May 25, 2010

   Though all water in the Basin originates as snow melt and rain, Marshall Gannett said, the groundwater resource fed by that precipitation is a key link in the region’s hydrology. When weeks go by without rain, that groundwater sustains the environment and ensures irrigators have some water into early fall.

   “It does mean that late in the season those flows are going to be there,” Gannett said.  

   Historic lows

   Klamath Project irrigators this year will receive only a third of their usual irrigation water, and some won’t receive any. Lower-than-average precipitation has contributed to historic lows in Upper Klamath Lake, the Project’s chief water source.

   Farmers and ranchers are idling land or planting on rented land elsewhere that has a well for irrigation. Others have applied for groundwater permits that allow them to pump that water for irrigation.     

  The bulk of the Basin’s water originates on the eastern flanks of the Cascades because they receive the most snow of the mountains in the region.

   Crater Lake’s slopes receive more than 65 inches of precipitation on average each year, while Klamath Falls receives about 13. Nearly three quarters of the precipitation that falls in the mountains comes from November through March as rain and snow, according to a USGS report coauthored by Gannett.  

   Volcanic soil

   The region’s volcanic, porous soil also is crucial to this system. It allows all that water to easily seep into the ground and make it to aquifers beneath the ground.

   Gannett said the three primary sources of inflow to Upper Klamath Lake — the Wood, Williamson and Sprague rivers — are heavily dependent upon that groundwater resource.

   The Wood River receives the bulk of its water from springs on the eastern edge of its river valley, while spring-fed Spring Creek is a major source for the lower Williamson River.

   That doesn’t mean that direct snow melt and rain runoff don’t contribute to river flows. Gannett said it makes sense that inflows to the lake are below average this year, as precipitation was below average during the winter.

   River flows

   But the river flows should be fairly close to average during the summer, when all snow melt is gone because the region has had wet winters in the last few years that fed into the groundwater system.  

   “They’re as high now as we’ve seen in the 1980s,” Gannett said of the flows coming from Spring Creek.

   That groundwater resource has its limits, though.

   During the 2001 water crisis, numerous irrigators below the lake dug wells to bring water to their fields when they didn’t get water from the lake, said Doug Woodcock, manager of the groundwater section for the Oregon Water Resources Department.  

   The result was a steep drop in how close groundwater was to the surface in the areas around the Klamath Reclamation Project. Woodcock said the water level in the aquifer in that part of the Basin dropped 15 to 20 feet in some places, requiring some people who already had wells to deepen them.

   A report Gannett helped write on the region’s groundwater indicates that groundwater pumping has increased by 50 percent since 2001.  

   Spring-fed sources

   Woodcock said that while the groundwater in that part of the region isn’t responsible for the water flowing into Upper Klamath Lake, it still provides water to spring-fed water sources, such as Big Springs near Bonanza.

   Groundwater users in that area already have conditions on their permits to keep the Lost River, which has bacteria in it that could contaminate the otherwise clean springs, from flowing into the spring source.

   “It’s a very real issue, and we do keep an eye on it,” he said.