Pond Boss Forums POND CONSTRUCTION Soil questions Tap into underground spring ?

Before delving into my first post, I want to thank everyone in the forum for all of the great advice you give - you are a terrific community. I only found your forum a month or so ago & it is a great resource for a beginner like me. On to my Q:

Our 1.5 acre neighborhood lake is fed by a 36" culvert of our city stormwater system which drains about 30 acres. When the water level in the lake rises to a certain elevation, there is a concrete weir at the opposite end of the lake from the culvert so that excess runoff can overflow back into the city stormwater system and eventually discharge in to the Bayou Vermilion. Well after about 20 years of residential development, silt had filled in the upper 1/3 of the lake, so the city drained and dredged out the lake. I haven't cross-sectioned it yet, but the shallow end of the thalweg will be about 7 feet deep and the deep end will be about 11 feet. There is a "shelf" of flat bank about 10-20 feet wide around the lake perimeter that will hold about 1' of water when we get enough rainfall to fill the lake up again - about 5' to go.

Anyway, several of our long-term neighbors swam in the lake as kids, and remember feeling water coming up from the lake bottom, fed by an underground spring. AAMOF, a construction job not far from here had to use matting years ago when digging ditches, because they hit the spring when digging.

Now I am not sure if the spring still exists (do they dry up?) under the lake bottom, or if we should try to tap into it. Also if we drill and hit it, would it feed our lake (potentially good) or would our lake feed the spring (bad)? Also if we were to poke through the clay into sand, we could lose water that way too.

When we have dry summers, the evaporation really drops the water level quickly & I was looking for other water sources for these dry periods. Please offer any suggestions you may have.

Thanks,
Kevin

Hi Kevin, Welcome to Pond Boss. Since I'm a bean counter I have no answer for you but hang tight and one of the PB gurus will give you answer.

Welcome Kevin,
ASMOF IMO there�s no way of knowing for certain.
A spring near the surface nearby does not necessarily mean a spring under the lake will be a positive. It�s actually just as likely to be a negative.
I would think for swimmers to feel flow under water it would have to be a heck of a spring & dredging should have uncovered it. Feeling cool water below the thermocline could possibly be mistaken for a spring.

You have to be very careful with so called springs. Springs can result from from water confined by soil or rock layers that finds a porous place where it percolates thru. If the groundwater levels are high the spring flows. If groundwater levels drop, water can leak from the lake back into the ground. Are there any wells in the area? If there are ask the owners what the water level is. It will give you a good indication of where the groundwater table is.

Thanks for the help. I guess I will leave it as-is and avoid any potential problems.

I'm also from SW LA, and concerned with the high water table in these parts. Last summer, my neighbor dug his pond 13' maximum, and it appears to be leaking. (not 100% sure, haven't talked to him lately). So I stopped mine at ~8.5 feet at the deepest point.

Welcome to Pond Boss, and good luck with the pond!