Desert Studies: Flooding concerns in the Victor Valley

Since we are facing a possible El Niño winter, I felt an exploration of possible flooding is in order. Remember, despite our semi-arid climate, running water is the greatest erosion agent on the desert. And more people die in flash flooding that from too little water or too much heat every year. The principal danger areas follow below.

The Mojave River, the existing riverbed is only about half a mile wide, but the historic flood plain is between two and three miles in width. The River seems to be “tamed,” mostly by the Mojave Forks Flood Control Dam near Deep Creek. But a lot of people have moved here since the dam was built in the late 1960s or early 1970s, and haven’t witnessed the Mojave River at flood stage, like I have. I will return to this issue at the end of the article.

The Oro Grande Wash is another flood prone area. The wash is in two parts, both draining off the foothills of the San Gabriel’s. I believe it’s between thirty and forty feet deep, and I know people who’ve seen it flooded to the top. Such a flood would isolate those people living between the two halves. From the Oak Hills/Phelan areas, the Oro Grande Wash runs some ten or twelve miles, crossing under Interstate 15 and flowing approximately north-east to Center Street in Victorville, where it enters a concrete flood control channel, which empties into the Mojave River somewhere downstream of the Upper Narrows. I know of a mobile home park somewhere near the Mariposa office of Southwest Gas that is cut in two by the Oro Grande Wash.

Another area of concern is the Antelope Valley Wash; better know as “Honda Valley.” I have never seen this one badly flooded, but its width and depth bear witness to the effects of running water. It drains out of the Summit Valley area, also into the Mojave River. Fortunately, this is also the boundary for the City of Hesperia, and not many people live there.

A branch forms the wash through the golf course area and it, too, illustrates the effects of running water. A lot of streets in Hesperia flood very badly in heavy rainfall and drain into this portion of the Antelope Valley Wash. Some portions of the wash are twenty to thirty feet deep and besides the golf course and country club, there are a lot of homes bordering it. People doubting the potential should consider the down-grade on Joshua Street, Buckthorn, Peach Avenue, and, especially “I” Avenue. Be prepared to move to higher ground if it floods.

I wonder if the Town of Apple Valley or the City of Victorville has warned residents of Jess Ranch and lower Spring Valley Lake of the imminent flooding danger. The “bluffs” on the west side of Spring Valley Lake and those bordering the lower Victor Valley College campus also mark the western flood plain of the Mojave River. Fortunately, Hesperia is on high ground and probably safe in a Mojave River flood.

The eastern flood plain boundary, however, is the hills below Kiowa Road in Apple Valley. When you descend the hill below the college on Bear Valley Road, you don’t get out of the historic flood plain until you ascend toward Kiowa Road. During the last big flood, the Jess Ranch area was nothing more than a turkey farm and the new developments below Kiowa Road were only alfalfa fields, and there wasn’t a lot of damage potential. Does the Town Of Apple Valley have an adequate warming system in case flooding occurs? And does Victorville (or San Bernardino County, since Spring Valley Lake is outside Victorville city limits) have a similar plan for Spring Valley Lake and Victor Valley College?

There is one other potential problem to address. I believe that at least the upstream area of the Mojave River to the Upper Narrows actually runs through a “graben,” or a down-fault area between elevated areas. The headwaters are split at the Forks, one east (Deep Creek) and one west, which itself splits into two: the east (Silverwood, formerly Cedar Springs, Miller Canyon, etc.), and the west portion (Summit Valley and the Las Flores are). And there is an earthquake fault, the Cleghorn Fault, which runs right beneath the dam and spillway at Silverwood, and crosses the San Andreas Rift Zone. If the Cleghorn Fault were to move, it could cause the dam to fail. When the San Andreas moves again (the “big one”), it will probably cause the Cleghorn Fault to move, also. Such an event could cause the Cedar Springs Dam at Silverwood to fail. Potentially, a one hundred-foot “tidal wave” could be unleashed down the Mojave River channel, inundating everything in its path upstream of the Upper Narrows. I hope all those people living in the potential flood zones are aware of the danger.

Well, we’ll see what the following El Nino fall, winter and spring brings. But be careful if it rains a lot, don’t drive through flooded roadways and risk getting carried away and drowned. Stay safe!