To convert gallons to liters, you can use the conversion factor of 3.8 liters per gallon.
So, to find out how many liters Michael used, you can multiply the number of gallons by the conversion factor:
\[ 785 \text{ gallons} \times 3.8 \text{ liters/gallon} = 2983 \text{ liters} \]
Therefore, the closest measurement to the number of liters Michael used during that month is approximately 2983 liters.