Pond problem
Why your pond will not hold water
Work out whether it is the soil, the site, or the structure.
A pond that will not hold water is usually one of four things: the soils at basin depth are too permeable to seal, the water table has dropped below the basin so the pond is draining to groundwater, the dam or outlet structure is leaking, or the loss is not a leak at all but evaporation and seasonal drawdown. MyPond addresses the first two directly by reading the soil horizons and site constraints under the pond, and gives you the measured volume that turns "it is dropping" into a loss rate you can compare against evaporation.
Working through it
Separate seepage from the things that look like it
Evaporation alone removes a real amount of water in hot weather, and a pond with a large watershed can simply be missing its inflow in a dry spell. Before treating a pond as leaking, quantify the loss: with a measured volume and a staff gauge you can convert inches of drop into gallons per day and compare it against what evaporation can plausibly account for in your conditions. A loss rate that is steady through cool, cloudy weather is not evaporation.
Check what the soils can do at basin depth
The horizon that matters is whichever one sits at the depth of the basin, not the topsoil. MyPond reports the USDA soil horizons under the pond footprint with texture class, percent clay and saturated hydraulic conductivity for each, plus the published pond suitability and reservoir ratings. A permeable horizon at basin depth is a strong explanation on its own. Soils that should hold water are equally informative, because they point the investigation at the structure instead.
Check the site constraints
Depth to seasonal high water table and depth to bedrock decide whether the pond is perched above groundwater or intersecting it. A pond excavated below the water table is fed by it in a wet year and drains to it in a dry one, which reads as a leak that comes and goes with the season rather than a constant one.
Then look at what MyPond cannot see
Dam seepage, a failed or corroded outlet pipe, a leaking anti-seep collar, muskrat or crayfish burrows through an embankment, and tile drainage are all real causes that mapped data will not show. A loss that stops when the water drops below a particular level is pointing straight at a structure at that level. This is where a site inspection takes over, and the soil and volume data go with you as context rather than as the answer.
Where MyPond contributes
- Measured volume and surface area, so a drop in inches becomes a loss rate in gallons per day.
- USDA soil horizons under the pond footprint with permeability by layer, not just a surface texture.
- Depth to water table and depth to bedrock for the site.
- The published USDA pond suitability and reservoir ratings for the mapped soils.
- Watershed area and inflow, which says whether the pond should be refilling at all in the current conditions.
What this does not answer
MyPond works from mapped soil survey data at survey scale and from terrain. It cannot see a failed outlet pipe, a burrow through a dam, a tile line, or a seep that a soil map unit averages away. Treat it as the layer that narrows the question before someone walks the site, and not as an engineering determination on a dam.
Where the data comes from
- USDA SSURGO
- The Soil Survey Geographic database, the USDA mapping of soil map units across the United States. MyPond reads the map units under the pond footprint and their horizon by horizon properties: texture class, percent clay, silt and sand, saturated hydraulic conductivity, depth to water table, and depth to bedrock.
- USGS 3DEP
- The USGS 3D Elevation Program, a national elevation dataset built largely from airborne LiDAR at 1 to 3 meter resolution across the lower 48. MyPond samples it around and above the pond to get real ground surface shape instead of an assumed slope.
Common questions
How much water loss is normal for a pond?
Evaporation losses are real and vary widely with climate, season, wind and surface area. The useful test is not an absolute number but whether the loss persists through cool, humid, cloudy weather when evaporation should be low. Losses that continue then are seepage.
Can I tell from soil data alone whether my pond will leak?
Soil data tells you whether the soils at basin depth are capable of holding water, which is the largest single factor. It cannot rule out a structural leak, and a soil map unit describes an area rather than a boring at one point.
Does clay soil guarantee a pond will hold water?
No. Cracked, structured or coarse-fragment-rich clay transmits water faster than its clay percentage suggests, which is why saturated hydraulic conductivity by horizon is the more useful number.
Related
MyPond is built by Natural Waterscapes. See live data from a real pond, or what it costs.