Mammoth Creek, once it's joined by a hot springs, is known as Hot Creek. That feeds into the Owens River, which doubtless you'll recall goes a lot of other places...including to LA.
It's not just the town of Mammoth Lakes that L.A. is keeping an eye on.
LADWP recently filed two lawsuits against the town, arguing that its rights to water from Mammoth Creek are senior to those of Mammoth Lakes.
Mixing it up with Mammoth in court might send a message to backwoods water thieves the LADWP fears are digging into supplies.
I interviewed Marty Adams of the L.A. Department of Water and Power about the legal disputes with Mammoth. I was surprised when he said that Mammoth wasn't the only potential usurper of water to which LA claims rights. Adams claims thieves are possibly diverting a lot of water from the creek under cover of darkness. Unlike Mammoth's water district, these guys don't apply to state regulators for rights. They just dig ditches and divert.
If all the water in a river or creek is appropriated, or devoted to a purpose, then it's probably illegal if someone comes along and diverts water for animals, crops or to make a pond on their property. In its present legal fights with Mammoth Lakes, LA claims that Mammoth Creek was fully appropriated to LA since 1905. L.A.'s been concerned with illegal diversions around Lake Mary and the Mammoth Creek system for a while now. (Monitoring water-jacking is one of the stated duties of the aqueduct keeper).
Adams' comments serve to underline that L.A.'s not necessarily looking to put Mammoth Lakes out of business. The LADWP's simply shoring up its assets against future loss, and will take legal action against those who infringe on them.
It's a romantic notion, the idea of water poaching. I've no doubt it's very real, but quantifying it seems incredibly difficult. Unless LADWP actually catches someone up there, it's rare that we water users down here can actually tell fact from fiction.