We converted to a 250 gallon plastic tank after one of our neighbors found a skunk in his well cistern. Double blech! Easier to keep sealed. Hope it was just a stray incident.
Joke time: What are two mice doing in my cistern?
The back stroke?
Thomas Sowell: There are no solutions, just trade-offs.
HA! well we've been here for 8 years without issue. VL, love the dogs, are those yours? We have hunters of the kitty kind that will have access to downstairs to see if they can round up any more. We've had downstairs closed off for a few weeks while the stinky bodywork part is being done on my husband's project car (the smell comes in through the door to the garage and into the house), so the cats have not been down there.