Tenneson's arrest at the end. He obviously deserves it and then some, but what are the charges? It seems unlikely that Dr Dowd risked publicly exposing the creatures by reporting him for their attempted genocide. Did he turn state's evidence and report him for other transgressions, or are the horned lizards really that big a deal?
Yes. The EPA really doesn't mess around when it comes to the habitats of endangered species, although the effect could have just as easily been achieved with the revelation of Creech and his species existence.
There's also the whole "Poison The Groundwater" thing that they were trying to do to kill Creech's species, which would have long-lasting ecological consequences given that this was a farming community, and no doubt got a lot of water from wells that drew from said groundwater. Poisoning the groundwater could have serious consequences for both the people, their livestock, and their crops. Even if the EPA didn't come down on Tenneson like the wrath of an angry god, that kind of reckless disregard for human lives and livelihoods would get him into no end of trouble once exposed.
To say nothing of the crimes Burke and his thugs committed against Tripp and the others - the local sheriff included - for trying to stop the poisoning on Tenneson's orders.
Anything to do with attempted genocide or poisoning the groundwater is unlikely, as that would expose Creech's species and leave them vulnerable to exploitation by other humans. So unless Dr Dowd can come up with another reason for the groundwater poisoning, it's probably the lizards.
How many other colonies of Creech's species have been wiped out by starvation when fossil fuel extraction took away their food supply, without any human even suspecting they were down there?
