San Francisco’s Mountain Lake was recently poisoned to kill off any non-native fish. Turns out, there were a ton of them. The final death tally included over 850 carp, two catfish and many bass — none of them native to the spot.

The Presidio Trust isn’t blind to how the fish ended up there in the first place. As long as people buy fish as pets, some will end up in toilets, lakes and ponds.

So in order to keep Mountain Lake free of non-native species in the future, an “amnesty pond” will be set up for fish dumpers.

The amnesty pond will be located near Mountain Lake to deter dumpers from contaminating the lake, which will soon be repopulated with three-spined sticklebacks, Western pond turtles and chorus frogs. Hopefully it’s well-marked — it’s going to be tough to get people to stop using the big watery dumping ground over a smaller goldfish-friendly pond.

(Full disclosure: I once dumped a goldfish into the creek behind my grandma’s house. The other goldfish in the bowl died mysterious deaths, and I hoped to give the last fish standing a life of freedom. I’m assuming it died immediately because it was bred to live in a bowl, not a creek, but I like to imagine it became a giant man-sized goldfish that haunts the backwaters of Northern California to this day.)

The Presidio Trust plans on spending $12 million to restore Mountain Lake to the way it was before Europeans arrived in America. It’s the first-ever project of its kind.