Hi I recently finished a 3 acre pond on a new venue we are building for events and weddings.. It is an average of 25 feet deep at full pond. Due to amount of water in the pond, the county had me install a pretty large pipe system in case the pond needed to be drained. Something in the pipe system is allowing a leak of about 20 gallons per hour to leak through the pipe. This pipe flows 90 feet through the base of the dam, and then another 300 feet through a pasture and would drain into a large creek. The logic in this was if the pond had to be drained, the 12 inch underground pipe would allow the water to go into the creek without damaging what is suppose to be a vineyard.
The problem is, we have been unable to find the leak. There is a lot of silt on the pond and I have had a diver go down and look with no luck finding the leak. The valve is at the deepest part of the pond, about 40 feet deep, and there is a ton of silt in that area.
I have little faith in the yahoo's that built the pond can do anything, so I am kinda stuck. The pond is creek feed and when creek is running good we increase, but when it slows we decrease and have never hit full pond.
Even if we drained the pond (and lost the 3 grand of fish we put in this spring) I am really not sure we could locate the leak.

Soooo I have been thinking that the best solution might be to just recirculate the water back into the pond. I do not have electricity available and have been looking at a solar water pump to pump water back into the pond. In research I have found a pump made by Dankoff called a slow pump that can pump water long distances through 1 inch pipe.
So here is my thoughts and I would gladly appreciate any help or guidance.

Install something to collect the water, say a 500 gallon water tank,
Install the pump,water filter, and a float valve to allow the pump to come on pump the water through 400 feet of buried 1 inch pipe back into the pond. I will build a shelter over the collection tank and pump and mount the solar panels on top. Pump will probably run about 3 hours a day. I know this sounds nuts, but I have a lot of $$ in this project and we need to get this lovely pond to fill. That being said before investing another $2500 in this system I thought I would see if anyone else has an idea. We should have power to the area in 2 years and this will open up more options.

So to summarize:
Need to pump apx 400 to 500 gallons of water per day about 400 feet with a 40 foot elevation, back into a pond. No electricity available, and no one lives on the property that could come and crank up a gas pump.

Looking to install a dankoff slow solar pump and necessary components to pump water daily back into the pond.

Again I appreciate any thought on this.

Thanks