From Water Deeply (Laura Feinstein, Peter Gleick):
Let’s not let a good crisis go to waste: Here are six important conversations that need to happen in the aftermath of problems at Oroville Dam in Northern California.
A critical question is whether the main spillway will be serviceable for the remainder of the winter. Dam managers must continue to release water down the damaged main spillway to maintain flood space behind the dam for coming storms and spring snowmelt. Bill Croyle, acting director of DWR, told the Sacramento Bee this past Sunday that his agency is not seeing further erosion of the main spillway at current flow levels of 100,000 cubic feet per second (cfs). Managers also shut down the turbines at the base of the dam that normally release up to 15,000 cfs because of downstream obstructions.
If another storm sends water into Oroville Lake faster than it can be released via the turbines and main spillway, then water could again over flow the concrete wall that forms the top of the emergency spillway. If the hillside beneath erodes further, this wall could collapse or be undermined, sending massive amounts of water downstream causing damaging, life-threatening floods.
Sacramento Bee has a concise recap of events here.
Can We Prevent These Types of Dam Crises in the Future?
It’s well-documented that the United States has chronically underfunded dams, levees, drinking water and wastewater infrastructure for years. The Association of State Dam Safety Officials estimates the cost of known needed repairs for the country’s 2,000 deficient, high-hazard dams at $21 billion. Drinking water, wastewater, waterways, ports and levees need repairs too. The American Society of Civil Engineers in a 2013 report put the unmet funding needs of our water infrastructure at $187 billion by 2020 (calculated in 2010 dollars).
Had the emergency spillway been lined with concrete, as was recommended in a motion filed by Friends of River, Sierra Club and South Yuba River Citizens League in 2005, it might have prevented the erosion that occurred this past weekend. In hindsight, it’s easy to see that this would have been a worthwhile investment compared to the cost of repairs, mass evacuations, and environmental impacts.
But the Oroville spillway crisis reveals another important question we haven’t been asking about our underfunded infrastructure. That is: How much money do we need to budget for upgrades that are becoming necessary as engineering standards improve and climate change imposes greater pressures on the system? We may be on the hook for even more money than we realize.
Where Are We Going to Get the Money to Repair the Spillways?
Preliminary estimates to repair just the main spillway are in the range of $100m-$200m, according to Bill Croyle at DWR. The State Water Contractors that get their water from the State Water Project will likely have to pay for at least part of the repairs, and they will pass the costs on to their ratepayers. Three more things to note.
First, these expenses are likely to cause increases in costs for ratepayers, some of whom are already struggling to pay their water bill. Second, we should expect a vigorous debate as to who else should help foot the bill. Should residents of the floodplain pay for a portion of the repairs, since they benefit from flood control? Should all California taxpayers chip in via allocations from the General Fund or Proposition 1 Bond monies? Third, these types of public works projects cannot be incentivized with tax deductions to private companies looking to build profitable projects, as the Trump administration has proposed.
Are We Going to See More Water Emergencies as the Climate Changes?
Scientific models project, and observational data corroborates, that California’s climate is becoming more variable, with hotter, longer droughts and bigger precipitation events. The state’s water system was designed for a climate we no longer have. More extreme events are going to test the limits of our infrastructure and reveal new weaknesses in the system.
What Does This Mean for the Feather River Ecosystem?
In general, storms are good for rivers. California’s river ecosystems are adapted for big pulses of water in the winter. But the Feather River, where Oroville Dam is located, has been heavily altered by people, so these storms play out differently than they did before the river was dammed and leveed.
Feather River Hatchery spawns about 30 percent of the fall-run Chinook salmon in the state, as well as large numbers of spring-run Chinook and steelhead trout. Spring-run Chinook and Central Valley steelhead trout are listed as threatened under the Endangered Species Act; fall-run Chinook are still an important species for commercial fishing. Hatchery staff relocated five million juvenile salmon to a nearby facility, and have rigged a system to bring in municipal water to support the 1 million steelhead still at the hatchery. If hatchery operations go awry, it could impact populations of these valuable species.
