The Truth about the Great 2010 La Canada Mud Flood! Part 1: The Lay of the Land

Part 1: The Lay of the Land

Not all adventures are good clean fun.  Some involve going through police barriers to check on your friends to see how they are affected by natural or man-made disasters.  Such is the case now, right in the area where Rusty lives.

In January and February of 2010 people around the country and around the world heard about the devastation caused by water, mud, and debris flows that tossed around cars and two ton concrete barriers like they were a child’s toys.  Few people outside of the area really understand how this happens in the relatively dry Southern California Los Angeles basin.  Rusty Waters has lived in this area his entire life, looking up at the source of the floods every day.

This Adventures of Rusty Waters three-part series explains the lay of the land, how geologic and weather conditions create the perfect storm of huge “debris flows”; exactly what happens in these debris flows, including the great Los Angeles flood of 1933/1934, and what’s happened in the intervening years that the area is still having such problems.  Finally, we’ll look at what the future holds for the little towns of La Canada Flintridge, La Crescenta, Montrose, Tujunga, Sunland, and others that lie in the path of Mother Nature’s fury.

First, let’s take a look at the lay of the land.  To understand Southern California, especially the Los Angeles area, think of a large flat desert.  It is not the kind of big sand dune desert you find in the Sahara or the Sonoran desert in Arizona, loaded with cactus.  The Californian desert is a light crushed rock sort of sand strewn with boulders and covered sparsely with scrub plants.  If you think of that desert as a big square and imagine the left and bottom of the square bordering on the Pacific Ocean, you’re looking at the Los Angeles basin.  That big flat plane would go on and on except that in this area two giant tectonic plates come together.  The Pacific plate pushes up against the North Atlantic plate along the San Andreas Fault.  The forces involved are unimaginable.

As a result, the basin is ringed with mountains.  As you head south down the High Sierras and the Coastal Range mountains from Northern California, when you get to the northern part of the greater Los Angeles area, the San Andreas Fault which created those mountains makes a sharp left turn and the mountains change from being north/south to being east/ west.  They go quite a ways east and then again in Orange County turn a little bit to the south.

These mountains are some of the fastest-growing mountains in the world as they are continually pushed up by the action of the tectonic plates pushing against each other.  They are also some of the fastest eroding mountains in the world because they are made of a type of granite that, when shaken by the action of the San Andreas Fault (both big and little earthquakes), they begin to crack up, falling into little grains of sand as well as boulders of all shapes and sizes.

So now your big plate of desert is ringed with mountains running from east to west on the north side turning to the south on the east side and surrounded by water on the west and south sides.  That is the Los Angeles basin as it goes from sea level all the way up to almost 11,500 feet at the top of San Gorgonio Mountain on the northeast side of the Los Angeles basin.  West from San Gorgonio is the famous Mount Wilson Observatory at over 5,000 feet above Pasadena.  There are low foothills below the tall mountains, but the land rises quickly from downtown Los Angeles at only 330 feet above sea level to over 4,000 feet and up just about a dozen miles due north of Los Angeles.

While there are some beautiful trees and forests, most of what is known as the Angeles National Forest is not covered with tall trees that most people think of as a forest.  It is rather covered with what is referred to as high chaparral, a collection of thick scrub brush including manzanita, sumac, scrub oaks and other fun low-lying plants like poison ivy!  There are some bear, mountain lions, coyote, raccoons, squirrels and even the Western diamondback rattlesnake.  Encounters with these animals, especially the larger or more dangerous ones, are fairly rare considering the number of people who live in the basin below.

That desert we’ve been talking about had enough water to support some civilization, but less than 150 years after the founding of Los Angeles, vast amounts of water needed to be brought in from Northern California and the Colorado River to support the ever increasing population growth of the area.  Because there was so much land, once there was enough water, low usually single-story housing began to spread rapidly out in all directions from downtown Los Angeles, all the way up into the very edges of the forest with the highest homes in La Canada at about 2,400 feet of elevation.

People who visit always ask how far the city of Los Angeles spreads and how many people live there.  The answer you really want to know is that the city itself is long and narrow, stretching from the harbor all the way up to the mountains in some areas.  There are many cities and unincorporated areas of the giant Los Angeles County.  In 2005 the official estimate of the population of the Los Angeles metropolitan area was almost 13,000,000 people, while the larger five-county region was estimated to be over 17 million.  As more and more people moved in, they tucked houses into every little nook and cranny, valley, culvert, hillside, cliff, and available postage stamp sized beachfront lot.  Sometimes not paying much attention to the “lay of the land” where they were building or even the types of materials they were using.

You can’t really blame them.  It’s a beautiful place.  The scenery is gorgeous in all directions (I’m not just talking about the beautiful people).  When Rusty travels to Russia and is asked to talk about where he lives, he starts out by saying there are many days you can go surfing in the morning, drive a couple hours, and snow ski in the afternoon!  You can also drive a couple of hours from just about anywhere in the Los Angeles basin through the pass into Palm Springs and the warm desert which is usually sunny and pleasant even when the weather turns a little chilly by Los Angeles standards.  (Rusty would tell you what a little chilly is by Los Angeles standards but folks in the north and east would say that was mean.)

Where there are no houses or buildings in this big, built-up desert there are plants, lawns, trees and bushes of all shapes and sizes that make the desert look green and pretty.  You can walk along a cliff in Laguna Beach or Pacific Palisades and look over a landscaped lawn and garden to the blue Pacific Ocean and on a clear day see the island of Catalina and others just offshore.  It sounds like paradise…  And in many ways it is.  But in the second part of this series you’re going to learn some secrets that most people Rusty talks to don’t know.

Those secrets have to do with the dark side of living in this paradise:  special “changing” properties of those mountains; when the very air we breathe turns mean and how the life-giving water, without which Los Angeles could not exist in its present form, is sometimes its worst enemy.  You’ll find out the irony of calling an organization “Los Angeles County Flood Control”, why they build dams that leak, and why some people laugh and some people die in the infamous LA River.  You’ll find out just how scared officials are and why the whole area is awake all night long!  It’s all coming up in parts two and three of the Adventures of Rusty Waters, The Truth about the Great 2010 La Canada Mud Flood!