Lake folks often get into lively discussions over what the lake used to be like...more plants, fewer plants, clear water, murky water... Is there any way to really know for sure? Well, the answer is yes! In fact we can have a good idea of what lakes used to be like hundreds of years ago with a science called Paleolimnology.

Paleolimnology, sometimes referred to as "History in the Mucking," is the interpretation of past conditions and processes in lake basins. Each year since their formation, a steady rain of sediments, plant pieces, creature parts and other materials settle to the bottom of our lakes leaving a record of past conditions. Over the eons this fascinating record has remained safe and sound in the sediments waiting for someone who could unlock its secrets. In addition to providing background information on a lake, the sediments hold a record of natural and human disturbances that have occurred in the lake. The response of the lake to these disturbances provides insight into how the lake functions, and provides a better understanding of the significance of trends observed with modern monitoring programs.

Cores are typically dated by analyzing a series of samples from the surface to a core depth that corresponds with 200 years ago. The most common dating technique for sediments deposited within the last 200 years is the lead-210 technique. Lead-210 is a naturally occuring atom that exhibits radioactivity. It enters lakes primarily through precipitation and dry deposition (i.e. dust), following the decay of an atmospheric gas called radon-222 (radon gas).

Several methods can be used to corroborate the lead-210 dating technique. Testing of atomic weapons has left stratigraphic markers (layers) in the sediments of all lakes around the world. These markers include cesium-137 (a byproduct of atmospheric nuclear testing). Atmospheric testing by the U.S.S.R. peaked in 1963. It then dramatically declined after the implementation of the Nuclear Test Ban Treaty that same year.

In southern Wisconsin another marker that is often used to confirm sediment dates is arsenic (yes, arsenic). Sodium arsenite was used during the 1950s-60s in a number of Wisconsin lakes to control aquatic plants. Records are available that document how much was applied (Lake Tides Vol. 31, No. 2, 2006). The peak in arsenic concentration in the core corresponds with the time of maximum application.

Another dating marker that can be traced in lake sediments is stable lead. It was used in leaded gasoline until its removal in the mid-1970s and provides another time marker to check on the lead-210 dating technique.

Other fossils that are deposited and are useful for re-creating past environments are aquatic insect larvae and zooplankton. Insect larvae can be used to track changes in a lake’s oxygen content over time. Zooplankton are often eaten by fish and invertebrates, so changes in their numbers allow us to infer past fish populations. For example, a decline in large zooplankton is an indication of an increase in plankton-eating fish such as perch or bluegills.

We often get phone calls and emails from Lake Tides readers with a variety of questions about lake districts. Do you have a question about lake districts that you would like to see answered in Lake Tides? Send it to uwexlakes@uwsp.edu so we can include it in a future issue.

To comply with Wisconsin’s open meetings law requirements, a lake district should also:

• post the meeting notice at least 24 hours in advance in three locations likely to be seen by the general public. As an alternative, a lake district may give notice by paid publication in the local newspaper (this covers #2).

• provide the local newspaper with a meeting notice.

• give a meeting notice to any additional media source that has requested to be notified.

For more information on Wisconsin open meetings law requirements, see the Attorney General’s Open Meetings Law Compliance Guide found at www.doj.state.wi.us.

For more information on lake districts, see People of the Lakes: A Guide for Wisconsin Lake Organizations, www.uwsp.edu/cnr/uwexlakes/districts.

*Tax rolls are available to help lake districts generate accurate mailing lists for property owners. Mailing lists for electors (resident voters) are not always readily available, therefore, lake districts have the option of publishing the notice to get the word out to electors.

Our nation’s lakes will be undergoing a check-up in 2007 as the Environmental Protection Agency (EPA) initiates a statistical survey. The goal of the survey is to discover what percentages of the nation’s lakes are in good, fair or poor condition. A "stress test" will also be performed to examine the relative importance of nutrients, non-native species, lakeshore development, pathogens and other stressors on lake conditions.

