Another series of storms has brought heavy rain and strong winds to much of California, causing widespread flooding, especially in Northern California, and threatening the structural integrity of the Oroville Dam, the nation’s tallest. Counties and cities near Lake Oroville have issued emergency evacuation orders for 188,000 residents due to eroded primary and emergency spillways which could lead to the uncontrolled releases of water.
Drought conditions have continued to improve, with about 11% of the state experiencing severe to extreme drought, compared to 20% last week. The area no longer experiencing short-term drought effects has increased from 40% to 41.5% over the past week. La Niña conditions have subsided and normal sea surface temperatures in the Northern Hemisphere are expected to continue through spring 2017. Despite these improvements, drought impacts on overdrafted groundwater basins, forests, and aquatic species in California are long term and will take multiple above-average precipitation years to be resolved.