Storm Gordon may cause lake mixing. Water is still safe to drink.

Storm May Cause Lake to Mix, Resulting in Discolored Water – It’s Still Safe to Drink

LITTLE ROCK, AR – With Tropical Depression Gordon making its way to Arkansas, increased winds and rain may cause a “mixing” of Lake Maumelle.

This would stir up sediment from the bottom of the lake and could increase the levels of manganese in the raw water source, which ultimately might lead to a slight discoloration of water at the customer’s tap.

If Central Arkansas Water customers do see a discoloration in their water, it’s important to know that it is still safe to use and drink. CAW continually monitors water quality and stays in compliance with federal and state health regulations.

Natural lake turnovers occur in most lakes around fall each year. That is because over the summer lakes stratify when a warm layer of water forms at the top due to high temperatures, while a cold layer remains at the bottom. As fall season temperatures cause the top layer to cool, that layer sinks and the upper and lower layers turn over, or mix.

This process stirs up sediment and organics from the bottom of a lake and often produces an earthy taste and odor. That taste and odor may be noticeable to some customers while unnoticeable to others.
Lake Maumelle typically does not get cold enough to experience a turnover event. However, increased wind does cause the lake to mix throughout the year, which can result in the discoloration of the water, but usually does not result in the earthy taste and smell, said Director of Water Quality Randy Easley.

CAW’s other water source, Lake Winona, does get cold enough to experience a lake turnover. It usually occurs toward the end of October or early November.

While each lake primarily serves a specific treatment plant that delivers water to different areas, there is some blending of water within the distribution system.

In preparation of the storm and the possibility of a lake mixing that might cause water discoloration, CAW’s water production team has increased its sampling in order to be prepared to treat any high level of manganese with additional chemicals at the treatment plants. CAW also stores extra water in Jackson Reservoir, which can later be blended with discolored water to lessen the effect.

The most important thing for customers to know if they do notice discolored water is that the water remains safe to drink and use. There is no reduction in water quality with regard to health effects.

Customers with questions about this process may call 501.372.5161.

A storm produces lightning bolts over Lake Maumelle in this CAW file photo.

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