BLM stays are typically restricted to 14 days in any ~28-day period, after which the camper must relocate at least ~25 miles away. The Long Term Visitors areas allow longer stays in one place or in one area.
Because of the longer stays and greater density, LTVA often have supplementary rules.
LTVAs are:
… specially designated areas located on BLM lands in California and Arizona. These LTVAs provide places for visitors to stay for longer periods of time between September and April. A seasonal special recreation permit is required, and the permit allows visitors to stay in any of the six LTVAs in California or two LTVAs in Arizona1)
These areas are open for discounted use from September 15th through April 15th each year and do not have stay limitations. They generally provide dump stations, water, trash and toilets.
As of Jan 2017 the fees were:
The cost is $180.00 and is valid for up to 7 months. A Short Term Permit can be purchased for a 14-day stay. This permit is $40.00.
The 7-month pass works out to $0.86/day and the 14-day pass to $2.87/day, assuming one stays the whole duration.
Long-term permits are now available for camping within the Tuttle Creek, Goodale Creek, Horton Creek, and Pleasant Valley Pit campgrounds in Inyo County, and the Crowley Lake Campground in Mono County… A long-term permit also allows visitors to camp for up to 30 consecutive days in any of these campgrounds… The fee for a 30-day permit is $120. The fee for a 90-day permit is $320.5)