That depends a great deal on the size of the lake and what of the many aspects you would like to measure. Let's take Lake Michigan.
I would measure the...
width and length in miles
surface area in square miles
depth in feet
volume in cubic miles
retention time in years
elevation in feet
pollutants in parts per million
You would use a thermometer to measure your temperature.
measure liquids , measure length,.....
The measurement is for cations and anions.
Volume is measure as width times height by depth no matter the system you're using. The metric system would just define the type of measurement you would use, such as liters instead of gallons.
Gallons are a measurement of volume, and grams are a measurement of mass (weight), so it would depend on what type of material you measuring.
meters
meters Man Okey
You would use a thermometer to measure your temperature.
measure liquids , measure length,.....
Grams
Joules
foot
The measurement is for cations and anions.
That type of measurement would be referred to as a qualitative measurement.
The general answer is "linear measurement". Specific possibilities would be feet, yards, and meters.
psi-pounds per square inch.
lightyears