Hydrology View map: JPG | PDF Relative Water Temperatures View map : JPG | PDF

The Sandy River travels 56 miles before flowing into the Columbia River near the city of Troutdale. Many of the tributaries that flow into the Sandy River, including the Salmon and Zigzag rivers, originate from glaciers on the western slopes of Mount Hood. These glacial streams carry both coarse and fine sediment loads, and help sustain cold summer stream temperatures.

Minimum stream flows generally occur during September and October. Peak flows in the watershed most often occur in December and January.

Although water quality conditions in the Sandy River Basin are generally good and suitable to support salmon, seven streams have been identified with compromised water quality for at least part of the year due to high water temperature and bacteria. High temperatures (above the optimum 16°C for rearing and 13°C for spawning) have caused parts of the lower Bull Run River, Gordon Creek, Salmon River, and the lower Sandy River to be listed as water quality-limited. Loss of shade, diversion of water from streams, and stormwater impacts can heat the waters above their optimum temperature. Several fish species native to the Sandy River Basin rely on cold waters to remain healthy throughout their life cycles. This Oregon Department of Environmental Quality (DEQ) has developed standards and regulations to protect water quality and fish for waterbodies in Oregon designated as water quality limited on the 303(d) list. Click here to read about water quality in the Sandy River Basin.

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