Just when you thought it was safe to go back in the water. Looking to get in on the campy “Sharknado” phenomenon, Animal Planet has set its own horror film from The Asylum — the same people behind “Sharknado” — called “Blood Lake: Attack of the Killer Lampreys,” set to premiere this Memorial Day weekend.

The two-hour scripted movie stars Shannen Doherty (“Beverly Hills, 90210”), Christopher Lloyd (“Back to the Future”) and Jason Brooks (“Days of Our Lives”), who battle the lampreys — eel-like fish with huge teeth and funnel-shaped mouths — after they slide their way into the city’s sewer system and start terrorizing the residents of a small Michigan town.

Doherty in “Blood Lake.”Photo: Animal Planet

Brooks plays Mike, a fish and wildlife expert who moves to the town with his wife, Cate (Doherty), after being summoned by the town mayor, Akerman (Lloyd), to help deal with its attacking fish problem.

(“River Monsters” star Jeremy Wade also makes a cameo.)

But with these blood-suckers on the loose, the town’s residents quickly learn that a casual dip in the pool or routine trip to the toilet can turn deadly as the lampreys hunt for their next victim.

As the logline states, “There is absolutely nowhere to run, and no one is safe.” Cue the green-screen effects and overly dramatic score.

“Blood Lake” will premiere on Sunday, May 25 at 9 p.m. as part of the network’s third annual “Monster Week” (actually nine days long) programming block.

Other Monster Week specials include “Man-Eating Zombie Cats” — about big cats with a thirst for human blood — and a quest to find a giant crocodile tormenting a village in “Nature’s Most Wanted.”