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Temperature/Dissolved Oxygen Meters

Did you know that you can collect temperature and dissolved oxygen data on your lake? The Indiana Clean Lakes Program has a number of meters around the state that volunteer lake monitors can borrow to take readings. Collecting temperature and dissolved oxygen data can give you valuable insight into the inner workings of your lake.


Procedure for Using the YSI Temperature and Dissolved Oxygen Meters on Volunteer Monitored Lakes

The Indiana Department of Environmental Management (IDEM) has purchased seven YSI Model 550A temperature and dissolved oxygen meters for participants in the Volunteer Lake Monitoring Program to use on their lakes.  We hope that our volunteers will be interested in measuring temperature and dissolved oxygen profiles of their lakes. 

Temperature profiles not only tell us whether the lake is stratified, but also the depth of the surface mixing layer (called the epilimnion) and the depth of the bottom non-mixed layer (called the hypolimnion).  The oxygen profile tells us whether oxygen is plentiful throughout the lake or if not, the amount of the lake that has insufficient oxygen.  This, of course, is particularly important to the fish and gives us insight into how biologically productive the lake is. 

For Example:

Temperature/DO example profile

Martin Lake is thermally stratified and has a fairly shallow mixing zone (epilimnion).  Bottom temperatures are very cold.  Oxygen declines significantly below 8 meters.  This suggests that there is significant Biochemical Oxygen Demand (BOD) in the sediments.  This organic matter is food for bacteria that consume the oxygen as they feed.

Because both temperature and dissolved oxygen change with the seasons, volunteers are encouraged to take additional measurements on their lake – but no more than once per month.

Each meter is expensive ($1,000) and fragile.  Please use with care.  You will be trained by SWCD or SPEA staff before you are allowed to borrow a meter.  If you are uncertain about features of the meters or how to use them after you’ve been trained, please call for refresher instructions.

Here is the procedure for borrowing the meters:

  1. Call the nearest SWCD office or SPEA to reserve the meter for a specific date (addresses and telephone numbers are given following).  Arrange a time when you can pick up the meter.
  2. The local SWCD or SPEA staff will train you on proper use and care of the meter during your first visit.  This training will take approximately 30 minutes.
  3. You will have to sign for the meter on a standard form.
  4. Take the meter home and make the measurements on your lake (measurement instructions are on a separate sheet and enclosed in the meter case).
  5. Return the meter to the SWCD office or SPEA the same or next day.  We can only allow you 1-2 days at a time with the meter so that it is available for others to use.


Where to Sign Out a Meter

Elkhart County SWCD
Elkhart County 4-H Fairgrounds
17746-B County Road 34
Goshen, IN 46528
(574) 533-3630 ext. 3
Contact: Nancy Brown

  Fulton County SWCD
1252 E. 100 S, Suite D
Rochester, IN 46975-8036
574-223-3220 ext. 3
Contact : Chris Gardner
Kosciusko County SWCD
217 E. Bell Drive
Warsaw, IN  46582
(574) 267-7445  ext. 116
Contact: Darci Zolman
  LaGrange County SWCD
910 South Detroit Street
LaGrange, IN   46761-2235
(260) 463-3471  ext. 3
Contact: Dona Hunter
Marshall County SWCD
2903 Gary Drive
Plymouth, IN 46563-1825
574-936-2024 ext. 3
Contact: Wanda Norris
  Merry Lea Environmental Learning Center
2388 S 500 W
(260) 799-5869
Contact: Jane Litwiller



School of Public and Environmental Affairs
Indiana University
1315 East 10th Street
Bloomington, IN   47405
(812) 855-4556
Contact:  Bill Jones
  Steuben County SWCD
Peachtree Plaza 200
1220 N. 200W
Angola, IN  46703-8901
(260) 665-3211  ext. 3
Contact: Kayleen Hart


Instructions for Taking Temperature and Dissolved Oxygen Measurements

Temperature and oxygen profiles should generally be made from the deepest water depths in your lake.  You will have to anchor your boat – otherwise drift will cause inaccurate depth measurements.

1. Turn on meter and calibrate according to instructions.  

**The  meter must be turned on for 20 minutes prior to calibration to allow the electronics to stabilize.

2. Once calibrated, remove probe from calibration/storage chamber.

3. Lower probe into water to desired depth.
(Always start measurements with the probe at just below the water’s surface.  Then make measurements at one-meter intervals, for example, 1m, 2m, 3m, 4m, etc.  The cord is marked with tape at these intervals.  Be careful to not let probe hit the bottom sediments.)

4. Press MODE button until meter is in “dissolved oxygen % air saturation” mode.

5. Allow temperature to stabilize (about 30 seconds). 

6. Record temperature on a data sheet.

7. Raise and lower the probe gently (about 2 inches per second) until % air saturation stabilizes.  Record this percentage.

8. Press MODE button once so dissolved oxygen is displayed in “mg/L”.  Again raise and lower the probe until stable.  Record this value.

9. Lower probe to next depth.

10. Press the MODE button to return to “% air saturation” mode.  Repeat steps 5 – 9 as necessary.

11. When finished, rinse probe with distilled water from the squirt bottle.  Place probe in storage chamber.  Turn off meter.

REMEMBER: Never hold the meter over the water.  Keep it securely inside the boat.

 12. Send completed data sheet to:  Sarah Powers, SPEA 371, Indiana University, Bloomington, IN  47405 or use our online data entry form.

 Report any difficulties to SWCD staff.