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LIEUTENANT HOWISON REPORT ON OREGON, 1846 19

of the tortuous channel not over ten feet deep at low water. The straight channel which Captain Wilkes discovered has be- come obstructed about its eastern entrance, and nothing can be made of it. A channel nearly parallel with it, but to the south- ward, was traced in my boats, and I devoted a day to its ex- amination, and carried through three fathoms at low water; but my buoys bei'ng submerged by the tide, prevented me from testing its availability in the schooner. From Pillow rock the channel is at least three fathoms deep at the dryest season all the way to Fort Vancouver, except a bar of fifteen feet at the lower mouth of the Wilhammette, and another about a mile and a half below the fort. The Wilhammette enters the Co- lumbia from the southward by two mouths, fourteen miles apart; the upper is the only one used, and six miles below Vancouver. Throughout the months of August and Septem- ber, it is impracticable for vessels drawing over ten feet. Both it and the Columbia, during the other months, will easily ac- commodate a vessel to back and fill drawing thirteen feet.

The Columbia is navigable to the Cascades, forty miles above Vancouver; the Wilhammette up to the mouth of the Clackamas river, twenty-one miles above its junction with the Columbia, and three below the falls, where the city of Oregon is located. These rivers reciprocally contribute their waters to one another at different seasons of the year. When the winter sets in, generally with the month of October, and rains are almost incessant, the Wilhammette river receives all the waters which drain from the valley of its name, which imme- diately raise it above the level of the Columbia, into which it flows with a strong current, causing a rise in the latter, and sometimes a ge'ntle reflux of the waters up stream; this con- tinues until March, when the rains cease and the Wilhammette settles to its level. 'Tis then, however, the warm rays of the sun begin to penetrate the more northern and frozen resources of the Columbia ; the mountain snow and ice are soon converted into streams, which simultaneously contribute, along a course of seven or eight hundred miles, to swell this majestic river until,