Feb 16, 2017

Lake Oroville Water Levels Drop

Oroville, CA
USA
by
Jeff Masters and Bob Henson
,
Category 6
Predicted 7-day rainfall amounts in northern California beginning on Thursday, February 16. Image: NWS Sacramento
Predicted 7-day rainfall amounts in northern California beginning on Thursday, February 16. Image: NWS Sacramento

The water level at the troubled Lake Oroville reservoir in California continued to drop on Thursday morning, even as rainy weather moved into the region. The lake level fell by nearly 5 feet in the 12-hour period ending at 6 a.m. PST Thursday, to 869 feet, about 30 feet below its capacity. According to reports from the Sacramento Bee, state water officials continued to release 100,000 cubic feet per second (cfs) of water from the lake’s main spillway, and damage to that spillway has not worsened. Water was flowing into the lake at 34,000 cfs Thursday morning. About one half inch of rain is expected in the area on Thursday, with another half-inch on Friday (the rains will be much heavier in Southern California, see embedded tweet below.) Dam operators are expecting inflows of up to 50,000 cfs through Friday, so the lake level will continue to fall as long as the main spillway continues to release 100,000 cfs of water. During last week’s heavy rains that caused the reservoir to overflow, inflow peaked at 197,000 cfs. On Sunday, Monday and Tuesday, another very wet Pacific storm system is expected to dump at least three inches of rain on the area. This is about the same amount of rain that fell during the storm that caused inflow rates to reach 197,000 cfs last week. If the upstream rainfall amounts also end up being similar in magnitude to last week’s storm, we can expect Lake Oroville to begin rising by Monday. However, assuming that dam operators can continuously release 100,000 cfs of water from the reservoir during the coming week, it appears unlikely that the lake will reach 900 feet and force usage of the emergency spillway again.