Monitoring Methods: Transparency

Three volunteers practice using a transparency tube next to a stream.

Recording transparency

Monitoring Methods

When Do You Monitor?

Time Needed

Equipment Needed

Record transparency each month from May through October.

 

 

5 - 10 minutes

 

 

 

 

 

Procedure

  1. Walk into the downstream from the sampling location. Be careful not to stir up the bottom sediment upstream of your sampling location. 
  2. Face upstream (against the current) in the middle of the stream.
  3. Collect your water sample by plunging your transparency tube or collection bucket 8-12 inches beneath the surface or halfway down from the surface. Scoop away from your body and into the current. 
  4. Scoop water into the tube so it is filled to the top, or use a bucket to collect additional water from the stream at the site to fill the tube to the top.
  5. Return to shore with the sample.
  6. Stand out of direct sunlight. If you cannot get to a shady place, use your body to cast a shadow on the tube.
  7. If you are wearing sunglasses, remove them. Then look for the target (black and white) disc on the bottom of tube. If disc is visible, record the length of the tube (e.g., 120 cm) on the data sheet.
  8. If target disc is not visible, have your partner let water out a little at a time using the valve at the bottom of the tube until the disc is just visible. That is, have them stop letting water out immediately when you can just see the contrast between black and white on the disc.
  9. Read the height of water in the tube using the measuring tape on the side of the tube.
  10. Record the measurement on your data sheet in centimeters.
  11. Dump contents of the tube on the ground.
  12. Collect a new sample repeating steps 3 through 11.
  13. Record the second measurement on your data sheet.
  14. Add both readings, divide by 2, and record this average on your data sheet.

 

From Transparency to Turbidity

Since we assess water clarity visually, we don’t directly measure how many suspended particles are in the water. Instead we measure the transparency of the water, which takes into account both color and suspended particles. We do, however, provide volunteers with a conversion chart so that you can estimate the turbidity measurement in nephelometric turbidity units (NTUs). Volunteers are not expected to calculate turbidity - it's more for your reference.

lined paper  Learn more in the WAV factsheet "Transparency:  A Water Clarity Measure." Links to an external site.

 

Video Demonstration

Watch this video to learn WAV's monitoring transparency method.