Water Transparency and the Secchi Disk Test

This is a photo taken from the Minnesota Pollution Control Agency NOT our MPA volunteer actually performing the annual Secchi test on Manchaug Pond.

I’ve been “visiting” the land of 10,000 lakes on the web as they seem to be very committed to water quality as well as experienced in taking action! For instance, through legislation Minnesota has used watershed districts since 1955 to protect their many lakes. One source reported 49 watershed districts, another 249! They have the statutes and regulations all layed out as to how the district functions, its purpose and powers. They even have a professional association for the watershed districts! Anyway lets get back to the Secchi test!

What is a Secchi? Well, every MPA Annual Meeting, our gentleman experienced Secchi volunteer gives a quick overview and a report. He has been doing it for years! Thanks Don! (Oh sorry, I’m not suppose to use names, but couldn’t resist!) Minnesota reports: “Secchi transparency (clarity) is a quick and easy measurement of lake’s water quality. Secchi transparency provides an indirect measure of the amount of suspended material in the water; which in many Minnesota lakes – is the amount of algae in the water.” Here in swallow Manchaug Pond we not only see algae but also sediment and organic material (decomposing pine needles, leaves, etc) brought in by erosion and runoff from the watershed.

The Secchi disk is one small monitoring device we have been using for many years on Manchaug Pond. Our efforts with the Nonpoint Source Pollution Grant project and the watershed district are actions we are and can take to keep our lake healthy. This positively impacts down stream as well- Steven’s Pond, the Mumford River, the Blackstone…

Click the title of this post to take you to a site which shows the Secchi disk in action. “Watch the slide show that follows the change in Secchi transparency for Minnesota lakes from four different classifications of lake water quality.” Note that as the water warms, algae growth increases causing water clarity to decrease.

Click on to the title of this post to take you to the Secchi slideshow! And stay tuned for more information 🙂

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