Thursday, 02 February 2023

Stream, lake, snow levels lower this year

LAKE COUNTY Hydrologists are saying that a recent snow survey in the Mendocino National Forest shows one of the driest years in decades, at the same time as county officials say that less precipitation overall has resulted in low stream and lake levels.


Phebe Brown, spokesperson for the Mendocino National Forest reported that snowfall in the forest in February replenished the nonexistent snowpack on Anthony Peak, elevation 6,200 feet. Forest hydrologist Bob Faust said Anthony Peaks sits in the middle of the forest, between the Sacramento River and Eel River watersheds.


Thanks to that snow, Anthony Peak reached 92 percent of average depth and 67 percent water content, Brown reported.


Since the February survey, however, officials say snow and moisture levels in the forest have plummeted.


A March 30 snow survey conducted by Covelo Ranger District employees Conroy Coleman and Jordan Saylor revealed that the snow pack had dwindled to 26 inches (40 percent of average depth) and 12 inches of water (43 percent of average), Brown reported.


Saylor and another forest staffer, Fred Burrows, checked out the Plaskett Meadows snow course on April 2, said Brown. Seven of the 10 snow sample sites were bare, said Brown. Average snow depth was 2.6 inches with only 1/10 inch of water.


"This is the driest April reading on record since 1944," said Faust. "More recent dry years were 1972 and 1997 when there were 6 to 7 inches of snow and about 1 inch of water content."


Brown said Mendocino National Forest has been measuring winter snow depths and moisture content since 1944 and the averages are calculated based on all those years.


Precipitation from Anthony Peak drains down the Grindstone watershed, into Stony Creek and the Black Butte Reservoir, ending up in the Sacramento River. Precipitation from Plaskett drains to the Black Butte River and into the middle fork of the Eel River, Brown reported.


The sparse snow pack will affect area lakes and streams, Faust said.


Water in Lake Mendocino dropped from last month's 101 percent of average to 90 percent, Brown reported. The same was true for Black Butte Lake in Glenn County, with water levels dropping from 99 percent of average to 88 percent.


The Central Valley Project water regulators are keeping Shasta Lake and Lake Oroville full at 107 percent and 113 percent of average, respectively, Brown reported.


Past snow measurement records show that there are years when the snow pack has increased during the month of April. However, Faust cited a report from the state's climatologist, which says that a La Nina pattern is expected to develop in the Pacific over the next three months, which means ocean temperatures will become cooler than average near the equator.


Those conditions are expected to lead to below normal precipitation throughout California for the rest of this year and into the winter.


"Longer term concerns with a strong La Nina are dry to drought-type weather conditions next winter for the western U.S.," the report stated.


Brown said the Covelo Ranger District snow survey team will make one more reading this season on Anthony Peak prior to May 1. The measurements are a part of the statewide California Cooperative Snow Survey program run by the California Department of Water Resources.



Lake County doesn't rely on snowpack


Tom Smythe, water resources engineer in the county's Water Resources Division, said Lake County is definitely drier this year.


The county's watersheds aren't dependent on snowpack, Smythe said. “If we were, we'd be in big trouble,” he said.


However, rainfall has been sparse this year, Smythe said.


Rainfall levels tracked by the Cobb Area Water District and the City of Lakeport show a much drier year this year, especially as measured against last year's extremely rainy conditions. Cobb's measurements show totals at roughly half of average. In Lakeport, numbers from the first four months of of this year amount to about 20 percent of last year's total.


The result is lower levels in local creeks, said Smythe.


A US Geological Survey stream gage reading for Kelsey Creek, one of the creeks responsible for the most flow into Clear Lake, was at 16 cubic feet a second (cfs) on Friday, substantially below the median flow of 39 cfs.


Putah Creek east of Hidden Valley Lake is flowing at 30 cfs, while the median is 93 cfs, according to the US Geological Survey stream gauges. The North Fork of Cache Creek at Hough Springs (above Indian Valley Reservoir) is flowing at 28 cfs, where the median flow is 60 cfs.


Smythe estimated that the other streams are probably in similar flow conditions.


"This will reduce late season groundwater recharge and probably lead to lower groundwater levels through the summer and fall," Smythe said. "We do not have sufficient information on how much lower than normal groundwater levels will be this year."


Smythe said Water Resources recently completed measurements of 86 wells in the county's major water basins in order to know local groundwater conditions. “Our groundwater basins are pretty close to normal,” he said, thanks to above-normal rainfall from previous years.


The ultimate result will be seen in Clear Lake. The lake on Friday was at 5.85 feet Rumsey, below the median level of 7.18 feet Rumsey. The lake peaked at 6.14 feet Rumsey on March 30, said Smythe. The lake's average level is 7.21 feet Rumsey.


Despite the drier conditions this year, Smythe said the county has been in an unusually wet period. This will be the fourth year in the last 15 years that Clear Lake has not filled above "full," which is 7.56 feet Rumsey, he said.


“Basically, we've been full for five years in a row,” he said, adding that he's also seen several-year runs of a lake that didn't hit the full mark.

The lake also is a its lowest point since 2001, when the lake's highest point was 5.20 feet Rumsey.


"We don't anticipate any major problems in Clear Lake due to the lake level," he said.


The biggest impact will be to Yolo County Flood Control, said Smythe, which will have approximately 85,000 acre-feet less available form Clear Lake for irrigation supplies in Yolo County, down from its normal annual allocation of 150,000 acre feet.


Yolo County is already warning its farmers about the water shortage, he said.


E-mail Elizabeth Larson at This email address is being protected from spambots. You need JavaScript enabled to view it..


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