Record heat during the summer months has created the warmest lake and pond water we’ve seen this early in the season.

Lakes and ponds are suffering right now!

We have already had to clean up fish kills in several locations. Hot water simply cannot hold as much dissolved oxygen, and oxygen demand in a hot pond is much greater. Extreme conditions have contributed to some desirable plankton populations crashing while undesirable cyanobacteria (formerly called blue-green algae) populations bloom. We sometimes need to postpone algae and aquatic weed control efforts so we don't further reduce dissolved oxygen concentrations in such hot water.

Hot water is very stressful on fish!

There are many stressors affecting fish health, but the majority of stress is caused by depleted oxygen in the lake and pond water. Water has a limited ability to absorb and hold dissolved oxygen. That ability diminishes as the water temperature rises. For example, water is saturated with dissolved oxygen when it contains about 13 parts per million (ppm) - also expressed as milligrams of oxygen gas per liter of water, when the water temperature is 41 degrees Fahrenheit. That same water is saturated and cannot hold any more when it contains 7 ppm if the water temperature is 95 degrees Fahrenheit. Furthermore, fish and all the microorganisms living in a lake or pond require twice the amount of dissolved oxygen from warm water to survive because their metabolism increases directly with water temperature. Another problem is decomposing organic matter which also consumes almost twice the dissolved oxygen for each 15 degree increase in water temperature. 

How to tell if your lake is unhealthy

When you visit your lake or pond, pay attention to the water color. Brown, red or intensely green water may indicate a problem. How deep into the water can you see? If you can't see deeper than 12 inches, problems may be developing. Are tiny specks suspended throughout the water column? Notice if a surface film is present. That may be cyanobacteria (that blue-green algae) and can lead to problems. The extent and type of floating vegetation is also important. Is there a strong musty odor? Look for fish swimming sluggishly near the surface or gasping along the shoreline, particularly early in the morning. Dissolved oxygen is usually lowest just before dawn because lakes and ponds naturally consume oxygen during darkness and produce it during the day. These are some of the tell-tale signs that your lake or pond is unhealthy.

Benefit of fountains & Aerators in Healthy Lakes and Ponds
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One of the best things you can do is install a type of aeration device to increase dissolved oxygen and water circulation in the lake or pond. Fountains act as excellent propellers to circulate the water around the lake and into the air. Not to mention, they are pleasing to look at and they muffle nearby noises. Fountains provide a safe haven of aerated water near the unit and will usually prevent fish kills. During the summer make sure to run the fountain 23 hours per day - this may seem too long but this will prevent the problems likely to occur with increasing water temperatures.

Another option is diffused air systems, often called “bubblers” that cost much less to purchase and operate than fountains. Bubblers circulate water so effectively, it is crucial to follow start-up instructions to avoid depleting the thin surface layer of oxygen rich water. In addition to diffused air systems, various mechanical water circulators are available. The best type of aeration system for you should be based upon the size, shape and depth of your lake or pond and the power supply present. You will also have to determine your objectives and how much money you are willing to spend.

Emergency aeration is an option if necessary. We have a few emergency aerators that are available for rent. We also have a couple of generators that can provide electricity to the aerators if no power is available near the lake or pond. Spraying water from a hose may be sufficient. Aim the hose parallel to the shoreline so the water spray encourages the pond surface to circulate.

Using a boat motor to circulate the water is not the most efficient solution, but as a last resort it will suffice. If using this method it is better to  keep the boat stationary while the motor runs rather than driving across the lake or pond. Ideally, this method among the others need to be deployed before your fish start dying. Fish are a significant investment in a lake or pond. Many have grown large through feeding, population management and tender loving care. No one wants them to die. And believe me, no one wants to clean up a fish kill!

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