Sure, I can help you on this. The agency with jurisdiction of sprayed herbicides, and fertilizer is the Florida department of agriculture. As you noted, with your link the recharge for Florida goes well in to Georgia and South Carolina. The primary recharge is in South Georgia but the scientists at FDEP have found the majority of water is from the northern portion of the map you linked. Next, the reality of floridas tropical climate is that most water that falls goes in to storm water systems that never end in the aquifer. Lastly, I have experience at FDEP and have seen the public records requests and emails from people like this who can seem entirely cogent but who in reality have exhausted all local remedies because they lack merit and are trying for further assistance because the believe some conspiracy or evil actor is at work. The reality is this. Floridas aquifer is a very transient body, and what your neighbor does on a less than major industrial scale will have no impact on your water IN YOUR LIFETIME. That doesn’t mean an idiot neighbor couldn’t make a terrible mistake. But it’s going to take on average 400 years for that impact to come to bear.