I am interested in hearing from people who make their own Secchi disks. I would like to know how you make them. Thank you!
Editor, The Volunteer Monitor Newsletter
50 Benton Avenue
San Francisco, CA 94112
Responses to Question 1
Date: Thu, 22 Jan 2004 10:35:39 -0500
From: Elizabeth Herron
Subject: [volmonitor] Re: Secchi, transparency tube photos & info
In response to Ellie’s inquiry regarding making Secchi disks, I would like to offer this link to our website for our “Measuring Water Clarity” factsheet. Among other things, this pdf document includes instructions for making your own disk, as well as a primer on basic water clarity.
Then of course, the definative site for measuring water clarity is the “Great North American Secchi Dipin” found online.
Date: Thu, 24 Jul 2008 09:23:24 -0500
From: Anne Lewis <firstname.lastname@example.org
Subject: [volmonitor] t-tube sample size
I am in the process of putting together a loaner kit for teachers who want
to try volunteer monitoring. I expect most of the borrowers to be upper
elementary/middle school teachers. The kit will include 60cm. transparency tubes. In looking at the different SOPs out there in volunteer monitoring land, I notice that the recommendation for collecting the sample is to use a large bucket.
Since the volume of a 60cm tube is a little less than a liter, I am
wondering about the pros and cons of using a one liter container to
collect the sample. The benefit would be a greater chance for a
homogenized sample; the drawback – a risk of spilling and sloshing so the
sample size is "short".
Information and Education Project Administrator
Project WET South Dakota
SD Leopold Education Project
SD Discovery Center
805 W. Sioux Ave.
Pierre, SD 57501
Responses to Question 2
Date: Fri, 25 Jul 2008 12:57:46 -0500
From: Erik Olson
Subject: RE: [CSREESVolMon] Fwd: [volmonitor] t-tube sample size
Two things of comment.
1. We noticed during our river surveys in Northern Wisconsin that in some cases the 120 cm transparency tubes were even to short. And on every stream we sampled the 60 cm was way to short. With that being said we were working in Northern Wisconsin were watersheds are still covered with more “undisturbed” surfaces. So it depends on the stream or river, but I would recommend having a couple 120 cm tubes on hand.
2. It seemed pretty easy for us to just fill up the tubes in the river/stream instead of transferring water in a bottle then to the tube. I prefer filling the tube directly up in the stream if possible over filling a bottle and then filling the tube. Although, it would definitely be an option in the stream was too shallow or too dangerous to wade into, or if your crew wanted to keep their feet relatively dry. And I suppose if you fill directly from the stream you run the risk of getting large objects, i. e. leaves, into your sample.
Natural Resource Specialist
Lac Courte Oreilles Ojibwe Community College