” Then all that should be needed is a phone call from someone in Congress to the EPA, telling them that this practice is to cease immediately.”
I think you’re misunderstanding the role and structure of Congress. Conress acts as a whole, by passing laws (and confirming nominees, etc). In this case, Congress passed certain environmental laws. Absent any Constitutional or statutory prohibition, the Executive branch has broad discretion regarding the tools & techniques they use to enforce the law. The EPA, which is the agency designated to enforce the laws in question, has decided to use drones as one of their investagatory/enforcement tools. That is well within the Executive branch’s discretion. If Congress wants to prohibit the EPA from using this technique, Congress must pass a law prohibitng the EPa from doing so. A phone call from someone in Congress wouldn’t (and shouldn’t) work, because for every member of Congress who called the EPA to tell them to stop using drones, another member of Congress may call the EPA to tell them to continue using drones.