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Lakes Health

Directed Lake Surveys

Monitoring Objectives

The objective of directed lake surveys is to strategically collect holistic lake information needed for assessment (303d reporting) and lake management needs on a two-year planning cycle. The focus of this work is to collect biological, physical, and chemical data on lakes with a statewide perspective, but also to address local lake management issues including: aquatic plant management, shoreland zoning, high capacity wells, lake restoration projects, dam regulations, and blue green algae blooms. Lakes shall be selected both for protection and restoration.

Monitoring Design

Lakes will be selected on a 2-year cycle by regional biologists and the statewide lake monitoring coordinator to balance local and statewide needs. For assessment purposes, lakes are prioritized if trophic status indicators (from satellite imagery or initial water chemistry) suggest impairment but data for impairment listings are insufficient. Lakes are revisited to obtain sufficient data for listing purposes. Soon aquatic plants will routinely be surveyed on follow-up monitoring lakes, but currently only water chemistry samples are taken. All lakes targeted for lake management purposes must have public access. Specific management objectives determine which lakes are targeted and which parameters are monitored (see table below). The most prevalent management needs vary across the state. Therefore, allocation of resources to monitoring objectives varies by DNR region. Lakes are further prioritized for monitoring if they are on the fisheries management monitoring rotation, if they are being monitored for AIS, and if they lack a lake organization (lake organizations often provide alternative means of data collection through lake grants).

Water Quality Indicators

At a minimum, monitoring surveys will include: water chemistry samples for the Trophic Status Index, an aquatic plant point-intercept survey, and a shoreland habitat survey. The water chemistry group of parameters follows WisCALM guidance at a minimum. This includes Secchi depth, water temperature and dissolved oxygen profiles, and an epilimnetic sample of total phosphorus and chlorophyll a taken three times during the summer index period (July 15 – September 15) for two years. If lakes are targeted for blue green algae management, then blue green algae counts, microcystin, and phycocyanin are also sampled.

Aquatic plant point-intercept data are collected according to methods detailed in the following protocol: PI-Protocol-2010.pdf. Aquatic plant management relies heavily on this data. Plant-based biocritera metrics and rules are currently in development and will hopefully be codified by 2017. Thus, lake condition assessments will soon rely on plant point-intercept data in addition to the Trophic Status index and shall become a routine monitoring parameter.

Littoral and riparian habitat degradation is one of the major stressors to Wisconsin lakes. A shoreland habitat monitoring protocol was developed by the National Lakes Assessment, and will be used more broadly in Wisconsin lakes. Because the NLA shoreland habitat method can be implemented in a short period of time, the future goal is to routinely conduct one survey on all lakes that are monitored, independent of the monitoring objective. A more detailed shoreland habitat survey is needed for lake-specific management actions (e.g., zoning permits, critical habitat designations, habitat restoration efforts, dam regulation, high capacity well permits, etc.). A variety of techniques have been used in Wisconsin, but WDNR does not have a standardized protocol for detailed habitat surveys. A future goal is to establish intensive shoreland habitat monitoring protocols and metrics for management purposes.

Protocols for monitoring lake levels are in development (see Lake Level Monitoring below). On select lakes, gages will be surveyed and installed in spring and then surveyed and removed in fall. Citizen volunteers will monitor water levels at least monthly. In areas with homogenous geology, piezometers near the lake shore may be monitored as indicators of lake levels instead (e.g., Central Sands). Water levels of reservoirs are also monitored as part of the dam permitting process.

Data Management

As with the LTT Lakes and CLMN programs, water chemistry data are stored in SWIMS. Plant point-intercept data are currently stored on individual computers. Capacity in SWIMS for storing this data is planned. Capacity to house two types of shoreland habitat data is also on the list for programming into SWIMS. Water level data is captured in SWIMS.


Water chemistry data are summarized from the SWIMS database and the DNR's Lakes website, where summary reports and graphs from SWIMS are available for downloading and review. The data collected for lakes is also summarized on a biennial basis for the purpose of reporting on the status of the state's waters for the Integrated Water Quality Report to Congress (every two years). The next reporting period is 2016. The data will also be used for key parameter package analyses and statewide condition summaries. New reports need to be developed for plant and habitat surveys and water level data.

Programmatic Evaluation

Directed Lake Surveys will be re-evaluated each work planning cycle.

Last revised:

Tuesday May 30 2017