoms inside the point of the Spit, 



