Devil’s Lake Monitoring 7/1/2018 - 6/30/2019
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Purpose

Devil’s Lake – the centerpiece to Wisconsin’s most popular state park – has been monitored by the Bur. of Research/Science Services with vertical profile sampling throughout the open water period since 1986, first to document and understand the lake’s water quality problems that were shown to be directly or indirectly linked to excessive internal loading/recycling of phosphorus (P). To reduce internal P loading, a hypolimnetic withdrawal system was evaluated and then installed in the summer of 2002 and operated in late summer/early fall when bottom water P concentrations are typically highest. Lake monitoring has continued to this day to evaluate the effectiveness of the hypolimnetic withdrawal system to reduce the lake’s water quality problems and to return the lake to its historically infertile trophic state. This monitoring is critical for making day to day siphon pipe management decisions, as well as future decisions about if and when fall P removal should be halted in response to changing lake chemistry.

Objective

All monitoring is conducted at the deep hole, which is the location of the intake end of the pipe. Monitoring of Devil’s Lake (WBIC 980900) will be conducted on 8 dates from late April through early November following protocols and procedures consistent with previous years of monitoring. Funds requested to support these 8 lake samplings are 80 hours of LTE time (plus fringe and indirect costs). Richard Lathrop will conduct this monitoring with the assistance of non-paid volunteers as he has done for the past 15 years. The travel money is to support the 8 monitoring trips to the lake.

Outcome

This project continues the monitoring initiated in 1986 and continued each year both before and after the installation of the bottom withdrawal pipe system in the summer of 2002.

Study Design

The lake monitoring done over 8 sampling events (i.e., spring turnover sampling in late April, sampling every 3 weeks from late June through early October [6 samplings], and fall turnover in early November) entails not only collecting temperature and dissolved oxygen profiles along with traditional trophic state indicator data (i.e., Secchi depth; epilimnetic P and Chl-a concentrations), but also extensive sampling of the lake’s hypolimnion with bottom-up profiles of P, iron (Fe), and sulfate concentrations being collected during the summer and early fall season as a response to hypolimnetic anoxia. These hypolimnetic parameters are needed to elucidate changes in the lake’s internal P recycling rates, Fe scavenging potential of P, and sulfate reduction rates (linked to bacterial methylation of mercury). This 8 monitoring date schedule is a reduction from the historical 12 lake samplings per year conducted through June 2017 when the monitoring was reduced to 8 samplings due to budgetary constraints, but the 8 samplings retain the most important monitoring objectives and water quality evaluation indices.

Related Reports

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Competitive Projects
Lake Program Activities
SCR_09_CMP18
2018
Proposed
 
Activities & Recommendations
Monitor Water Quality or Sediment
This monitoring is critical for making day to day siphon pipe management decisions, as well as future decisions about if and when fall P removal should be halted in response to changing lake chemistry.
 
Watershed
Lower Baraboo River
 
Waters
Devils Lake
Monitoring Data
Lake Details