The design of the flood control system is complex and has many moving parts, but if each cog in the wheel operates to its capabilities, major flooding can be prevented, officials say.
"The whole system is designed to alleviate flood damage, and I think it's working properly at this point," said Andrew Stresser, general manager of Levee District 1 in Sutter County.
The district is primarily responsible for the operations and maintenance of the levee located on the west side of the Feather River in south Yuba City.
"We make sure the structural integrity of the levee is sound," Stresser said. "We do monitor flows and weather patterns. I think the most recent storm was a good test of the levees and everything seems to be operating correctly at this point."
While heavy rains test drainage systems within municipalities, what happens in the mountains — particularly with the snowpack — is the true test on the state's flood control system.
How it works
"The biggest reservoir in the state is the water stored in the snowpack," said Mike Inamine, executive director of Sutter Butte Flood Control Agency. "The long-term reliability of the state's water supply depends on the availability of snowpack. That large reservoir releases water slowly into downstream reservoirs over time throughout the water year."
Snow melt funnels into a reservoir. The reservoir, which is a method of storage, is also used for flood protection because releases can be monitored in order to relieve pressure on rivers downstream.
Without a dam, the possibility for flooding increases because the high volume of water from runoff becomes essentially uncontrollable once it enters the river, Stresser said.
Before and during a heavy storm, reservoirs will release more water to make room for expected runoff from the mountains. The increased flow raises the river levels.
When enough water enters a river, agencies and the state will utilize bypasses as a flood-control method. A bypass is essentially an area used to alleviate a main water channel and act as a second storage to the reservoir upstream.
A weir is a gate or structure designed to open when water in a channel reaches a high level. By opening a weir, water flows into a bypass and spreads out, relieving a water channel from stress, Stresser said.
For the first time in 11 years, the Department of Water Resources opened 20 of the Sacramento Weir's 48 gates during the storm this week.
According to a DWR press release, "Opening additional gates allows DWR to maintain a consistent level on the Sacramento River… These flood releases relieve pressure on the Sacramento River and reduce the risk of urban flooding in Sacramento."
In total, there are five weirs along the Sacramento River that convey water into a bypass, Inamine said.
Significance of storm
Inamine said a lot has been done in the past decade or so to improve flood control and flood management throughout the state.
He said agencies that monitor reservoirs have improved forecasting methods and coordinate operations much more efficiently.
Setback levees and infrastructure strengthening projects have made improvements to the reliability of the levees.
A number of laws have been passed that make flood control system improvements a priority and help with management. Emergency operation services have become much more widely utilized.
Overall, Inamine said people are more aware of the dangers of flooding now and the need for flood control and flood management.
Stresser said it's hard to compare the most recent storm with storms in the past that caused major flooding in the area.
"When it flooded in 1997, the conditions were much different," Stresser said. "We had high snowpack, and the snow in the foothills was significant. Then the Pineapple Express came in and dumped a lot of water on the system. Things were different this year, but if all our reservoirs were full, this could have been a much more significant event."
Inamine agreed with Stresser that the recent storm was much less significant than the one in 1997 that caused certain areas in the region to flood. However, he said the potential for flooding is not over.
"We aren't completely through the flood season yet," Inamine said. "This could be the beginning of a much longer storm season."
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