An official website of the United States government.

We've made some changes to EPA.gov. If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

The Lake Guardian

The R/V Lake Guardian sampling in Lake Huron (Image Credit: Michael Milligan)The R/V Lake Guardian sampling in Lake Huron (Image Credit: Michael Milligan)The Research Vessel (R/V) Lake Guardian is the largest research vessel in the U.S. EPA fleet and the largest research vessel operating on the Great Lakes. The R/V Lake Guardian is owned by the EPA Great Lakes National Program Office (GLNPO). The R/V Lake Guardian assists GLNPO in monitoring and reporting on the status and trends of the Great Lakes ecosystem. Annual surveys that sample water and biological life at designated locations in all five Great Lakes (Superior, Michigan, Huron, Erie and Ontario) are conducted by the R/V Lake Guardian

On this page:


The Mission of the R/V Lake Guardian

The R/V Lake Guardian assists with GLNPO's mission for monitoring and reporting on the status and trends of the Great Lakes ecosystem. GLNPO has mandates to help restore and protect the health of the Great Lakes as required under the Great Lakes Water Quality Agreement and the Great Lakes Restoration Initiative. Sampling from aboard the R/V Lake Guardian, operating on all five Great Lakes, is used to monitor the water quality and health of the lakes. The R/V Lake Guardian also provides educational opportunities around the Great Lakes basin.

Top of Page

The R/V Lake Guardian's Yearly Survey Activities

The R/V Lake Guardian conducts sampling surveys on all five Great Lakes during both the spring (late March, after ice break-up) and summer (August) seasons. The spring survey monitors lake health during a time of low biological activity, when the lakes are well-mixed. The summer survey monitors lake health during the season of high biological activity, when the lakes are stratified. During these surveys, water, plankton and benthos samples are taken at designated stations throughout each lake. These monitoring surveys have been ongoing in the lakes since 1983, resulting in an exceptional long-term monitoring dataset for evaluating the health of the Great Lakes ecosystem through time.

Map showing the R/V Lake Guardian annual survey sampling locations on the Great LakesMap showing the R/V Lake Guardian annual survey sampling locations on the Great Lakes.In addition to the annual spring and summer surveys, the R/V Lake Guardian conducts: 

  • Dissolved oxygen surveys on Lake Erie,
  • Educator cruises through the Illinois-Indiana Sea Great, and
  • Cooperative Science and Monitoring Initiative (CSMI) surveys, thoroughly sampling one Great Lake every year, rotating on a five-year cycle.

The R/V Lake Guardian 2016 Annual Report contains information on most recent surveys.

Top of Page

The Ship Specifications of the R/V Lake Guardian

The R/V Lake Guardian is 180 feet in length, with a gross tonnage of 283 tons, a displaced tonnage of 850 tons, and a cruising speed of 11 knots. It has a berthing capacity of 41 people, including 14 crew members and 27 visiting scientists.

Top of Page


The Types of Sampling Equipment and Laboratories Used Aboard the R/V Lake Guardian

The R/V Lake Guardian is equipped with three dedicated laboratories:

  • a general purpose or "wet" laboratory,
  • chemistry laboratory, and
  • biology laboratory.

The wet laboratory is the main collection space where samples are first brought onboard. Raw water samples are processed in the wet laboratory, with a subset passing on to the chemistry laboratory for on-board nutrient analysis. Zooplankton, phytoplankton, and chlorophyll-a samples are processed in the biology laboratory.

A scientist onboard the R/V Lake Guardian filtering raw water samples in the wet laboratory.A scientist onboard the R/V Lake Guardian filtering raw water samples in the wet laboratory.The ship is equipped with state-of-the-art limnology sampling equipment. The Rosette water sampler, outfitted with a Sea-Bird multi-parameter profiler (conductivity, temperature and depth) and other water quality probes and sensors, is the main water sample collection device. The Rosette collects water column data and raw water samples in its twelve Niskin sampler bottles at designated depths at each sampling station. Phytoplankton samples are also collected from the Rosette's raw water.

The Rosette water sampler being lowered into Lake Superior to collect raw water samples at different depths for chemical and biological analysesThe Rosette water sampler being lowered into Lake Superior to collect raw water samples at different depths for chemical and biological analyses.

Sediment samples are collected from the bottom of the lakes using a PONAR sampler, a box corer and a multi-corer. A benthic sled is also deployed for video analysis of the lake bottom and collection of lake benthos and epibenthos. Zooplankton and Mysis samples are collected by pulling nets vertically through the water.

Scientists deploying the multi-corer off the R/V Lake Guardian in Lake Erie to collect sediment core samples.Scientists deploying the multi-corer off the R/V Lake Guardian in Lake Erie to collect sediment core samples.

Top of Page


How Scientists Request to do Research Aboard the R/V Lake Guardian

During monitoring surveys, EPA offers opportunities for scientists from federal and state governments and universities to conduct research aboard the R/V Lake Guardian. Research compatible with the standard sampling performed at each station is especially encouraged.

The R/V Lake Guardian supports a number of projects every year:

  • Research requests for projects funded by U.S. EPA have the highest priority;
  • Other projects related to EPA's work receive the second highest priority;
  • Projects funded by outside agencies receive the third highest priority.

To request time aboard the R/V Lake Guardian, contact Eric Osantowski (osantowski.eric@epa.gov). 

Top of Page