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Hi Ray76, (& others getting up to speed).. That "clip" section of the archives was the result of the original design findings in the HYD-510 analysis. That section revealed a series of "engineering judgement" chain of events that started this hillside erosion consequence "hot potato" (Emergency Spillway ES).

Even though the "cash is flowing" - (FR KC Burke quote) - the new proposed concept design Emergency Spillway with RCC buttressing and a partial downhill "apron" still has a serious design flaw of repeating the whole crisis chain of events. DWR is making the same "engineering judgement" shortcoming as in the early "Politics of Engineering" back in the 1960's. The links below, (first one has the clip you noted), provide a series of clickable reads to cover past postings of these discussions (& graphics).

FRpost links: (volumes of photos, diagrams, discussion):

Politics of Engineering Judgement: How Failure is introduced…

DWR's 1960's Split spillway "engineering political solution" coming back to haunt the future? (new Failure mode of the entire dam)

How can the spillway be brought to modern design standards based on spillway design history and other dam failure knowledge gained?

Modern Spillway Design vs Oroville Design - 2 Dam Failures, Drain Pipe, Rebar, "Hydraulic Jacking", "Void" Finding by Radar

More:

The panel report also said that while touring the spillway, consultants spotted “extraordinarily large” amounts of water gushing out of drains...

Expert Board of Consultants swizzled flow number specifications for the New Main Spillway and the New Emergency Spillway. Why?

3D Model simulations of a "flip bucket" & how a spillway flow could "jump a distance".. Concerns in the force vector stresses in anchoring such a design

Citing potential security risks, state and federal officials have blocked the public’s ability to review the latest report from an independent panel of experts brought in to guide state officials’ repairs at the crippled Oroville Dam.

THIS is the DWR letter that triggered the response in a block of the public's ability to review the latest report from the independent panel of experts (functional "security" weakness)

How can the spillway be brought to modern design standards based on spillway design history and other dam failure knowledge gained?

DWR's Project Safety Compliance Report strategy will come back to haunt them

Target Reveals Broken Section Spillway Shift? - Up to 1.16 inches movement downslope

New DWR photo has a high resolution capture of the upper main spillway Optical B/W Stripe "Shift" Target. The Target is observable on the far spillway sidewall. A special High Resolution zoom of the target reveals a "shift" of the damaged section of the spillway downslope from up to 1.16 inches (0.87 inches mean). DWR has not said anything to the public regarding this substantial "broken section shift". THIS SHIFTING damaged section of the full width of the spillway chute does NOT have ANY ROCKBOLT ANCHORS. The rockbolt anchors start immediately above this optical target location. Thus, the "shifted" section is over 52 feet in length and is anchored on the orange/red highly weathered rock. note: Image processing is required to determine the Black & White stripe shift distance as the original 25+ MegaByte image is protected by DWR from download of their gallery in photoshelter. note: all camera angle curvatures were compensated for in the analysis.

"First Sighting" - On the April 14 restart of the spillway, a DWR "drone" view of the Target was not "edited", thus a snip capture (couple of seconds) Target image became available for the first time. This also revealed the presence of the same downslope shift, but only at a 1024 HD resolution. However, I was waiting for confirmation from a higher resolution image. This image was posted to DWR's photo gallery April 19. note: As the April 14 "Drone" footage was taken during the recent restart of the spillway, the "shift" would have occurred in the prior spillway release started on March 17, 2017. At that time, DWR ran the spillway up to 50,000 cfs on March 17th (total outflow data) but by March 21st the flow was reduced to 40,000 cfs. It may be possible that the damaged section downslope "movement" was detected at the higher cfs rate and then was slowed due to this detected movement. Now DWR is operating the spillway flow at 35,000 cfs, perhaps for good reason.

DWR Photo Metadata: "A mist cloud rises from the Lake Oroville flood control spillway, as the California Department of Water Resources continues to discharge 35,000 cubic feet per second (cfs) of water from the spillway to continually manage lake levels. Photo taken April 19, 2017."

Note the camera mounted on the near spillway sidewall where the chain link fencing is cut away. There is a second camera mounted near the end of the damaged section at the water fall.

Optical Target panels Bolted onto Damaged Sidewall to detect downslope "shifting". This section is approx 54 feet upslope from the plunge pool where concerns were that this part of the upper spillway (slabs & sidewall) would fail and break away.

New April 19 DWR photo captures a view of the Optical Target Panel. Hi Resolution zoom of the target reveals a "downslope shift" of up to a max of 1.16 inches with a 0.87 inches mean avg. note: EXACT value not released or noted to public by DWR.

SacBee Article: Groups demand transparency on Oroville Dam spillway repairs - Wants Emergency Spillway concreted to Feather River

Article excerpt: (emphasis mine):

"A coalition of environmental groups that had warned Oroville Dam’s emergency spillway was fatally flawed long before it nearly washed away this winter is demanding that federal regulators open up dam repair plans for public vetting.….. In a filing Wednesday with the Federal Energy Regulatory Commission, a coalition of environmental groups led by Sacramento-based Friends of the River also said it was concerned that the state Department of Water Resources is only going part way in repairing the emergency spillway. DWR’s repair plan calls for replacing the dam’s main spillway, which cracked in two in early February, and partially lining the emergency spillway with concrete. Ron Stork, a policy analyst at Friends of the River, said the plan for the emergency spillway makes sense but only as an interim measure. He said the ultimate goal should be to line the emergency structure from top to bottom. “You want a spillway all the way down the hillside,” he said in an interview.

= = end excerpt

This re-creation graphic is what the groups are concerned about. A new design failure mode from a mandated rated 369,000 cfs flow capacity "maximum flood specification" down the 80-90% unprotected hillside. Massive erosion will clog the Feather River & send silt downstream. Damming of the River could force any Main Spillway usage flow to backflow & via eddy swirl currents that could erode the toe of the main Earth Fill dam, risking total dam embankment stability (collapse sequence). Preventing this new potential "failure mode" requires a significant cost investment to concrete the entire hillside down to the Feather River. The current "New Concept Emergency Spillway design is devoid of any full hillside protection".

Groups demand transparency on Oroville Dam spillway repairs

Another Design Failure in waiting? Board of Consultants required DWR's new design spec to meet 369,000 cfs for the New Emergency Spillway. This is what it would look like - with massive hillside erosion as there is no plans for concrete armoring for hillside erosion protection down to the Feather River.