Is groundwater acid also?

Groundwater is an important part of our planet's water cycle. The surface water, mainly from rain, runs off over the ground and fills creeks, rivers, lakes and wetlands. A small amount of the surface water does not run off, but instead seeps underground. This underground water is called ground-water. Groundwater fills the spaces that are found in the soil and rocks and eventually flows downhill, just like creeks. The place that the groundwater is first observed as you dig down from the surface into the rocks and soil below is known as the water table. If you live in an area where your creek is acid, most likely the groundwater will also be acid.

Tools and things you will need

• Gloves
• Rubber boots
• Shovel
• A short length of PVC pipe

What to do?

1. Test your creek pH with litmus paper.
2. Move away from the stream in a line (transect) and push a pipe down into the sediment, or dig a hole with a shovel.
3. Collect the water and test the pH with litmus paper.
4. Test another distance away from your creek.

What did you see?

1. How far down did you have to dig to find groundwater as you moved away from the creek?
2. Was the underground water the same chemistry as the creek?
3. What else did you see?

What do you conclude?

1. Would acids leak into the groundwater from the creek, or from other underground sources?
2. What are your conclusions? "Write down what you think."