As the President of the Forest Cemetery Association, I would like to address your readers' concerns about the green material currently covering much of our ponds. It isn't algae (which was have successfully treated, at considerable expense, with applications of copper sulfate at three day intervals).
What you see now is a layer of tiny aquatic plants called duckweed. Since a single plant can multiply 17,500 times in a two-week period, it spread over both ponds very rapidly.
While extremely unsightly, I want to assure you it isn't harmful to the swans or other waterfowl and it even makes up part of their diet. The large number of Canadian geese who arrive at Forest Cemetery during a stopover on their annual migration will also consume a portion before continuing their flight.
Mark Walker, our Groundskeeper, talked to an aquatic specialist about the duckweed problem and learned control depends on several things. Older ponds and those where the water is calm and not aerated, like ours, are more susceptivle. He reported spraying would be of no value, but use of a blue dye, made of food coloring, added to the ponds beginning in the spring would help block the sunlight. This will aid in nutrient reduction that duckweed feeds on. Use of this product would reduce the growth of duckweed and still be harmless to animals and wildlife.
One of the most important means of control is having a healthy fish population. Later this fall we plan to re-stock the ponds with the appropriate number and species of fish, such as grass carp, which are known to feed on duckweed. Unfortunately our ponds have been totally depleted by individuals who use drag nets to catch bait and also dispose of any larger fish they happen to catch. Due to this problem, we have requested that the Oskaloosa Police regularly drive through the cemetery at night to help end illegal fishing.
As a long term solution to improve the appearance of the ponds for years to come, we are exploring a dredging operation as the depth of the water has diminshed from silting in. Deeper water will also help in maintaining a fish population. We plan to get electricity available at the ponds so aeration can be done as that helps greatly in controlling algae and other growth.
We strive to maintain the appearance and beauty of Forest Cemetery and preserve the grounds as a final resting place for generations to come.
Gordon Anderson, Oskaloosa