The EPA’s approach is multi-faceted, and designed to strengthen state, tribal and interstate monitoring programs. This will encourage more efficient use of resources, expanded accessibility and better use of data, and partnerships among agencies and others. The survey should also set a sound baseline of data by providing documented information on the extent of water quality problems and key stressors on our nation’s lakes.

A total of 909 lakes, representing five size classes and distributed relatively evenly across the lower 48 states, are included in the survey. The lakes were selected randomly (excluding the Great Lakes) from a sample that includes freshwater lakes (natural and man-made) and ponds and reservoirs that are at least one meter deep (3.28 feet) and over 10 acres (4 hectares). A second set of samples will be conducted from 91 of the lakes. These lakes are a subset of lakes from the EPA’s National Eutrophication Survey (NES) that was conducted in 1972. Surveying these 91 lakes will allow other potential trends in water quality to be examined.

Wisconsin has 29 lakes included in the survey, ranging in size from 11-acre (4.6 hectares) Buckskin Lake in Florence County to 133,404-acre (53,989 hectares) Lake Winnebago. Two of the lakes, Blueberry Lake in Sawyer County and Haskell Lake in Vilas County, are located within tribal jurisdictions. Several of the lakes already have ongoing monitoring through citizen monitoring or other efforts, and that information will be used to supplement the national lakes survey data and provide background data for interpretation.

The EPA is providing funding and in-kind services to support the field and laboratory work needed to complete the survey. A team of Wisconsin Department of Natural Resources (WDNR) and U.S. Geological Survey staff will be sampling the selected lakes during a mid-summer sampling window. Samples to be collected include standard water quality constituents (nutrients, pH, color, chlorophyll a, etc.), water clarity, physical profiles, phytoplankton and zooplankton, a sediment core, algal toxins, pathogens, and benthos (lake-bottom organisms). In addition, a comprehensive shoreline assessment will be performed at 10 sites around each lake. These core indicators will be examined to diagnose the lake’s water quality, ecological integrity, and recreational value.

The WDNR staff has been actively involved in refining the sampling design, selecting metrics, reviewing field and laboratory protocols, conducting site reconnaissance, and communicating with other states on plans for the survey. The WDNR is planning to use the national lake survey effort to complement and enhance its own lake monitoring and assessment efforts in Wisconsin. For example, WDNR may add more lakes to better report on lake conditions representative of the full range of Wisconsin lake types. The WDNR may also collect additional data, such as detailed aquatic plant information or enhanced littoral and shoreland habitat parameters.

Results of the national survey of lakes will be analyzed and compiled during 2008, with a final report issued in 2009. For more information on the survey of the nation’s lakes, visit www.epa.gov/owow/lakes/lakessurvey.

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Calendar

February 21, 2007 – Conservation Lobby Day. Talk with your state Assembly Representative and your state Senator about why lake stewardship is important to you. For more information: www.conservationvoters.org/Public/index.php

February 24, 2007 – Regional conference "From Plan into Practice: Solutions for our Changing Lakes." Richard T. Anderson Education Center, Waukesha County Technical College, Pewaukee. For more information: www.wisconsinlakes.org/Events/07planintopractice.htm

Mar 1-2, 2007 – American Water Resources Association (AWRA) 2007 Meeting, Wisconsin Dells. "The Future of Wisconsin’s Water Resources: Science and Policy."
For more information: www.awra.org/state/wisconsin

March 3-5, 2007 – Midwest Aquatic Plant Management Society Annual Conference. Wyndham Hotel in Downtown Milwaukee.
For more information: www.mapms.org/MAPMSConf2007.html

March 26, 2007 – Early bird deadline for the 2007 Wisconsin Lakes Convention.
For more information: www.uwsp.edu/cnr/uwexlakes/conventions

Apr 21-22, 2007 – Lake Home and Cabin Show, Milwaukee. For more information: www.lakehomeandcabinshow.com/wisc

May 1, 2007 – Grants Deadlines.
Lake Protection and Lake Classification Grants

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Reflections