Kansas Water Science Center
Period of Project: 2000 to August, 2005
Lake Olathe, Olathe, Kansas, located in northeast Kansas, is an important recreational resource for the city of Olathe, providing boating and fishing throughout the year. The lake also serves as a drinking-water supply, contributing about 10 percent of the city's water needs, with the remaining supply coming from wells in the Kansas River alluvium near DeSoto, Kansas. The reservoir was built in 1956 in response to the increased sediment deposition occurring in an upstream lake, Cedar Lake. Following completion of Lake Olathe, Cedar Lake was removed from service as a water supply, but it still remains as a recreational lake.
Taste-and-odor occurrences in the drinking water obtained from Lake Olathe have happened periodically during the past 20 years. These occurrences are probably a result of algal blooms that occur during the fall of the year but also may be derived from algal conditions in the shallow water of Cedar Lake that is water discharged during storm runoff to Lake Olathe via Cedar Creek. In addition, increased residential and commercial development in the watershed have created sources of potential contaminants, especially nutrients, that can migrate by surface-water or ground-water flow to either Cedar Lake or Lake Olathe. Nutrients serve as a food source to algae and bacteria, but an increase in nutrient concentrations in water can shift the balance from stable algae and bacteria populations to an enriched environment that leads to algal blooms and a reduction in the dissolved oxygen concentration. This condition, known as eutrophication, causes many problems in lakes and reservoirs, from taste-and-odor occurrences in the water supply, to the reduction in fish populations, to the elimination of the water body as a resource to the community.
A monitoring station using an automated vertical profiling water-quality monitor that measure specific conductance, pH, water temperature, turbidity, dissolved oxygen, chlorophyll, and PAR (photosynthetically-active radiation) is installed at Lake Olathe. The water-quality monitor makes continuous measurements of water conditions and relays this information via satellite to the internet so that water-treatment managers can use the information to make adjustments to water-treatment operations at Lake Olathe.
Monitoring of the lake water quality will provide the city with information to evaluate the effectiveness of recommendations from the Lake Olathe Watershed Protection Citizen Advisory Baord's report.
Long-term monitoring of Lake Olathe will help assess watershed activities that affect the water quality of this important source of drinking water and recreation.
Photos of Interest
This study provides a comprehensive assessment for the city of Olathe with which to help manage development and water quality in the Lake Olathe watershed and reservoir. Historical changes in nutrient and sediment loads can be evaluated from the results of the bathymetric surveys and can be used to evaluate the effects of changes in land and chemical use in the watershed. Additionally, results of chemical analyses indicate whether there is cause for concern for selected organic compounds in the sediment that may bioaccumulate in the biota and cause human health concerns through the consumption of fish. Results of the study can be used by the city of Olathe to alter their supply source or treatment strategies using measured data for taste-and-odor problems. The measured changes in water quality will allow the city to provide improved drinking-water. Results from this study benefit Federal interest by developing tools and approaches that can be applied throughout the Nation for small watershed water-supply reservoirs and the effects of urbanization on these water bodies. Eutrophication of lakes and taste-and-odor problems are national problems that can be addressed through information on the watershed in addition to the use of engineering approaches. Results of this study have broad application in eastern Kansas and the Midwest where there are a large number of small impoundments with similar concerns and problems.