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Peter L Lenaker

Pete Lenaker is a Physical Scientist with the Upper Midwest Water Science Center.

Education and Certifications

  • M.S. in Oceanography and Coastal Sciences, Louisiana State University, 2009

  • B.S. in Environmental Science, Western Washington University - Huxley College of the Environment, 2006

  • A.A. in Environmental Studies, North Seattle College, 2003

Science and Products

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Various types and sizes of plastics collected from the Kinnickinnic River, WI

MMSD Watercourse Corridor Study: Contaminants in Water and Sediment

There are many kinds of chemical, physical, and biological contaminants contained in water and sediment, and new or “emerging” contaminants are continually being discovered. USGS investigations of contaminants in the MMSD Watercourse Corridor Study include studies of PFAS, PAHs, microplastics, and wastewater contamination as well as modeling long-term trends in water quality.
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Upper Midwest Water Science Center
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MMSD Watercourse Corridor Study: Contaminants in Water and Sediment

There are many kinds of chemical, physical, and biological contaminants contained in water and sediment, and new or “emerging” contaminants are continually being discovered. USGS investigations of contaminants in the MMSD Watercourse Corridor Study include studies of PFAS, PAHs, microplastics, and wastewater contamination as well as modeling long-term trends in water quality.
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Illustration showing potential sources of pathogen contamination for Lake Michigan beaches

Human and Bovine Virus Prevalence in Some Great Lakes Tributaries Influenced by Watershed-Specific and Seasonal Characteristics

Human enteric and bovine-specific viruses were detected in eight Great Lakes tributaries. Presence and concentration of human viruses increased in watersheds with greater than 25 percent urban influence and more than 2,900 people per square kilometer. Similarly, bovine viruses increased in watersheds having greater than 40 percent agricultural land influence and cattle densities greater than 50...
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Ecosystems, Environmental Health Program, Toxic Substances Hydrology
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Human and Bovine Virus Prevalence in Some Great Lakes Tributaries Influenced by Watershed-Specific and Seasonal Characteristics

Human enteric and bovine-specific viruses were detected in eight Great Lakes tributaries. Presence and concentration of human viruses increased in watersheds with greater than 25 percent urban influence and more than 2,900 people per square kilometer. Similarly, bovine viruses increased in watersheds having greater than 40 percent agricultural land influence and cattle densities greater than 50...
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Select optical signals from water samples collected on the Menomonee River, Underwood Creek, and Jones Island Water Reclamation Facility from 2017-2019, and time-series optical sensor and one-hour mean streamflow data from the Menomonee River 2017-2018

5-day composite river water samples were collected from two sites: Menomonee River (U.S. Geological Survey station number 04087142) and Underwood Creek (U.S. Geological Survey station number 04087088) in Milwaukee, Wisconsin. 5-day composite wastewater (raw sewage) influent samples were also collected from the Jones Island Water Reclamation Facility (U.S. Geological Survey station number 430125087
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Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center

Great Lakes tributary pharmaceutical water samples from water year 2018

This data release provides water chemistry results and quality assurance data for samples collected from Great Lakes tributaries in the states of Minnesota, Wisconsin, Michigan, Indiana, Ohio, and New York. In total, 158 chemicals were analyzed which are primarily pharmaceuticals. Between one and four water samples were collected at 37 sampling locations between November 2017 and July 2018 resulti
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Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center

Optical signals of water for prediction of wastewater contamination, human-associated bacteria, and fecal indicator bacteria in surface water of Great Lake tributaries from 2011 to 2016

Data are from water samples collected from tributaries of the Great Lakes at three different drainage basin scales, including 1). watershed scale: 8 tributaries of the Great Lakes, 2). subwatershed scale: 5 locations from the greater Milwaukee, Wisconsin area, and 3). small scale: 213 storm sewers and open channel locations in three subwatersheds within the Great Lakes Basin including the Middle B
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Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center

Microplastics in the water column and sediment in Milwaukee-Area streams, the Milwaukee Harbor, and Lake Michigan, 2016

