Bishop BLM website gives status of Crowley Lakes campground:
"Crowley Lake Campground is now closed for reconstruction. This project will continue into 2012. The campground will open for fishing season opener and remain open until July 5th. It will then close to finish re-construction." Fishing season just opened, so I guess that camp is now open until July 5th. http://www.blm.gov/ca/st/en/fo/bishop/camping/index.html
Get the current status of Mammoth campgrounds from the Inyo NF website. They had a real bad windstorm about December 1; thousands of trees blew down. Cleanup continues. In a normal year, dry camping in the Mammoth area is wonderful. Many campgrounds to choose from. Dispersed (remote) camp areas seem to be getting more limited each year. Inyo NF camping info quick links
Most if not all of the old free camping areas are gone, I would do as SteveAE suggested and contact the inter agency for info. There were some areas on the Benton Road from Mono Lake to Benton but those too may be closed. We're big time now in Mammoth (accoring to the Town Council and Visitors Bur.) and prices are too. The Town is virtually bankrupt and prices for everything including camping in Mammoth will only go up. Crowley is owned by Los Angeles Dept. of Powerful Water and as soon as our Mayor figures out how he can do it, he will tax everything at Crowley too.
"I travel not to go anywhere, but to go. I travel for travel's sake. The great affair is to go". R. L. Stevenson