Great Lakes Echo - Environmental news of the Great Lakes region

Great Lakes Echo (https://greatlakesecho.org/2011/03/03/get-out-your-lab-coat-lake-monitoring-season-is-in-session/secchi-disk-velo-steve-flickr/)

Secchi disk-Velo Steve-Flickr

Published March 3, 2011 at 500 × 400 in Get out your lab coat–lake monitoring season is in session

A secchi disk is lowered into a lake to measure water clairty. Photo: Velo Steve via Flickr.