This dataset describes the quantity, morphology, and polymer identity of microplastics in the water column and surficial sediments of Milwaukee-Area streams, the Milwaukee Harbor, and Lake Michigan (Wisconsin). Water samples were collected at 10 locations, 2-4 times each, from May to September, 2016. At the 4 shallowest locations, water was collected only at the water surface. At the remaining 6 l
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Idaho Water Science Center

Microplastics in the surficial benthic sediment from Lake Michigan and Lake Erie, 2013 and 2014

This dataset describes the quantity, morphology, concentration and polymer identity of microplastics in surficial benthic sediment of Lake Michigan and Lake Erie. Lake Michigan sediment samples were collected at 20 locations in September, 2013 and Lake Erie sediment samples were collected at 12 locations in September, 2014 while on-board the R.V. Lake Guardian. Sampling and analysis methods are de
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Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center

Human-associated indicator bacteria and human specific virus loads, sample volumes, and drainage areas for six Menomonee River Watershed sampling locations

Human-associated indicator bacteria and human specific viruses in the Menomonee River watershed in Milwaukee, WI were investigated from April 2009 to March 2011 at six sampling locations within the watershed. We used concentration and water volume data from runoff-event and low-flow periods to compute loads for each sample collected, and subsequently used those loads, and drainage area from each
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Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center
Filter Total Items: 26
Milwaukee River at Cherry Street Bridge looking downstream
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Multi-parameter meter installed at Milwaukee River Cherry St. location
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Microplastics Sampler next to white utility van
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Looking upstream North Branch Oak Creek at South Wildwood Drive at Oak Creek, WI
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Oak Creek at South 31st Street at Franklin, Wisconsin looking upstream
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Underwood Creek Tributary near Oak Leaf Trail at West Allis, Wisconsin
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Close up view of a Turner C3 sensor fluorometer
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Flow-through sensor for measurement of three different optical signals
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Ultrafilters and bottles
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24-bottle automatic sampler to collect water samples
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Chromophoric Dissolved Organic Matter and Tryptophan sensors
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Prefilter and Ultrafilter assembly from Menomonee River, WI
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Automated, large-volume virus water sample filtration and collection system
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A USGS scientist collecting a discrete water-quality sample
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Little Muskego Lake sediment core mounted on sediment extrusion device
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USGS scientist inspects three sediment cores from Lake Mendota, WI.
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Lake sediment slice Lake Mendota
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A custom automated pathogen sampler and schematic illustration.
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Microplastic sample preserved with 10% isopropyl alcohol
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Scientist collecting sediment core from Little Menomonee River, WI
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Surface water sampling for microplastics in Lake Michigan near Milwaukee, WI.
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Prioritizing pharmaceutical contaminants in Great Lakes tributaries using risk-based screening techniques

In a study of 44 diverse sampling sites across 16 Great Lakes tributaries, 110 pharmaceuticals were detected of 257 monitored. The present study evaluated the ecological relevance of detected chemicals and identified heavily impacted areas to help inform resource managers and guide future investigations. Ten pharmaceuticals (caffeine, nicotine, albuterol, sulfamethoxazole, venlafaxine, acetaminoph
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Upper Midwest Water Science Center

Risk-based prioritization of organic chemicals and locations of ecological concern in sediment from Great Lakes tributaries

With improved analytical techniques, environmental monitoring studies are increasingly able to report the occurrence of tens or hundreds of chemicals per site, making it difficult to identify the most relevant chemicals from a biological standpoint. For this study, organic chemical occurrence was examined, individually and as mixtures, in the context of potential biological effects. Sediment was c
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Ecosystems, Water Resources, Upper Midwest Environmental Sciences Center, Idaho Water Science Center, Upper Midwest Water Science Center

Optical properties of water for prediction of wastewater contamination, human-associated bacteria, and fecal indicator bacteria in surface water at three watershed scales

Relations between spectral absorbance and fluorescence properties of water and human-associated and fecal indicator bacteria were developed for facilitating field sensor applications to estimate wastewater contamination in waterways. Leaking wastewater conveyance infrastructure commonly contaminates receiving waters. Methods to quantify such contamination can be time consuming, expensive, and ofte
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Water Resources, California Water Science Center, Upper Midwest Water Science Center

Spatial distribution of microplastics in surficial benthic sediment of Lake Michigan and Lake Erie

