There are a number of creeks that the trail crosses prior to coming to LRV. I'm not sure which one you're talking about.
However, if you refer to this blog post:
water-sources-of-san-jacinto-mountains, you can see the significant ones.
I've also got a map that has a lot (if not all) of the water sources in the SJ's plotted:
San Jacinto Water MapAssuming that you're taking the Deer Springs Trail from Idyllwild, I would bet on the following (in order):
Maranatha Spring: Possibly flowing but low flow.
Joyce Spring: Probably dry
Middle Fk Stone Cr: Probably dry
N Fk Stone Cr: Probably dry
Deer Springs Crossing: Probably dry
Flake Spring: Probably dry
Bed Springs Crossing: Almost certainly flowing. This is the best natural source anywhere in the San Jacinto high country.
Rock Spring: Possibly flowing but low flow if it is flowing.
Lilly Spring: Probably flowing but low flow and difficult to recover water from.
LRV Crossing: Probably dry
Owls Hooch Crossing: Probably dry
HJ