LAKE POTOMAC FISH KILL

On Friday afternoon July 24th an alert resident photographed dead fish on his shoreline and notified the Lakes Commission of a potential problem. Lake Potomac Commissioner Bob Blameuser was notified and reported back that the fish kill was serious. I notified McCloud Aquatic Services and the Lake County Health Department Lakes Management Unit leaving messages with both organizations. Saturday evening some village officials observed the problem. Saturday morning I also observed the fish kill and documented it with photographs that were immediately forwarded to McCloud and the LCHD LMU.

First thing this morning, Saturday July 27, Lyle Erickson from McCloud surveyed Lake Potomac and conferred his findings with Commissioner Blameuser, Village Administrator Matt Formica and myself. He was asked to forward a note documenting his findings. The text of which of that note received at 4:00pm this afternoon is quoted below:

"Ken

The inspection of Potomac this morning revealed that the fish died from a bacterial bloom based on the following information.

I inspected Potomac on 7-23-09 with good water clarity, water temp. of 78.6, pH of 9.4, and oxygen reading of 11.3 ppm. The lake was treated for slight filamentous algae, with moderate Chara, Small Pondweed, and Water stargrass also present.

On Friday 7-24-09 Bob Blameuser reported "the water had an odd cloudiness to it that did not look like normal turbidity" This cloudiness is common with bacteria blooms.

On 7-27-09 another inspection was made. The water clarity was good, water temp. 77.5, pH 9.2, and oxygen readings ranging from 5.6 - 8.7 ppm. The majority of the dead fish noted were young of the year, with dead tadpoles showing lesions associated with a bacteria. The YOY (young of the year) and tadpoles are more susceptible to bacteria than other fish and frogs.

This season has been one of the worst seasons for bacteria problems due to the strange and wet spring and the cool temperatures we have been having this summer."

Lyle J. Erickson

Fisheries Biologist

Manager Aquatic Services

Additional comments made by Lyle this morning from his 25 years of experience and management of our lakes since 1995 included the following:

Bacterial infections occur rapidly and are over equally quickly. They are present at all times in the sediment and when conditions are just right there numbers greatly increase. This year has been unusual and apparently perfect for these bacterial outbreaks as evidenced by numerous occurrences all over the county. After leaving Lake Potomac he went to a lake in Naperville with the same problem.

His feeling is that while the fish population is greatly reduced from the winter kill and this bacterial kill, the numbers and size of fish indicate there should still be a remaining population of fish in the lake. How many remain only time will tell. The larger fish survive the bacterial infections better than smaller fish. Bluegill often rebound quickly spawning multiple times per year and may still spawn again this year. Remaining Largemouth Bass may grow large more rapidly than usually because there will be less competition for food.

Restocking may not be necessary. He will continue to watch the lake for indications of surviving fish. No catfish or muskies were observed among the dead fish along the shoreline.

If you are a Lake Potomac shoreline homeowner, boater or fisherman, please watch along your shoreline from time to time and let a Lakes Commissioner know if you see fish swimming of if you observe no live fish over the next days and weeks.

If you have questions, feel free to contact Bob Blameuser, Lake Potomac Commissioner or myself.