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Spring 2008 Newsletter SHALLOW LAKES   When most people think about the perfect lake, they imagine clear blue waters, sandy shorelines, and great fishing. Unfortunately, not all lakes are created equal. Shallow lakes in particular present a stark contrast to these images, but these lakes offer their own brand of natural beauty and value. HOW THEY'RE DIFFERENT There are many characteristics of shallow lakes that cause them to behave differently than deeper lakes. Whole books have been written about this, but here are a few of the key concepts:     1) They generally stay mixed from top to bottom throughout the summer.      2) They usually experience high levels of nutrients that fuel algae or plant growth.     3) They tend to persist in one of two states:                 • Plant-Dominated - dense plants / clear water                 • Algae-Dominated - lots of green algae / few plants Because of these characteristics, shallow lakes are often heavily managed in an attempt to make them more like deep, clear lakes. While some management activities can improve the recreational and ecological quality of shallow lakes, it is equally important to recognize that our expectations need to be managed as well.            Plant-Dominated State Algae-Dominated State     KEY POINTS Here is a list of decisions, expectations, and monitoring objectives that should be addressed by anyone interested in managing a shallow lake: What are the most popular uses for your lake, and how do plants or algae affect them? If you water-ski, you might not mind green water as long as there aren't dense plants. If you like to fish or hunt ducks, you may want to promote the establishment of more plants. If you just like to sit on the dock and soak up the view, you may want clear water and nice emergent plants rather than stinky green water. Remember, shallow lakes are generally one or the other, so you will most likely need to choose between lots of plants, and lots of algae. How much water and phosphorus flow into your lake? Many shallow lakes have accumulated phosphorus from inflowing runoff for many years. If the sources of this inflowing phosphorus are not reduced, there is little hope for improvement. Even if these sources are effectively shut off, it may take many years to use up all of the accumulated nutrients left in the lake sediments. Many shallow lakes are also affected by their "flushing rate" - which depends on the volume of water flowing through the lake in relation to the volume of the lake itself. Lakes that flush quickly may see clearer water during wet periods.  What is the phosphorus concentration in your lake's water? In general, the higher the phosphorus levels, the more likely it is that a shallow lake will tend to stay in the algae-dominated state. If you want to improve water quality, fishing, and aquatic plant growth, it will probably be necessary to reduce the phosphorus levels first. Are we trying to force a square peg into a round hole? Shallow lakes are complex systems with many mechanisms that resist our wishes to make them look deep and blue. In addition to working to manage the real issues surrounding many shallow lakes, we should also consider managing our expectations so we can enjoy these waters for what they are. A BEAUTY OF THEIR OWN Most shallow lakes will never look like the quintessential "up-north" lakes we all love. Even with unlimited funding and extensive technical know-how, shallow lakes will tend to be very nutrient-rich systems that support either lots of plants, or lots of algae. While this may be disheartening for some lake-lovers, these special lakes can provide food and habitat for rich assemblages of wildlife, spawning areas for fish in deeper connected lakes, and can offer a different kind of natural scenery that can be every bit as enjoyable as the classic "ideal lake". THANK YOU FOR YOUR INTEREST I have included additional resources below so you can continue learning about shallow lakes on your own. Thank you once again for your interest in Freshwater Scientific Services, LLC. Please feel free to forward this newsletter on to anyone else who might find it interesting. Sincerely, -James A. Johnson  Aquatic Ecologist  Freshwater Scientific Services, LLC  mail@freshwatersci.com SHALLOW LAKES RESOURCES MN Shallow Lakes Forum (March 27-28) MN Shallow Lakes Forum Information Recommended Reading on Shallow Lakes A Guide to the Restoration of Nutrient-Enriched Shallow Lakes Brian Moss - School of Biological Sciences, University of Liverpool with Jane Madgwick, and Geoffrey Phillips 1997 - W.W. Hawkes, UK (Hard to find, but worth the effort - try searching online)   Ecology of Shallow Lakes Marten Scheffer - Dept. of Env. Sciences, Wageningen University - Netherlands 2004 Paperback - Kluwer Academic Publishers (More of an advanced text-book, but loaded with good stuff - available on Amazon.com) Links to Online Resources for Shallow Lakes MN Department of Natural Resources - Shallow Lakes Program Case Study: Restoration of a large shallow Wisconsin lake

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