Force of Nature
When the Enterprise searches for the missing medical ship Fleming in the Hekaras Corridor - the only safe route through an area filled with tetryon particles - a Ferengi ship suddenly opens fire. DaiMon Prak claims that his ship has been disabled by a Federation buoy, and the Enterprise is attacked the same way only a few hours later. It turns out that Rabal and Serova, brother and sister from Hekaras, want to prevent all ships from engaging warp drive in the corridor, for they think warp drive destroys the fabric of space. Serova sacrifices herself by opening a subspace rift in which her ship is destroyed, thereby proving that their theory is correct. The Federation declares a general warp speed limit of Warp 5, to prevent further damage until a solution to the problem is found. summary by Ex Astris Scientia
Hm… environment protection.. One of my Trekkie friends actually wrote a story where this issue was being addressed permanently. I mean, not only one system but the whole Galaxy had to be protected for longer than just one episode. Consistency issues, eh? I’ve always believed that a LOT of fanfiction is much better than some of the original Star Trek…