The Columbia River, once the premier fishery for Chinook salmon, both sport and commercial, has many renowned tributaries that are world-famous meccas for steelhead anglers. Because the Columbia is now in its lowest water cycle and is also the most dammed river on earth, most of the anadromous fisheries in the basin are now in decline. Only a few tributaries that enter below the main-stem dams have much chance of retaining self-perpetuating stocks of steelhead or Chinook.

Of those tributaries, the Sandy River is the most natural and least dammed. Because of the Sandy's lack of human degradation, it may be the most valuable steelhead and Chinook river in the Columbia River basin. It is my home river and I have fished it for nearly 30 years.

The Sandy River originates high on the slopes of Mt. Hood, about 50 miles east of Portland, Oregon. The headwaters are beneath Reid and Sandy Glaciers at 6,000 feet elevation. From there the river flows west through the Hoodland Corridor. It cascades past the communities of Welches, Brightwood, and Sandy then turns north to enter the Columbia River near Troutdale, ten miles east of Portland, Oregon. At the mouth of the Sandy River, the Columbia River is tidal.

The dramatic geologic forces that shaped the West Coast also shaped the Sandy River. Her changeable personality includes tectonic stress, explosive vulcanism, glaciation, torrential rainfall, the afternoon sun, and the disintegration and regeneration of huge conifer forests. The river flows through rugged canyons. It has deep boulder-studded pools with clean, gray gravel bars often shaded by the tall, wet green trees.

Weather patterns flowing from the Pacific Ocean stack moisture-laden air against the massive slopes of Mt. Hood. The atmosphere supersaturates and the rain begins to fall. Resident steelheaders tend to disdain days of hot bright sun and long for the misty cloud cover when steelhead come most readily to the fly. In the headwaters of this drainage it rains over 100 inches, and over 100 days a year. This continual flush of clean water and the fact that no heavy industry exists in the basin keeps the Sandy's waters pure.

Summer rains are usually soft, warm soakers, but winter storms can leave deluges of ten inches of rainfall in 24 hours. The river is incredibly variable. Average mean flow is about a thousand cubic feet per second (cfs), but the estimated flow on Christmas Day 1964 was 110,000 cfs. The character of the river is unpredictable. A few inches of water can change the holds. Twenty feet of water can change the whole river bed to the point that your favorite drift is now on the other side of the canyon.

The river bottom experiences terrific bed-load shifts. Because of this, the aggregate never has a chance to compress and remains soft and permeable--easy digging for salmonid tails. These gravel-cleansing floods are essential to the health of the fishery. And because the riparian zone is in such good condition the river drops and clears quickly. The river is fishable most of the time and fishes well when the water flows from 500 to 4,000 cfs.

As the river leaves the steep slope of the mountain, it crosses recent volcanic mud flows and the gradient decreases. The mellowing currents allow smaller gravel to collect. These deposits form an ever-shifting layer that lies loosely over a mantle of hard basalt. Much of the water entering the river has traveled through this aquifer, providing maximum oxygenation for the spawn of anadromous fish. The Sandy River basin contains vast areas of spawning gravel for salmon and steelhead.

Mark Bachmann, co-owner of The Fly Fishing Shop, lives in Welches, Oregon.