The Feather River itself is still an important spawning ground for natural salmon and steelhead. But levees mean the river is restricted to a narrow channel, where rapid flows scour out the nesting grounds. Meanwhile, influxes of sediment and debris are likely to damage spawning grounds in the short run.
The Oroville Dam and the levees downstream were built for the joint goals of water storage and flood prevention, but floods are healthy for both the river and the floodplain. Long term, California should be thinking about places where it can move levees and allow rivers to reconnect with their floodplains.
Nobody wants to see people evacuated from their homes because of a potential natural disaster. The silver lining to a crisis is that it can generate political will to deal with unpleasant, chronic problems. The problems at Oroville Dam are linked to unresolved issues we have with funding our infrastructure, adapting to climate change and restoring natural ecosystems. Let’s move forward in ways that address the immediate emergency and the long-term problems.
Meanwhile, here’s a report about US dam safety from Brett Walton and Circle of Blue:
The near-failure on Sunday evening of the auxiliary spillway at Oroville Dam and the ongoing emergency operations to contain flood waters in California’s second-largest reservoir and shore up its eroding outlet are a tale of caution for the nation’s aging dam fleet.
“I think it should give many people reason to step back and take a hard look at things, including California,” wrote Martin McCann, director of the National Performance of Dams Program at Stanford University, in an email to Circle of Blue.
The Oroville emergency is unfolding in a state with a dam safety program widely regarded as the nation’s strongest. McCann agreed that California’s efforts to prevent a partial collapse of Oroville’s auxiliary spillway should be a wakeup call for other states with less vigilant dam regulation. Alabama, for instance, has no state dam oversight at all.
Already the top spending state for dam safety, both in total dollars and inspectors per dam, California increased its program budget by six percent between 2014 and 2016, to $US 13.3 million. The Department of Water Resources’ Division of Safety of Dams has roughly one employee per 20 state-regulated dams. That is far greater than the national average of one employee per 200 dams, according to data from the Association of State Dam Safety Officials.
“California has had a strong dam safety program for many decades,” McCann said. “It’s well-funded, well-staffed, and they inspect regularly.”
Dam safety experts cite money as the most significant impediment to safer dams. Though California spends big on oversight, the cost of repairs has emerged as a factor in the Oroville emergency. Reporting from the Mercury News revealed that state and federal officials rejected an appeal from three environmental and civic groups in 2006 to line the auxiliary spillway with concrete. The groups were concerned that the topsoil on the hillside spillway would erode if it were ever used. February 11 was the first time that water flowed over the auxiliary spillway since the 770-ft-tall dam was completed in 1968. Use of the auxiliary spillway was necessary because of damage to the main spillway and inflows to the reservoir that nearly matched the flow of the Mississippi River at St. Louis. Officials had to evacuate as much water as quickly as possible.
Most of the more than 90,500 dams in the U.S. Army Corps’ national dam database, however, are not behemoths like Oroville. Most instead resemble Twenty-one Mile Dam, a 47-foot-tall earthen structure in Elko County, Nevada. Owned by Winecup Gamble Ranch, a 948,000-acre livestock operation, the dam burst on February 9 during heavy rain. Flood waters released by the dam chewed through 200 yards of Highway 233, which remains closed.
Two-thirds of U.S. dams are privately owned and often owners do not have funds for maintenance or repair, according to Lori Spragens, executive director of the Association of State Dam Safety Officials. Most U.S. dams are more than 50 years old and an unknown number are not built to current safety standards. The association estimates that $US 18.7 billion is needed to repair high-hazard, state-regulated dams. High-hazard dams could kill people if they failed…
The pressure on Oroville will not soon let up. The watershed above the dam is expected to get as much as eight inches of precipitation through February 21. Then in the spring, the massive snowpack, measuring twice the historical average in some spots, will melt. The California Nevada River Forecast Center estimates that water flows in the Feather River, which drains into Oroville, will peak on April 29.
All of which has state officials on constant alert. “We want to complete assessments, do corrective measures on the emergency spillway, and get it ready for potential future use here in the coming weeks or months,” said Bill Croyle, acting director of California Department of Water Resources.