My guess is eminent domain will come into play for land along the fence line. There is an eminent domain bill on the governor’s desk awaiting his signature now that will bring land owners more rights in the takings process.
Been there, seen where an average example of the fence would go, it is IBWC land that does not belong to the farmers anyway and the "wildlife" most affected will be the border "coyotes." No one needs access to the actual river. The water from the river is NOT bailed out by hand as the enviro-wacks would have it appear, it is pumped out via underground pipe systems and in many locations in Texas it would help keep out the tick infested mexican cattle.
And if there is an area that requires a fence the only "recreation" going on around there is stemming from the drug smugglers.
In short, they are full of it.