A few weeks ago, the question posed at the end of the FILA column was, “Does weather affect a lake’s water quality?” The answer was that yes weather is a factor. This led to some people wondering about some of the specifics concerning weather and the lake.
The Iowa Department of Natural Resources works diligently to monitor Iowa lakes, track nutrient reduction strategies, do watershed management and maintain water quality standards. These policies and plans aimed at water sources for drinking and recreation assist with water quality. But in studies done by agencies and non-profits there are weather occurrences that impact water negatively and positively and are totally under the control of Mother Nature.
According to studies done by Michigan Sea Grant, “Weather affects water temperature in a lake every day and throughout the year.” For example, “In the spring the sun begins to warm the cold water near a lake’s surface. When water reaches a certain temperature – 39.2 degrees F – it reaches its maximum density or heaviness and it sinks. This process causes a lake’s waters to mix. Winds get stronger during spring and help to mix the whole water column, from top to bottom. This seasonal mixing, called turnover, also occurs in the fall. This mixing helps circulate nutrients throughout the lake.”
If warmer temperatures persist in an area, it makes a difference on the chemical reactions that occur within a lake. “And these chemical reactions matter because they can result in the release of nutrients, potentially from the sediment, which can then go on to affect the rate of significant events in the lake, such as algae growth.” (International Institute for Sustainable Development -IISD)
Wind is a factor that increases oxygen in a lake which is a positive. Negatively when winds blow along the surface of the water, it creates friction. The stronger the wind blows, the greater the friction, and the greater the waves. Waves can increase the turbidity of the water, pulling currents and nutrients along with them. It is turbidity (the quality of being cloudy, opaque or thick with suspended matter) that has Five Island Lake still on the Iowa DNR’s Impaired Water list.
Another lake phenomena comes from reference.com. “Lakes, because they are large bodies of water, produce the most dramatic effects on surrounding climate. Water takes longer to heat and cool than land surfaces. This delay causes water to retain heat during the winter and remain at a lower temperature in the summer.”
Weather does have both negative and positive impacts on a lake.
Previous question’s answer: Five Island Lake’s shoreline is 12.5 miles long
Question: What was unique about the restoration of the shoreline below the railroad trestle in 1911-1920?
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