Its because they need to own the land so they could have the right to suck all of it dry! And its very apparent when you drive down HWY 395 and look at all of the "lakes" like Mono Lake or Owen's Lake. In the case of Mono Lake, the LADWP started diverting water out of the river that fed it in the early 1900s and the water level dropped like a rock. Conservation efforts in the 1970s and 1980s stopped them taking as much water as they liked, and now the lake is actually rising again, but its still below its natural level. What's amazing is that Mono Lake is roughly on the same line of longitude as San Francisco, but LA is taking its waters. In the case of Owen's Lake, its even worse. LA completely sucked it dry. It turned from a salt lake like Mono to a salt playa in the 1920s, and now it whips up alkali dust every time there is a wind storm. The people who lived around it complained so much from the dust 'pollution' that LA agreed to wet the soil a bit to prevent dust storms. In fact, one of our professors at Berkeley was part of the scientific study which showed how the wind patterns in the Owen's Valley made the dust storms so bad. She studies how the wind (air) flows over mountains and in mountain valleys. She said that the dry lake bed which was once Owen's Lake was the largest point source of dust in the western hemisphere! Could you believe that!? After the study was published, that's when LA decided to start wetting the soil. However, when we drove by Owen's Lake a couple weeks ago, during a crazy wind storm, we could see the dust storm for miles away!
An alkali dust storm on Owen's Lake
The wind was really ripping across the Owen's Valley and picking up a lot of salts and other minerals and dust that cover the now dry lake bed. The cloud formations show just how windy the valley was. The low clouds over the Sierras to the left are caused by condensation of moist air over the mountains. The air is moving very fast downwards into the valley where it dries up, and picks up a lot of dust. In fact, the winds can get so strong that they knock over semi trucks driving on Hwy 395! Then the wind flows back up over the White Mountains to the right, forming this huge front of clouds that runs parallel to the valley. These are the crazy winds that pick up all of the dust and create a hazard when it is windy.
Not only that, but you can't even camp in the Owen's Valley because LA owns it to take water from the Owen's River. Many natural hot springs pop up in that valley and the run off drains into the river, which is tapped by LA. Therefore, LA doesn't want any new hot tubs built which would interfere with their water supply (even though they wouldn't at all), nor campers who would just like to enjoy the pleasant scenery.