The SEAT program is by and large a BLM program. The USFS does utilize SEAT aircraft on fires, but it's really mostly all BLM. Some state contracts...but mostly BLM.
That said, if the State of Oklahoma wants SEAT aircraft to fight fire on State lands, the State of Oklahoma needs to contract SEAT aircraft. Why aren't there aircraft under contract in Oklahoma? Nobody has offered the contract.
Much of the fire taking place in Texas and Oklahoma isn't on BLM land. Or USFS land. A lot on State, and private land...the government doesn't arbitrarily offer to pay for firefighting services on other lands. A lot of people don't realize this. Get an airtanker to drop on your private land, and you may have to foot the bill for the drop. USFS uses BLM assets on USFS lands, and the BLM bills the USFS. BIA uses DoD helicopters, BIA pays DoD. Just like Customer A using the services of Professional B.
Fire assets aren't merely floating around out there as charity services...someone somewhere has to pay to make it happen. SEATs sit in several locations around Idaho, for example, because the State of Idaho has taken the initiative to contract the aircraft. When the aircraft fly on a USFS fire, the State gets USFS funds to offset their costs or cover them. When the aircraft flies on a local fire on State, county, or city lands, the State is then left to negotiate with whatever municipality or agency owns the lands to work out the funding. In times of an emergency burn in which federal emergency funds become available, FEMA and other sources come into play, and then resources become a lot more open and available.
Tanker aircraft are very expensive. In light of what they can prevent and save, it's a heck of a bargain, especially when considering what's saved in dollars from preventing the fire from turning into something else...millions and millions of dollars. However, regardless of the economy, someone, somewhere has to pay for these assets...they're still expensive to own and operate. You see concentrations of tankers in places where the contracting agencies have the largest amount of lands, greatest concentrations of fuels, etc.
In the late 90's, we started seeing some record large fires in Florida. We went down in Large Air Tankers, and worked very hard, but also often sat and watched the fire burn...the State agencies didn't have any clue how to use fixed wing assets. Over the course of several years, we started seeing a lot more use, and now fixed wing assets do contract in Florida. We see fixed wing assets contracted in a number of states, often by various State departments of natural resources, and other various offices. Minnesota, for example, had a PB4Y-2 under contract, and we lost that when they got their own CL-215's.
California has it's own literal firefighting air force, flying OV-10's for observation, command, and control (air attack), and Grumman S-2T's. When the large air tanker fleet was effectively "grounded" (contracts cancelled; the LAT program wasn't grounded) recently for a time, the State of Oregon had the foresight to contract large air tankers independently and go head to head against the USFS over the issue.
If the State of Oklahoma or State of Texas wants aircraft on contract, the State will probably need to contract the aircraft directly. Presently, SEAT aircraft do have contracts down there, though a lot of folks aren't aware. Little Rock, AR, has had a LAT contract for many years, now. And during times of fire activity, LAT and SEAT aircraft, as well as Lead aircraft and helicopters, and air attacks, have been sent to and worked out of Texas and Oklahoma as long as necessary. We've had pilots die on fires down there...so yes, the assets are available and do work there...the direct availability is largely the responsibility of the agencies that will be using them, and if these are State agencies, then it's a State matter.
