Assessing Septic System Discharge to Lakes

Project Details by Fiscal Year
2011 Fiscal Year Funding Amount
Fund Source
Environment & Natural Resources Trust Fund
Recipient Type
State Government
Start Date
July 2010
End Date
June 2014
Counties Affected
Project Overview

Pharmaceuticals, hormones, and other contaminants of emerging concern are increasingly being found in surface waters in Minnesota, including the state's lakes. Recent research surveying Minnesota lakes found that the most frequent occurrence of these chemicals was in lakes with a high density of septic systems. In river ecosystems some of these chemicals have been known to cause extinction of forage fish species and abnormal sexual development in other fish species, such as bass and walleye. However, little is known about how these compounds affect fish populations in lake ecosystems. Researchers from the U.S. Geological Survey, St. Cloud State University, and the Minnesota Department of Health will cooperatively use this appropriation to help assess which of these chemicals are most frequently present in lakes with high septic system concentration and determine whether native fish populations are being affected. Part of this appropriation will help pay for specialized equipment to study these chemical compounds, expanding the capability of the research laboratory at the Department of Health.

The current study (1) sampled 20 Minnesota lakes that receive groundwater under the potential influence of septic systems to determine the occurrence of pharmaceutically active compounds (PhACs) and endocrine active compounds (EACs), (2) assessed watershed and groundwater characteristics that may contribute to the frequency of PhAC and EAC detections, (3) assessed the histo-pathology of actively spawning bluegill sunfish for biomarkers of EAC exposure to compounds in the near-shore zone of four target lakes, and (4) enhanced EAC analytical capabilities at the Minnesota Department of Health (MDH) through the purchase of new analytical equipment. Study lakes were chosen based on depth to water table, septic system density regardless of functionality, bluegill nesting habitat, and groundwater temperature surveys in the near-shore zone. Lake water or lake-sediment pore water (water stored between sediment particles,contained within the lake-bed sediment) samples were collected and analyzed for a broad suite of 179 PhACs, EACs, and other waste compounds. All surface water samples and over three quarters of pore water samples had at least one compound detected. Overall, 43 of 69 (62%) waste compounds and 5 of 110 (4%) pharmaceuticals were detected in all samples. Twelve known or suspected endocrine active compounds were detected in at least one lake. On average, the prevalence of detections normalized to the number of compounds tested was three to four times higher in near-shore lake water than in near-shore pore water. Actively spawning male bluegill sunfish were collected from reference and groundwater discharge sites in four lakes. Pathologies were more common in fish collected at near-shore sites when compared to fish collected across entire lakes in the 2008 statewide study. The greater abundance of indicators of adverse biological impact suggests that a lake-wide sampling of fish will underestimate the impact of contaminant exposure to fish during reproductively important life stages.

Information from this project has been disseminated to scientific audiences via presentations at Minnesota Water Resources and Midwest Groundwater Conferences.

Project Details
Legal Citation / Subdivision
M.L. 2010, Chp. 362, Sec. 2, Subd. 05e
Appropriation Language

$594,000 is from the trust fund to the commissioner of health for department activities and for an agreement with the United States Geologic Survey in cooperation with St. Cloud State University to develop quantitative data on septic system discharge of estrogenic and pharmaceutical compounds and assess septic and watershed influences on levels of contamination and biological responses in Minnesota lakes. The United States Geologic Survey is not subject to the requirements in Minnesota Statutes, section 116P.10. This appropriation is available until June 30, 2013, by which time the project must be completed and final products delivered.

2011 Fiscal Year Funding Amount
Proposed Measurable Outcome(s)

Click on "Final Report" under "Project Details".

Measurable Outcome(s)

Click on "Final Report" under "Project Details".

Project Manager
First Name
Last Name
Organization Name
Street Address
2280 Woodale Dr
Mounds View
Zip Code
(763) 783-3131
Administered By
Administered by

P.O. Box 64975
St. Paul, MN 55164-0975