Missouri has a wealth of lakes available for public recreation that range from small community lakes that can be enjoyed best by canoe, to large impoundments that would take a life-time to explore. With all of these waterbodies available to us, the sad truth is most of us spend all of our time on one or two lakes. While most of us are limited in the lakes we explore, this was not the case for Kurt and Joe. Kurt and Joe work in the limnology laboratory at MU and were the field crew for the Statewide Lake Assessment Project during 2004. They spent their summer traveling around Missouri sampling 61 different lakes.

Statewide assessments began in 1978, and have occurred every year since 1989. During this time over 150 lakes have been monitored, with most of these lakes having been monitored for at least 6 years and the key lakes within the state being monitored for over 20 years. This has resulted in what may be the most complete, long-term study of lakes within an individual state. Through this effort we have gained a better understanding of lake water quality and the factors that influence it, as well as how water quality varies in the short (within summer) and long terms (year to year). The data generated through the Statewide Assessment helps the state meet Clean Water Act requirements for monitoring lake water quality, but more importantly, the knowledge helps agencies (DNR, MDC, local governments, etc.) identify problems and manage our lakes.

Lakes monitored as part of the Statewide Lake Assessment Project in 2004. State physiographic regions are labeled. Northwestern lakes are monitored in a separate project.

During this past summer, Kurt and Joe took 244 Secchi transparency readings (each lake was visited on 4 occasions). The results reflect how variable lake water quality can be within the state. The overall average Secchi reading for the 61 lakes was 45 inches with individual lakes ranging from a low of 16 ½ inches to a high of 254 inches (21 feet!) of water clarity. One quarter of the lakes had average Secchi readings less than 28 inches while clearest 25% of the lakes had readings greater than 70 inches.

pictured: Kurt

pictured: Joe

Past data have indicated regional differences in water clarity, and the 2004 data support this observation. The Osage Plains had an overall average Secchi of 26 inches, while the Ozark Highlands had an average of 67 inches. The Glacial Plains and Ozark Border regions were intermediate with averages of 37 and 48 inches, respectively. Regional differences are due to differences in geology (deep nutrient rich soils vs. thin rocky soils), topography (the steepness of the landscape influences the lake’s volume), and land cover within the lake’s watersheds (agricultural vs. forest).

Readers familiar with the Lakes of Missouri Volunteer Program might wonder if there will be a need for Kurt and Joe in the future as the LMVP continues to grow. While both programs generate similar data (Secchi, total phosphorus, total nitrogen, chlorophyll, and suspended solids) there are some important differences. The Statewide Assessment is able to equip the field crew with a temperature/dissolved oxygen meter that allows for a vertical profile of each lake. This information shows us how the lakes are stratified or layered during the summer. The field crew also has gear for taking water samples from different depths. Currently, equipment cost limits the volunteers to just sampling at the surface of the lake. Another difference between the programs is that the Statewide Assessment crew can and do take other measurements and samples while on the lakes (total number of parameters measured varies from year to year as different questions about lake ecology are addressed).

In the past, supplemental monitoring has included: processing of various chlorophyll filters to investigate the size structure of the algal population, dissolved nutrient analyses to monitor the phosphorus and nitrogen available for plant uptake, zooplankton sampling to describe community structure and monitor invasive species, comparison of Secchi readings with and without a view scope, bacteria sampling to gauge trophic state relations, testing of new field equipment, algal samples to determine community structure, light readings to explore the influences of turbidity, and a survey of algal toxins in our lakes. These supplemental samples have improved our understanding of Missouri’s complex lakes. While volunteers collect quality data, it would be impossible to equip and train them to do all of this supplemental sampling.

As the volunteer program continues to grow, it will contribute more and more to the data we use to gauge current conditions and long-term changes in our lakes. But if we, as a state, are going to continue to expand our understanding of lake ecology as well as monitor for new water quality problems, we will need to have people like Kurt and Joe in the future. And my guess is they will be happy to spend their summer visiting lakes across the state.
Over 25 years worth of Missouri Lake data have been collected by a single project coordinated by the University of Missouri's Limnology Laboratory

Dan Obrecht

Back to the Fall 2004 Water Line

Brought to you by the Lakes of Missouri Volunteer Program