The spatial distribution, concentration, particle size, and polymer compositions of microplastics in Lake Michigan and Lake Erie sediment were investigated. Fibers/lines were the most abundant of the five particle types characterized. Microplastic particles were observed in all samples with mean concentrations for particles greater than 0.355 mm of 65.2 p kg–1 in Lake Michigan samples (n = 20) and
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Upper Midwest Water Science Center

Primary sources of polycyclic aromatic hydrocarbons to streambed sediment in Great Lakes tributaries using multiple lines of evidence

Polycyclic aromatic hydrocarbons (PAHs) are among the most widespread and potentially toxic contaminants in Great Lakes (USA/Canada) tributaries. The sources of PAHs are numerous and diverse, and identifying the primary source(s) can be difficult. The present study used multiple lines of evidence to determine the likely sources of PAHs to surficial streambed sediments at 71 locations across 26 Gre
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Water Resources, Idaho Water Science Center, Upper Midwest Water Science Center

Vertical distribution of microplastics in the water column and surficial sediment from the Milwaukee River basin to Lake Michigan

Microplastic contamination was studied along a freshwater continuum from inland streams to the Milwaukee River estuary to Lake Michigan, and vertically from the water surface, water subsurface and sediment. Microplastics were detected in all 96 water samples and nine sediment samples collected. Results indicated a gradient of polymer presence with depth: low-density particles decreased from water
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Water Resources, Upper Midwest Water Science Center, Idaho Water Science Center

Human-associated indicator bacteria and human-specific viruses in surface water: a spatial assessment with implications on fate and transport

Hydrologic, seasonal, and spatial variability of sewage contamination was studied at six locations within a watershed upstream from water reclamation facility (WRF) effluent to define relative loadings of sewage from different portions of the watershed. Fecal pollution from human sources was spatially quantified by measuring two human-associated indicator bacteria (HIB) and eight human-specific vi
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Upper Midwest Water Science Center

Patterns of host-associated fecal indicators driven by hydrology, precipitation, and land use attributes in Great Lakes watersheds

Fecal contamination from sewage and agricultural runoff is a pervasive problem in Great Lakes watersheds. Most work examining fecal pollution loads relies on discrete samples of fecal indicators and modeling land use. In this study, we made empirical measurements of human and ruminant-associated fecal indicator bacteria and combined these with hydrological measurements in eight watersheds ranging
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Upper Midwest Water Science Center

Hydrologic, land cover, and seasonal patterns of waterborne pathogens in Great Lakes tributaries

Great Lakes tributaries are known to deliver waterborne pathogens from a host of sources. To examine the hydrologic, land cover, and seasonal patterns of waterborne pathogens (i.e. protozoa (2), pathogenic bacteria (4) human viruses, (8) and bovine viruses (8)) eight rivers were monitored in the Great Lakes Basin over 29 months from February 2011 to June 2013. Sampling locations represented a wide
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Water Resources, Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center

Organic contaminants in Great Lakes tributaries: Prevalence and potential aquatic toxicity

Organic compounds used in agriculture, industry, and households make their way into surface waters through runoff, leaking septic-conveyance systems, regulated and unregulated discharges, and combined sewer overflows, among other sources. Concentrations of these organic waste compounds (OWCs) in some Great Lakes tributaries indicate a high potential for adverse impacts on aquatic organisms. During
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Water Resources, Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center

Non-USGS Publications**

Rivera-Monroy, V.H., Lenaker, P., Twilley, R.R., Delaune, R.D., Lindau, C.W., Nuttle, W., Habib, E., Fulweiler, R.W., Castaneda-Moya, E. (2010) Denitrification in coastal Louisiana: A Spatial Assessment and Research Needs. Journal of Sea Research 63 (3-4): 157-172.

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

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Human Bacteria, Viruses from Sewage Found in Some Milwaukee Streams

Two types of human-associated bacteria and three types of human viruses were detected in Milwaukee streams within the Menomonee River watershed...

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Human, Cattle Viruses Detected in Some Great Lakes Tributaries

Human and bovine, or cattle, viruses were detected in a small percentage of some Great Lakes Basin streams, with human viruses more prevalent in urban...

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