It looks like you might be asking for transition words or phrases to fill in the blank in your sentence. Common options could include:
- Therefore
- Consequently
- As a result
- Hence
From these choices, the most appropriate transition would likely be "As a result."
So the completed sentence would read: "People used twice as much water as the rule allowed. As a result, the well ran dry."
If you have specific options to choose from, please share them!