Lake Isablla
By Clari Massimiliano / Shutterstock

By Steve Lafond
Special to the Valley Ag Voice

As outlined in the State of California Department of Water Resources February 1, 2020 Report on Water Conditions in California, the Kern River was forecast to flow at a 66% of normal clip during the spring and summer months of 2020. However, due to a bone-dry month of February 2020, those expectations have been torpedoed. Based upon the latest available data, the Kern River is now slated to yield only 44% of its normal amount, or roughly 200,000 acre-feet, during the 2020 April through July snow melt period. 

The severity of dryness has rearranged the record books. Both of the cities of Sacramento and San Francisco recorded zero rainfall during February 2020, something that has never occurred over the period of record dating back to the 1870’s. Snowpack accumulation in the Kern River Basin, which looked promising back in late December of 2019, has actually diminished over the last 8-10 weeks, a result of lack of storm activity coupled with above normal temperatures. Unfortunately, this comes during a time of the winter season when, historically speaking, snowpack accumulation in the Kern is usually at its heaviest.

A shortfall in surface water supply is likely to impact Kern County farming operations in 2020, despite the abundance of carryover storage in most California reservoirs resulting from last year’s much above normal Sierra snowpack, including Isabella Reservoir. Without a dramatic turn-about in current water supply conditions, expect a substantial portion of this year’s anticipated agricultural water shortfall to be offset by groundwater pumping. In accordance with California’s Sustainable Groundwater Management Act, signed into law by Governor Jerry Brown on September 16, 2014, several local water districts will be operating under terms and conditions of a recently developed groundwater sustainability plan, issued to the State DWR in January of this year, for critically over drafted high and medium priority basins, such as the southern San Joaquin Valley portion of Kern County.

Facts, Notes & Highlights

March on the Kern

March 1983–During the period of March 1-2, 1983, heavy rainfall of up to 7 inches fell in Kern County, including 6.50” at Frazier Park and 1.97” at Isabella Dam. Flash flooding occurred in the Tehachapi Mountains and the Caliente Creek watershed. The peak flow from the Caliente Creek into the southeast end of the San Joaquin Valley was estimated at 15,000 cubic feet per second (“cfs”). The resulting flood devastated Caliente and Lamont causing an estimated $58.7 million in destruction. A total of 1,973 homes in Lamont alone were damaged or destroyed – over half of the town. Roads, city infrastructure such as domestic water supply lines and sewer lines were all destroyed. Public schools, parks, and businesses were flooded. Agricultural lands were obliterated. Irrigation works were washed out. In the town of Caliente, 77 people were rescued by helicopter. The wet, brutal series of storms resulted in continued flooding through the 13th. Over 33 roads were washed out in Kern County and two 100 car trains had to be abandoned after water washed out parts of tracks.

March 4–On this date in 1978, .96” of rain was measured at Isabella Dam headquarters, marking the fourth consecutive day of measurable rain at the project. The lengthy early March storm period rocked the upper Kern, lending to a mean inflow to Isabella Lake of 6,559 cfs and a full Kern River natural flow of 7,683 cfs, a record high for this date dating back to 1894.

March 11–On this date in 1995, the Kern River North Fork soared to an instantaneous flow rate of 7,162 cfs as of 3:00 a.m., while 1.19” of rainfall was recorded at Isabella Lake Corps headquarters. The same storm pounded the Central California coastline with epic rainfall totals of nearly 9 inches recorded at Morro Bay.

March 21–On this date in 1991, Isabella Dam received .05” of precipitation, the 14th day of measurable rainfall at the project during the first three weeks of March 1991. Additional rainfall over the period of March 24-26, 1991 helped push the month precipitation total to 6.43”, maximum of record for the month of March. Chagoopa Plateau snow sensor, situated at 10,300’ elevation in the Kern River Basin, increased in water content from just 7.9” on March 1, 1991 to 20.9” (96% of normal) by months end.

April on the Kern 

April 5–On this date in 1958, .99” of rain was measured at the Corps lake headquarters while 1.72” was captured at SCE Co.’s KR#3 Intake gage. For the month of April 1958, a total of 2.77” of rain was collected at Isabella Lake, maximum of record. This lofty precipitation total was one of only three times more than 2.00” has fallen at the lake during April, the last occurring 53 years ago (April of 1967 with 2.75”).

April 12–On this date in 1982, a warm, heavy rain saturated the Kern River Basin, causing a rapid rise in flow of both the North and South forks. At Kernville, the North Fork rose from a low of 863 cfs on April 10, 1982 to a peak instantaneous rate of 12,720 cfs as of 5:00 p.m. on April 11, 1982. The South Fork Kern River near Onyx soared from 356 cfs to a peak discharge of 3,007 cfs by the early morning hours of April 12th.

April 29–On this date in 1969, mean regulated flow at Kern River First Point of Measurement near Hart Park was 6,442 cfs while Isabella Dam mean outflow was reported at 5,891 cfs, resulting in streamflow accretions to Kern River below Isabella of 551 cfs. During April of 1969, accretions from minor tributaries located below the dam totaled 40,391 acre-feet, the largest amount recorded for any one month since Isabella Dam operations began in April of 1954.

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