Just have to interject some math here because I have heard and seen wild numbers thrown around in this case and others.
$30,000-$40,000 a year when the toll fees were $2 (a car, a person, a?).
Take $35,000 as the average between the estimated values, divide it by 365 for days in year and then take that result and divide it by 2 (I am assuming $2 a person here) to figure out how many people per day average would have to go to the springs.
($35,000 / 365 ) / 2 = 48 people per day that go to the springs averaged out across the year.
To me this seems like an awfully big number especially since the colder months at the springs there are very few people from my experience.
Just some food for thought.