While you have been carrying out your other fieldwork measurements, have you noticed anything in the river that shouldn’t be there?
Hopefully your sites have been relatively pollution free, but it is not unusual to see stuff dumped in rivers.
You can easily assess the pollution level of your river by doing some visual checks and as there is no need to go into the water, you might want to travel some distance downstream, to where the river is larger, maybe passing through a town. Results there may be rather different.
Print out a copy of the visual assessment chart for each location that you are going to visit. When you get there walk along the bank and have a good look in the water.
On each row of your chart you need to give your river a score between 1 and 5. So on the first row, if the water is totally clear put a tick in the column below 5. If you are surveying a moorland stream the water might be clear but also brown, so on the second row you might want to tick 2 or even 1. You’ll have to decide. (Yes, it’s another one of those subjective tests, where your friend might want to score it differently.)
If you want to collect a water sample for another simple test, then you need a clean jar. Half fill it with river water and put the lid on tight. Use the stopwatch on your phone to time for one minute, while you shake it like crazy. Then put it down and time how long it takes for any foamy bubbles to disappear. The more polluted the water, the longer it will take.
Whilst you are waiting for bubbles to vanish, keep an eye on the jar, but at the same time add up the score on your visual assessment chart. Less polluted has a high score and more polluted has a low score.
Compare your sites. Where is the most pollution?