Upper, lower basin hydrology differs  

H&N Staff Writer

February 7, 2010

   The dry upper basin is made of geologically younger rocks, which are permeable and allow for groundwater storage. The wet lower basin is made of geologically older rocks that have crystallized and force water to run off, rather than soak through.

   In the Upper Klamath Basin, there are 500,000 acres are under irrigation.   Of those, 190,000 are on the Klamath Reclamation Project, which includes the Klamath and Tulelake irrigation districts. Most of that acreage relies on flows from the Klamath River. Only 100,000 acres are irrigated with groundwater. Irrigators grow crops such as mint, alfalfa and potatoes and raise cattle.   Agricultural and food manufacturing is a $650 million industry in the upper basin.

   The hydrology of the Klamath River basin was discussed last week at the U.S. Geological Survey sponsored Klamath Basin Science Conference in Medford. USGS groundwater hydrologist Marshall Gannett discussed the upper Klamath Basin hydrology and Mike Belchik, a senior biologist with the Yurok Tribe talked about the lower basin.

   Mountains

   The Klamath and Cascade mountain ranges intercept precipitation, causing the majority of rain and snow to fall on the western side of the mountains. On average, Gannett said, 9 to 10 percent of the water that actually makes it out the mouth of the Klamath River to the sea originates in the upper basin.

   “Most of the water coming out the mouth is lower basin precipitation,” Gannett   said.

   But Gannett’s studies show that when the lower basin is experiencing dry conditions, such as it does at the end of summer, more water flowing out of the Klamath River is from upper basin groundwater resources.

   The permeability of the upper basin rock structure allows for large groundwater recharges, relative to the amount of precipitation in the upper basin, Gannett said.

   To demonstrate this, Gannett used flows from the Wood River into Upper Klamath Lake. The flows remain relatively steady because the Wood River is spring fed, while the Sycan River, a tributary of the Sprague River, has noticeable seasonal changes.

   “The Sycan River is run-off fed and peaks in May with the annual snowmelt,” he said. The Sprague River is a combination of spring and runoff fed, showing seasonal variation, but it does not dry up in summer.

   When the upper basin experiences dry and drought conditions, the groundwater recharge is less.

   Gannett showed that a Bly-area well had less water during dry years. Climate change is expected to change the way precipitation falls in the Klamath Basin, but Gannett said the ability to store groundwater in the upper basin will help to buffer the effect to some degree.

Side Bar

Hydroelectric dams and Klamath River flow     

   The hydrology of the lower Klamath River Basin has been more difficult to study because of dams that control water flows in the river, said Mike Belchik, a senior biologist with the Yurok Tribe.

   Belchik made a presentation about the hydrology of the lower basin at the Klamath Basin Science Conference   last week in Medford.

   Belchik said Iron Gate dam, the end of the road for migrating salmon, has artificially steady flows except during very wet years. Water had been coming from the dam at a rate of 1,300 cubicfeet per second for the past 125 days.

   “That’s not characteristic of a natural river,” he said.

   Water released by Iron Gate dam accounts for an annual average of 30 to 40 percent of the water coming out the mouth of the Klamath River, Belchik said. He added none of the hydroelectric dams on the Klamath River protect downstream areas from flood. A flood in 1964 nearly destroyed Iron Gate dam.

   Maintaining cold water flows is of concern to fish, and Belchik said studies are being conducted to see whether irrigation of agricultural lands recharges groundwater resources and adds to cold water input to the river. He also said dam removal may add to cold water flows.