Concerns about the collapse of the Oroville Dam soared today as a massive breach in the main concrete spillway suffered further erosion. Fox News streamed live feed of the damaged spillway, noting that the catastrophic scenario of a sudden breach at California’s second-largest water reservoir would be a different and far graver situation than the concern that prompted sudden evacuation orders Sunday for 188,000 downstream residents.

Mandatory evacuations ended last Tuesday, but the Sacramento Bee reports that not everyone has returned home, and most people have suitcases packed in case they’re ordered to leave again. Nearly 190,000 people were ordered to evacuate  as emergency workers rushed to fortify the structure because of an approaching series of storms.

Now, Northern California, where the dam is located, has been saturated by a massive storm Saturday, causing extensive flooding in the Central Valley below the dam. A network of swollen canals, streams and rivers menaced homes, businesses and roadways in the valley, and there is not yet definitive word on how much water has flowed into Oroville Lake behind the dam.

Workers had been releasing water in hopes of forestalling additional problems, and the California Department of Water Resources website said the elevation at Lake Oroville had fallen more than 45 feet from the height of the emergency spillway as of Saturday morning. The site did not give further information on Sunday after the storm. Another large storm is expected to dump heavy rain over Northern California and add several feet of snow to mountain passes starting Sunday night.

Earlier this week the Department of Defense announced that it had been in touch with the California National Guard and the Federal Emergency Management Agency through the commander of U.S. Northern Command. Northcom provides command and control of Defense Department homeland defense efforts and coordinates defense support of civil authorities. The entire California National Guard, with some 23,000 service members, is on alert status.

The impact on the entire U.S. of the failure of the Oroville Dam is incalculable, as the dam and lake are the linchpin of California’s government-run water delivery system, sending water from the Sierra Nevada for agriculture in the fertile Central Valley and for residents and businesses in Southern California. The Central Valley is one of the most productive agricultural regions in the world, providing more than half of the fruits, vegetables and nuts grown in the United States. more HERE, HERE and HERE.