- Remove funnel from top of can and clean all dirt and debris
- Locate measuring mark on side of can; if no mark present, use the seam of the can
- Measure distance to oil surface from rim of can
- Record distance in yellow field book and subtract from previous visit to determine depth of rainfall
- If oil cap has turned white/milky:
- Pump material into “ook” container
- Add 1” of oil to can
- Measure new distance to water surface and record value in yellow field book
- Replace funnel on top of cap
For the Aspiring Hydrographer
