Kosciusko County is a lake-lover's paradise - Not only does the county boast 100+ lakes, but it also is home to the largest natural lake in the state (Lake Wawasee at 3,200 acres) and the deepest natural lake in the state (Lake Tippecanoe at 122 feet). For years Winona Lake was home to the famous Christian summer camp where Billy Sunday preached, and Indiana's oldest sternwheel paddleboat, the Dixie, has been cruising Webster Lake for the past 80 years. Our lakes are not only beautiful, but they encompass much of our region's cultural history. This is just one of the many reasons that we work so hard to protect them for our children and grandchildren to enjoy. Protecting our lakes starts with understanding them better - to learn more about Kosciusko County's lakes, read some of the general lake ecology information below. Armed with a more complete understanding of how our lakes work, you can become someone who makes a difference in their future! If reading about our lakes makes you fired up to help protect them, check out our list of the top 10 things you can do to help keep our lakes and streams clean.
Our lakes are not isolated bodies of water. They are fed from a variety of sources - Some water comes to them directly from rain, snow, ditches and streams. Other water comes to them indirectly, flowing downhill over the surface of the land or through groundwater before making it to the lake. This water that comes indirectly has a huge impact on water quality, and the area of land that water flows over or through to get to a lake is called a watershed. Whether they know it or not, every single person lives in a watershed. The water that hits your backyard will eventually make its way to one of our lakes - so what it goes through before it gets to the lake is important! And water doesn't just stop moving once it gets into a lake - It usually leaves that lake too and continues moving on until it gets to one of the largest bodies of water - an ocean. For example, water might drain into Winona Lake, but once it leaves there it makes its way through ditches and creeks into the Tippecanoe River. The Tippecanoe river ends up in the Wabash River, which flows to the Ohio River. The Ohio eventually drains into the much larger Mississippi River. Once in the Mississippi, water from your own backyard is on its way to the Gulf of Mexico!
The way that land is used within a watershed determines, to a large extent, the water quality of the lake or stream it drains to. Sediments (soil that has been washed into the water), organic materials such as leaves and plants, nitrogen and phosphorus from fertilizers, toxic substances, bacteria and other contaminants can enter lakes and streams through pollution that comes from a specific location (like a pipe from a business) or from many locations - including water that flows over the land from cities, landfills and agricultural areas. So the actions we take on our lawns, in our driveways and on our streets affect not just those areas, but our lakes and streams as well. That is why it is so important that we are careful with how we treat the land around our homes and in our cities, not only along a lake or stream shoreline. If you are taking steps to protect water quality on your property, you are making a difference in the water quality of our lakes and streams no matter how far away from one you live!
Kosciusko County is part of the Glacial Lakes region of Indiana. This means that of all our lakes, most are natural lakes that were formed by activity from glaciers. As glaciers moved across the land, they formed lake basins in several ways. Sometimes they gouged holes in loose soil or soft bedrock which then filled up with water. In other places they left rocks and soil across stream beds, causing a natural reservoir. In some places they left behind buried chunks of ice that melted to leave basins filled with water. Any of these scenarios could create a glacial lake.
No! Many people think of lakes as static systems, but in reality they are alway changing - both throughout the seasons and over the long term. The weather in our region is temperate, which means that we have distinct seasons. This causes our lakes to have a seasonal pattern in water temperatures. In the spring, just after the ice melts, the water is cold and the temperature is nearly the same throughout the whole lake. At this time all of the water is the same density too. This is important because the more dense water is, the heavier it is. Since colder water is more dense, it will tend to sink to the bottom of the lake. When the water is all the same temperature and density, wind blowing across the lake lets the water mix easily and thoroughly - This is called seasonal lake turnover. After this turnover occurs in the spring, the air temperature rises. This causes the water at the surface of the lake to become warmer, but the water at the bottom remains cold. Since cold water is more dense than warm water, that colder water will stay at the bottom of the lake with the warmer water floating on top. Lakes that are deep enough usually end up forming three layers during the summer months. The top layer is the warmest surface water, which is usually fairly uniform in temperature. It's called the epilimnion.
