Pond turns over; fish go belly up

    What does it mean for a pond to turn over? Many in Holyoke had the unfortunate opportunity to learn last week when that phenomenon happened at the Lions Club Fishin’ Hole just east of town.
    Normally water in a pond is stratified, with cold, dense water at the bottom and lighter water at the top, where it is warmed by the sun. Water at the bottom of the pond has very little oxygen. Turnover happens when different levels mix due to a change in the temperature of the water at the surface. The resulting mixture can be too low in oxygen to sustain life.
    Turnover can happen when the seasons change or, as Holyoke found out, when a storm hits. Last Monday night, July 16, a storm passed through and the high winds resulted in a rapid turnover and the death of many of the fish in Holyoke’s pond.
    More than a few people taking walks in the area were met with the ghastly sight of floating fish, and the appropriate authorities were notified.
    Holyoke Lions Club member Larry Stein said that the pond typically turns over about three times each year, but it’s more gradual so there aren’t such dramatic side effects.
    District Wildlife Manager Kyle Gordon explained that such turnovers are common in shallow ponds, such as Holyoke’s, and that nature will have to take its course. Between the remaining fish, turtles, raccoons and other scavengers, the dead fish will be consumed and simply become part of the pond.
    In order to help restore oxygen levels to where they need to be, Holyoke Lions Club has kept the aerator running 24 hours a day, rather than the 12 it usually runs.
    Next year, when the time comes to restock the pond with catfish, green sunfish, bluegills, bass and crappies, Colorado Parks and Wildlife will determine how many extra fish will be necessary to get the pond back to normal. In the meantime, the pond may smell a bit fishy, but it’s nothing to be worried about.