PROJECT ALERT NOTICE (CA) California experiencing a wave of AR storms—Continued, Day 10

Date: Fri, 13 Jan 2017 17:03:40 EST

Summary: Although elevated streamflow levels continue, rivers in California are receding after 10 days of storm events which brought substantial accumulations of rain and snow to many parts of the State.

Today, rivers and streams across in California continue to respond to over 10 days of storm events that brought well above-average precipitation to many parts of the State. To provide some context, parts of California received 20 inches of rain in a week, for areas that typically get 30-40 inches of rain a year. Today, and over the next few days, intermittent, light rainfall or showers are expected for various parts of California, This break in the weather will be brief, however, as another storm system is currently predicted to bring substantial precipitation to all of California beginning next Tuesday. If precipitation forecasts hold true, areas of northern California could receive another 3-7 inches by next Wednesday.

Over half of all USGS streamgages in California remain above the 90th percentile of normal flow today. Since this storm system began on January 4, the USGS California Water Science Center has collected streamflow measurements at over 200 streamgages in the network; a network that includes over 500 streamgages across California.

The California Water Science Center (CAWSC) has 21 crews responding to this event today from all service areas: Ukiah, CA (3); Redding, CA (1); Eureka, CA (1); Santa Cruz, CA (2); Redlands, CA (2); Santa Maria, CA (3); Truckee, CA (1); Poway, CA (4); and Sacramento, CA (4). Some crews are performing measurements today, but most are performing service repairs or maintenance, such as clearing sediment or debris from orifice lines and controls. Currently, no crews are planned to deploy tomorrow or over the long weekend.

Several crews are out today measuring streamflow at sites that have not had measurable flows in several years due to the drought. For example, discharge is being measured at site 11152500 Salinas River near Spreckels, CA, which is flowing for the first time in over 3 years (since October 2013).

Increased turbidity and high suspended-sediment loads caused technical measurement challenges at many sites, requiring crews to rely on mechanical meters, or use acoustic Doppler current profilers with a section-by-section method. Approaches like this made measurements possible at sites like 11143000 Big Sur River near Big Sur, CA.

Crews are also out today measuring discharge and collecting water-quality samples for the USGS Cache Creek Settling Basin Project, a study that examines sediment and mercury loads into and out of the Cache Creek Settling Basin with larger implications for water supply, flood management, water-quality and ecological health.

No safety issues have occurred during this series of storms and all staff have followed USGS field reporting and safety protocols.