Below the epilimnion is the middle layer, which is where the water temperature starts to decline. In this layer the tempurature decreases rapidly with depth until it reaches the bottom layer. This middle layer is called the metalimnion or sometimes the thermocline. Finally there is the bottom layer of the lake, which is the very cold and dense water. Because this water is so much colder and more dense than the rest of the water, it usually doesn't mix with the other layers. This cold bottom layer is called the hypolimnion
As the weather cools in the fall, the surface water cools downas well. As the water gets colder, it gets more dense. Eventually, the surface water and bottom water will approach the same temperature and density. At this point the wind can once again mix the water in the entire lake in what is called fall turnover. As winter begins, the water cools further until the surface water freezes over. Under the ice, most of the lake will be at approximately 4 degrees Celsius for the winter season until the spring comes and melts the ice, and the process begins again. (image courtesy of Encyclopedia Brittanica)
You learned about seasonal changes above, but lakes also undergo long term changes - They get old! As a lake gets older it begins to accumulate stuff like leaves, dirt, and other organic material at the bottom. Over time, this material builds up and slowly makes the lake shallower. A shallow lake allows more light to get into the water, which allows for increased plant growth and warmer temperatures throughout the whole lake. If there are more plants, then there is more plant material to accumulate at the bottom of the lake when those plants die. When plants and other organic materials decompose underwater, they suck oxygen out of the water and it becomes difficult for some of our more popular game fish species to survive. Given a long enough time, a lake can actually fill itself in completely and disappear. This aging process is totally normal and is called eutrophication. In some places it takes thousands of years, but in others it can happen very quickly. The following terms describe approximately how far along a lake is in this process.
Being at a particular point in this process does not necessarily make a lake "good" or "bad". Eutrophication is a natural process. However, this process, which naturally takes anywhere from hundreds to thousands of years, can be so accelerated by humans that the time it takes can be reduced to a matter of decades. This is called cultural eutrophication - Which is basically making lakes "old before their time". Cultural eutrophication is caused by land use practices around a lake, particularly those which contribute eroded soil that fills in lakes and nutrients like nitrogen and phosphorus that cause an overgrowth of plants in lakes. Taking care of our lakes involves slowing down the process of cultural eutrophication by careful evaluation and change of land use practices that contribute to it.
There is a ton of stuff in our lake water! You may not think much when you look at water, but there is a lot going on in there that is unseen - and some that we see way too much. When studying a lake, we are interested in a number of these seen and unseen things. These include ion concentrations, dissolved oxygen, pH, nutrients that cause plant growth (nitrogen and phosphorus), chlorophyll (an indicator of algae), and bacteria.
In most lakes, the critters in them live in distinct areas. These areas are called zones and have special names to describe them. The littoral zone is the area near the shore where the lake is typically shallow and light can penetrate all the way to the bottom. This allows lots of aquatic plants to grow. Littoral zones are typically home to lots of plants like cattails, lily pads, pickerelweed, cardinal flower, and coontail. You would also find turtles, frogs, mussels, wading birds, aquatic insects, and some fish. The limnetic zone is the area of open water where light is not able to penetrate all the way to the bottom of the lake. This zone is usually towards the middle part of the lake where the water is open, and you would not find many plants here. This zone would be home primarily to a variety of fish and some aquatic insect species. In the littoral zone, there is a special area called the euphotic zone, which is where light can penetrate to. The euphotic zone is where you would find algae growth in many lakes. Finally, the benthic zone is the bottom of the lake where there are often rich organic sediments and lots of invertebrates like worms and aquatic insects. Some organisms are able to move freely throughout these zones, such as fish, amphibians, turtles, and insects. Others, like plants, aquatic insects, and other invertebrates are restricted to certain areas, while still others such as zooplankton and algae ride wherever the water takes them.
Image courtesy of Water on the Web
For more detailed information on lake ecology, you can complete the Lake Ecology Primer.