Mother Nature is wreaking some havoc on Lake of the Ozarks this spring, but it's nothing to be too concerned about. Rapidly rising temperatures are behind some natural phenomena on the water this year, according to state officials.
Mother Nature is wreaking some havoc on Lake of the Ozarks this spring, but it’s nothing to be too concerned about. Rapidly rising temperatures are behind some natural phenomena on the water this year, according to state officials.
The extreme heat the area has been seeing recently is considered a main contributing factor to unofficial reports of green water as well as official reports of fish kills at Lake of the Ozarks in June. While rain storms Wednesday afternoon and evening cooled things down, the Lake area along with the rest of mid-Missouri had been seeing daily temperatures in the 90-degree F range and even 100 degrees or more at times with little precipitation, weather more common in the Missouri “dog days of summer’ in July and August.
On Wednesday, Greg Stoner confirmed reports of a fish kill on Lake of the Ozarks. Stoner is the Missouri Department of Conservation Fisheries Management Biologist for the Lake.
According to Stoner, the kill appears to be restricted to the lower Gravois and Glaize arms, and is due to low dissolved oxygen in the water. He attributed the water conditions to high water temperatures which, before the rain, were approaching 90 degrees.
Non-toxic algal blooms contributed to the fish kill. When a large volume of algae dies off, it causes the dissolved oxygen to dive, Stoner explained.
Anyone concerned about swimming safety might want to avoid areas of water where there are large volumes of dead fish, but other than that the water is fine. It’s not a pollution issue, he said.
The early-season heat appears to be behind reports in the last week of two of the Lake of the Ozarks looking a little more green than usual.
High temperatures, lots of light and little rain along with plenty of nutrients in the water may be causing algal blooms, but that doesn’t mean they are toxic blooms.
According to Stoner, algal blooms on the lower Gravois are fairly common each year during the summer.
Water quality concerns can always be sent to the Missouri Department of Natural Resources, but according to DNR Water Quality Monitoring Section Chief Lynn Milberg, green water is not necessarily harmful and is not an uncommon phenomenon, especially given the environmental conditions this spring.
A relatively dry spring, there has been less rain to flush out the lake and less discharge at Bagnell Dam which means less movement of the water. These factors combined with extreme heat for the time of year when there are lots of nutrients in the water can mean more algae on top of the water, she explained. That is not necessarily a “bloom.”
Heat, lots of light and nutrients can make algae growth increase especially in coves where the water may be shallower and sees less movement, says Milberg, but that does not necessarily mean it is a harmful bloom that is large enough to deplete oxygen to aquatic life. It would be more odd to see green water in the main channel where movement from all the boating actually inhibits algae growth, she added.
Large amounts of dead fish in the water — a fish kill — according to Milberg, can be a signifier that a toxic bloom is taking place, but fish kills can occur for a variety of reasons with multiple contributing factors.
Algal blooms are caused by excessive nitrogen and phosphorus in the water, causing algae growth to occur faster than aquatic ecosystems can handle. It is considered harmful only when it has “detrimental effects on aquatic ecosystems; or human, livestock or pet health,” according to DNR’s definitions.
Algae can impact food and habitat and decrease oxygen in the water when occurring in significant volumes. Algal blooms are harmful to people only if they produce elevated toxins and bacterial growth.
Blue-green algae, what is actually cyanobacteria not algae, would be of greater concern. According to DNR, this bacteria can multiply quickly under certain conditions and are one of the more concerning types of what people think of as algal blooms. Cyanobacteria is capable of producing toxins that can be harmful to humans and other animals.
While all algal blooms look different from one body of water to another because of so many varying conditions, regular algae is often a darker, more subtle green than cyanobacteria which can be a really bright green.
Without seeing the green water lake residents have been talking about, Milberg says she can’t say for sure the cause or what is is. In addition to algae, it could also be a spill of some kind or a dye trace.
With the amount of water circulating Lake of the Ozarks, though these issues typically dissipate fairly quickly.
Anyone concerned about a suspected algal bloom or other water quality issue on Lake of the Ozarks or another body of water in Missouri may report the issue to DNR at https://dnr.mo.gov/env/cyanobacteria.htm by filling out the Suspected Harmful Algal Bloom Notification Form or download their BloomWatch App. General environmental concerns, such as a trash dump or discarded tires in a stream, can be made at https://dnr.mo.gov/concern.htm. Fish kills or accidental release of pollutants and chemicals represent an environmental emergency. You may call DNR’s Environmental Response Spill Line at 573-634-2436 or call the Missouri Department of Health and Seniors Services’ Public Health Emergency Hotline at 800-392-0272.