Lake guide
Bathymetric Lake Surveys
What a lake depth survey measures, what the maps show, and how they guide management.
The basics
What a bathymetric survey is
A bathymetric survey maps the depth of a lake. A boat runs planned lines across the water with a GPS linked sonar that records depth many times a second. The points become a 3D model of the lake floor, drawn as a contour map, much like a topographic map of the bottom.
The same sonar pass also records how tall and dense plants are and how hard the bottom is, so one survey produces several maps.
At a glance
- MeasuresDepth, surface area and volume
- Also mapsPlant growth and bottom hardness
- Used forTreatment dosing, aeration and dredging plans
- Repeat it toTrack sediment and plant change
The maps
What one survey shows
In the field
How a survey is conducted
Survey lines are spaced across the whole lake, closer together where the bottom changes quickly. Shallow edges and coves are covered as far as the boat can safely reach.
The recordings are processed into maps and statistics and kept on file, so later surveys can be compared directly.
The numbers
Area and volume by depth
Along with the maps, a survey reports surface area, total volume, and how area and volume change with depth.
Many aquatic treatments are dosed by water volume or treated area, so an accurate volume avoids under or over treating. Aeration is laid out around depth and shape, and volume matters for storage and drought planning.
Over time
Tracking change
Repeating a survey shows how much a lake has filled in and where, and whether plant control or muck reduction is working. Comparing surveys is also how sediment removed by dredging is measured.
Our sonar lake mapping produces depth, plant and bottom hardness maps from one survey, with before and after comparisons.
Questions
Common questions
Is a survey the same as a fish finder map?
They use similar sonar, but a survey follows planned lines across the whole lake and is processed into measured maps, volumes and statistics.
How often should a lake be surveyed?
Usually a baseline survey first, then repeat surveys to measure change after treatment, dredging or a few seasons of management.
Can plants and muck be mapped too?
Yes. The same sonar records plant height and density and bottom hardness, so one survey produces all three maps.
Sources, checked November 11, 2026. Oklahoma Water Resources Board, Bathymetric Mapping Fact Sheet. U.S. Geological Survey, Water Volume and Sediment Volume and Density in Lake Linganore.