Ok I am working on a pond currently and is causing me major headaches. I am working on this pond for a client. There are 2 ponds divided by a levee. Ponds are roughly 2 acres. 1 pond he feeds roughly 20 to 30 gpm from a well using a fountain system. He wanted to feed the other pond using the fountain without moving the fountain. So we decided to put a pipe in between the 2 to let water flow and raise the level of second pond. I started by pumping 5 inches of water from main pond and then installing the pipe and turning back on the fountain. The hope was the water level would come back up and start to flow into other pond. Didn't happen. Three weeks later the water level in main pond in down 2 to 3 inches from the point I left it. No leaks around my work and no other obvious leaks around pond.

Once the pipe was put in we had 3 weeks with no rain. So I do know evaporation rates vary by the day depending on conditions. Put I figured pushing 20 to 30 gpm it would offset the evaporation. The main fed pond does have a tremendous amount of milfoil growing in it and algae and a few small willows growing along the bank. So I know this also adds to the water outtake. Any ideas to help me solve this would be great. Or in calculation I could use to try to figure out the evap and input of water would be awesome. I have came to the conclusion of eradicating the weeds from pond, possibly adding a bigger pump into the well to solve this issue.

Welcome to the forum. You can estimate evaporation by putting a 5 gal bucket or similar container with water in it near the pond, measure that and compare water loss between the pond and your container of water.

Cmm

Thanks I haven't done the actually bucket test to figure out the evap rate. But I have used formulation tables to figure out the possible rates using humidity, wind speed, water temp, and air temp. And I have roughly figured that it would take 15 gpm being pumped in to keep up with 0.3 inches a day loss by evap. But as I said the evap rate changed by the day. So I am just at a loss to get exact calculations and to see if he has a possible leak as I can't find an obvious one anywhere.

You stated that the new pipe is not leaking, so what else could be causing the pond not to gain water except evaporation?

Exactly. But I am just worried he has seepage or a leak somewhere in the pond. But I can find evidence of a leak anywhere. He has been dealing with water loss in this pond for while. By my calculations he should be ok to replace evap by adding in water from the well. So why the loss is what bothers me.

I think you need a better evap # with the bucket test.

I agree thanks. I am in the process of doing a couple of days of evap tests. Since the humidity went down and is going back up this week. Thanks for your help

I am interested in hearing what your evaporation rates are. I wish I had a well near my pond, but the cost of the well, then the cost of elec to keep the pump running.
Is your pump running on solar by any chance?
Thx
Jeff

Do't forget to put a ruler in pond too so you can get a good comparison between pond/bucket.

Bucket and pond will evaporate at different rates, fyi - it's not an exact comparison, but provides at least an idea. NOAA.gov has local evaporation rates IIRC.

Setterguy the evaporation rates varied by the day. For the most part it was around 0.1 inches most days. That was with high heat and humidity. So I think it was all due to evaporation. Because it recently rained and cooled off a little no loss. And no pump is hooked in to electric. The cost of digging the well is the expensive part. This pump runs constant but if you ever do put in a well I would suggest putting in a float system to make it cut on and off by itself. Would prob save some money.

Teehjaeh57, I looked online at noaa.gov and can't find the local evaporation rates.

I can't find them either, but a few guys have told me they are there. Figured you were more resourceful than myself...then again maybe I inadvertently provided a bad lead.

If you are trying to resolve a leak, I've worked on about 90 projects the past 18 months with 90%+ success. Feel free to ping me to review options happy to help any way I can.

Ya mean something like this?

Pan evaporation rates NOAA