Your Sonar Data Is Already a Bathymetry Survey
Most lake managers are already collecting depth data without realizing it. Every pass across the water with a Lowrance, Humminbird, or Garmin unit writes a log file full of georeferenced depth soundings. That data usually sits on an SD card, gets used for a single fishing trip, and never becomes anything more useful. We built LakeTech Mapping to change that.
The new mapping tool takes the raw log files off your unit, extracts the depth and position records, and builds an interpolated bathymetry model of your waterbody. From there it derives the metrics that actually drive management decisions: total volume, mean depth, basin shape, and how the volume is distributed across depth intervals. If you have a CSV of depth points from another source, that works too.
This matters because volume is the number behind almost every treatment and design calculation in lake management. Herbicide and algaecide dosing, aeration sizing, detention time, nutrient loading models, and sediment accumulation estimates all depend on knowing how much water you are actually managing. Guessing at volume means guessing at everything downstream of it.
- Lowrance log files (.slg, .sl2, .sl3)
- Humminbird recordings (.dat, .son)
- Garmin sonar logs (.rsd)
- Generic CSV files with latitude, longitude, and depth columns
How the Model Gets Built
Once your files are uploaded, the platform parses every depth record, filters out bad returns, and interpolates a continuous surface across the lake boundary. The current release uses inverse distance weighting at a 2 meter grid resolution, which balances detail against processing speed for typical HOA lakes, reservoirs, and ponds.
The scale here is worth noting. A recent test model we ran on a 114.96 acre lagoon system used 2,009,118 survey points to populate 160,422 grid cells, and the model finished processing in 72.5 seconds. That is a level of point density no manual transect survey is going to match, and it means the contours reflect real measured bottom rather than assumptions between widely spaced sample lines.
Contours render over satellite imagery with depth labels and a vertical depth scale, so the map is immediately readable by a board member or a district engineer without any GIS software. Depth palette, units, contour interval, and map extent are all configurable at export.
- Inverse distance weighting interpolation
- 2 meter default grid resolution
- Automatic filtering of erroneous depth returns
- Contour overlays rendered on current satellite imagery
- Depth output in feet or meters
Volume, Morphometry, and the Hypsographic Curve
A depth map on its own is a picture. The analysis layer is what turns it into a management tool. Every model generates surface area, total volume, maximum depth, mean depth, and shoreline length, along with the derived morphometry indices limnologists use to characterize a basin.
Volume development tells you whether the basin is bowl shaped or flat bottomed. Relative depth indicates how likely the lake is to stratify and hold a hypolimnion. Shoreline development compares your shoreline complexity to a perfect circle, which relates directly to littoral zone extent and vegetation pressure. Dynamic ratio predicts how sensitive the waterbody is to wind driven mixing and sediment resuspension.
The hypsographic curve plots both cumulative area and cumulative volume against depth. This is the fastest way to answer questions like how much of the lake sits above the six foot contour, how much water volume you would gain or lose with a stage change, or what share of the bottom is shallow enough to support rooted vegetation. For dredging planning and sediment budgeting, it is the single most useful chart in the report.
- Surface area in acres and hectares
- Total volume in acre-feet and cubic feet
- Maximum, mean, and mean-to-max depth ratio
- Shoreline length and shoreline development index
- Volume development, relative depth, and dynamic ratio
- Hypsographic depth-area and depth-volume curves
A Report You Can Hand to a Board
Every model exports to a formatted PDF report that includes the rendered bathymetry map, the full statistics table, the morphometry interpretation, and the hypsographic analysis. The output is built for the way our clients actually use this information, which usually means attaching it to a budget request, a treatment plan, a grant application, or an annual report to a homeowners association board.
We want to be direct about one limitation. These models are generated from remotely sensed sonar and interpolated data, and they are meant for management and planning purposes. They are not certified surveys and should not be used as the basis for engineering design, permitting, construction, or dredging bid documents without independent verification. We have licensed civil engineers on staff in California who can help evaluate a model for a specific application, though a licensed land surveyor may still be required depending on the jurisdiction.
For planning work, that distinction rarely gets in the way. Knowing your lake holds 716 acre-feet instead of an assumed 500 changes your chemical budget, your aeration design, and your expectations for treatment response, and you do not need a stamped survey to act on it.
- Four page formatted PDF export
- Rendered map with contour labels and depth scale
- Full statistics and morphometry tables
- Hypsographic curve with derived metrics
- Model metadata including method, resolution, and point count
Getting a Map of Your Lake
There are two ways to get started. If you already own a compatible sonar unit, run your own survey, upload the logs, and build the model yourself. Coverage matters more than equipment quality here. Running parallel transects across the basin with tighter spacing in areas of rapid depth change will produce a noticeably better model than a few random passes.
If you would rather not run the survey, our field team collects the data for you. We map lakes, lagoons, reservoirs, stormwater basins, and golf course ponds across California, Colorado, Florida, and beyond, and we can pair the bathymetry work with water quality profiling, sediment assessment, or aquatic vegetation mapping on the same mobilization.
Either way, the model lives in your LakeTech account. Resurvey in a few years and you have a direct comparison that quantifies sediment accumulation and volume loss over time, which is the kind of documented trend that makes a dredging budget request much easier to defend.
- Run your own survey and upload the logs
- Request a field survey from our team
- Combine bathymetry with water quality or vegetation mapping
- Resurvey over time to track sediment accumulation and volume loss