KRIS Shasta River Tour

Hydrology

The Shasta Valley is in a rain shadow created by the Klamath Mountains, which lie to the west. Moist air masses moving eastward from the Pacific Ocean are drained of their water as they climb over these mountains. Precipitation on the valley floor is only 10 to 17 inches per year. Mt. Shasta, at the head of the valley, often has a heavy snow pack, which then melts throughout the summer. The water percolates down through the lava tubes and pops up as springs on the Shasta valley floor. This helps to keep water flows up and temperatures down in parts of the river, making these sections suitable habitat for trout and salmon.

Big springs pops out of the ground to feed Big Springs Creek. Little Springs Creek flows into Big Springs Ck. at the bottom of the picture.

Rainfall in the Klamath Mountains can exceed 40 inches a year. Most of the water flowing from the upper Shasta River and Parks Creek is captured in Dwinell Reservoir, however, and released throughout the summer for irrigation. The diversion of surface flows and groundwater pumping substantially reduce Shasta River flows during the summer.

Dwinell Dam captures and holds the water flowing from the upper Shasta River and Parks Creek, changing the natural hydrology of the river.

For more information about the hydrology of the Shasta River:

Hydrology section of Shasta/Klamath Rivers Water Quality Study. Department of Water Resources, Northwest District. February 1986.

Climate data from the 1995 Siskiyou County Crop and Livestock Report.