Gage height vs lake elevation

Some USGS lake stations report gage height (parameter code 00065) instead of an elevation. Gage height is the height of the water surface above a fixed reference point at that station, called the gage datum. The reference is chosen locally and is often set so the numbers stay small and positive.

How to read it

A reading of 6.42 ft means the water is 6.42 ft above that station’s zero point. It does not mean the lake is 6 ft deep, and it is not the height above sea level.

What gage height is good for:

• Seeing whether the lake is rising or falling, and how fast
• Comparing today with past readings at the same station
• Comparing with local landmarks, if the lake association publishes levels on the same gage

Converting to elevation

USGS publishes the elevation of the gage datum for many stations. Add the gage height to that number to get an elevation. Be careful: gage datums are sometimes reset when stations are rebuilt, and older station records may use a different datum.

On Lakeglance, gauges that report gage height are labeled “ft (gage datum)” on the water level page. Trends and comparisons with the monthly normal still work, because they use readings from the same station.