Pond Boss Forums POND CONSTRUCTION Soil questions New lake on sandy soil (existing stream bed)

Project - Building 1 acre lake 8-10 feet deep in existing stream bed fed by aquifer/springs. Normally light flow except during rains then it gets heavy.
Issue - Soil is sand w/trace of clay at depth of 12’ with water table hit at 14’ (water filled test hole to depth of 3’).
Question – Will an excavated lake depth of 10’ be sealed by the water table below or will the hydrostatic head of the lake simply drive the water table down and the lake will drain into the sand? Interestingly, the existing stream bed holds water year round at a depth of about 1 ½ feet. Lots of silt and sand.
I suspect, it will drain and my reasonable option is to seal the bottom with lot of trucked in clay.
Feedback please.

Welcome to the forum. I think your gut feeling is correct. How far below the ground surface is the water now? i.e., if you dug a hole in the ground and didn't pile any dirt around it, how far down would the water be from the surface?

My pond is like that. We dug in sand, hitting a thin layer of clay at 11'. Water was above the clay. We dug thru the clay and hit a solid band of clay at 20'. During the Spring, test holes would have water in them at 3' below the surface. I have had water levels drop around 5' from the surface. There wasn't enough clay available to seal the pond, so I have to live with it fluctuating in level, or use the well to keep it full.

With the stream running thru the pond, whatever fish are in the stream (both present and future) will end up in your pond unless you detour the stream around the pond.

Thanks for the reply. The area is Giddings Texas (between Austin and Houston on Hwy 290). Texas is currently in an epic drought so I'm pleased any surface water remains.

I plan to drill several holes (fence post auger 4" x 4' deep)and see how much (if) they fill and hold water. Any clay will have to be hauled in. I don't yet know the availability of quality clay in close proximity. I'm sure Houston has a bunch.

I want fish in the lake and in fact have nice bass in the upper area of the stream bed. The stream is divided by a low water crossing (spillway) with the elevation difference in water surface level of about 5-6 feet. The up stream is higher and spill into the lower area (my new lake site).

Do you know if a water table can/will hold water in a lake? I can drive my self crazy with senarios.

regards ray

If the water table stays high enough, yes it will hold water in the lake.