Glossary
MSL
MSL (mean sea level) is a tidal and charting concept: a long-term average sea surface used for nautical charts and coastal datums. Inland pool guides citing NAVD 88 or NGVD 29 are using geodetic vertical datums—not interchangeable "MSL" labels without a published tie.
Published May 16, 2026 · Editorial standards
Why it matters
Coastal anglers crossing into estuaries see chart datums based on tidal MLLW or MSL. Inland, marketing copy still says "feet above sea level." Precision matters when you blend NOAA tide products with USACE pool tables.
Technical context
NAVD 88 heights are orthometric relative to a geoid model. Tidal datums average observed tides at specific stations. They meet through national adjustment networks—but the words on the page must be read literally.
On real lakes
Related lake intelligence
Quail Creek Reservoir
/lakes/quail-creek
Explore Quail Creek Reservoir for live levels and the vertical reference published on its lake page.
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Cedar Bluff Reservoir
/lakes/cedar-bluff
Explore Cedar Bluff Reservoir for live levels and the vertical reference published on its lake page.
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Lake Monroe
/lakes/monroe-in
Lake Monroe catalogs datum NGVD29 and elevation reference MSL—compare only to readings using the same labels.
Related terms: NAVD 88 · Datum · Elevation reference · Flood stage
Reference information only. See data sources, editorial standards, or suggest a correction.