Janine Hasey has lived through several northern California floods. The county director for the University of California Cooperative Extension offices in Sutter and Yuba counties witnessed several major flood events in the region including in 1997 but none rival last winter.
Most notably is the evidence of orchard collapse, or the widespread death of orchards because of long-term flooding.
“I’ve never seen this kind of collapse in 35 years,” Hasey said.
Orchard collapse is in peaches and walnuts as the death of entire orchards begin to unfold. The cause of death can be traced back to long-standing water in the orchards, which remained as trees came out of dormancy and began to bloom, producing leaves and expanding root systems.
Record rain
Yuba and Sutter counties are located near the confluence of four major river systems, including the Feather, Sacramento, Yuba, and Bear rivers. The Sutter Bypass, part of a natural overflow area called the Sutter Basin, also plays a major role in the region. The basin is incorporated into a flood control project that takes pressure off the Sacramento River during high flow events. Yet by doing so it spreads water across thousands of acres, including farm land.
By June, the city of Sacramento boasted its third-highest rain season in recorded history at nearly 34 inches, not far behind 1982/1983 and 1889/1890, at first and second, respectively.
Exacerbating the season for growers in the south Sacramento Valley, particularly those along the Feather River, was the situation at Lake Oroville and the spillway at Oroville Dam in February.
In early February, the concrete spillway that channels water from Oroville Dam to the Feather River collapsed when the hillside that supports the spillway eroded from weeks of heavy rain. Soon after, the initial failure of the main spillway, inflows into Lake Oroville from the Feather River watershed exceeded the volume in controlled flows. This caused the lake to rapidly fill and spill in uncontrolled releases over the emergency spillway for the first time since the earthen dam was built in the late 1960's.
In the weeks following, the California Department of Water Resources attempted to control lake levels. The Feather River rose and fell rapidly, and caused river banks in the Marysville area to sluff off into the river channel.
With each rise above flood stage a new pulse of water flowed across farmland in the region. As river releases were abruptly lowered, millions of cubic yards of earthen river banks were released into the river channel.
River Oak Ranch
Brad Foster leases River Oak Ranch north of the town of Marysville. The 400-acre orchard of mostly walnuts with some pecans were affected by three separate flood events - water at times greater than 10 feet deep flowing rapidly through the trees. The high flows left a field of debris from upstream farms that included trees, soil, irrigation pipe and other materials.
Though the impacts were significant, Foster said his damage was mitigated because he allows weeds and grasses to grow as cover crops during the winter months. This helped preserve some of the soil in his orchards which otherwise would have flowed downstream with other debris.
That his orchards flooded this winter isn’t a point of contention with Foster; he understands and accepts the risk of farming in the river bottom along the Feather River.
His point is the management decisions made by state officials that rapidly raised and lowered the Feather River caused significant river bank erosion.
By late spring, Foster lost over two acres of buffer zone that protected the river from his farming operations. The zone was once a 200-foot riparian strip with native oaks and grasses that helped keep spray drift from his 400-acre walnut block from getting to the river.
“This just caused the river to get wider and shallower,” he said.
In spite of the river-bank losses, Foster says he lost no trees directly from the floods, though there was significant erosion around the base of some trees in his orchard due to eddies created by fast-moving water. He intends to fill the holes with soil deposited on his ranch from upstream sources.
He will spend the summer moving soil to rehabilitate his orchards which he still irrigates with sprinklers.
Foster’s fungicide costs were high this year due to the wet season.