Farm ponds can be tricky to maintain. Soil conditions and water sources should be considered carefully in advance. A water retention problem is typically the result of too much sand and gravel in your soil. Access to a natural water supply like a creek or a stream that can help feed your pond can also be crucial to keeping the water level high enough. If you're stuck with bad soil and no waterway for continuous influx, you can use pool lining or sheets of rubber to line your pond bottom and prevent leaks and excessive drainage.
Wait for your problem pond to dry up completely before making any attempt to fix your drainage issues. Take special note of where the water pools and where it dries up fast as it drains out. Walk around the floor of the pond and examine the soil. If there is sand or gravel lining your problem areas, this is the main culprit causing the excessive draining.
Find or buy some clay or clumping dirt. Clay is the best material you can use to line your pond if it is available and/or affordable enough for you to obtain enough to get the job done. Of course, the amount you should use depends on the size of the pond you'd like to create. If you have to use dirt, avoid anything with any sand, gravel or a lot of rocks mixed in. If you can grab a handful of dirt and create a solid clump out of it, you're on the right track.
Apply your clay or dirt with the shovel and wheelbarrow, spreading it with the metal rake to make a streamlined, even surface. Use the garden hose to spray any stubborn clumps in the clay that are hard to work into an even coating. A light mist setting on your nozzle is best. Cover every square inch of the pond bottom and shoreline with a light coating first, and then tamp it down with a compacting tool or an industrial-type compacter. Use the back of the shovel to compact the dirt into any rough edges around the shoreline. Once the whole area is coated and compacted, spray a very light mist on the finished product and repeat the same process. Keep repeating until you have a durable, thick layer of very compact material covering the entire pond floor and shoreline.
Use your pool lining or rubber sheeting if you have a relatively small pond to work with and no access to impervious soil or clay to augment your poor soil conditions. Start laying the rubber from the outside shoreline and work your way toward the center of the pond floor and walk around on top of the lining as much as possible. If you have to glue strips together and don't have one continuous piece of liner for the whole pond, use your waterproof glue or epoxy to bond each strip to the next. Use heavy rocks along the shoreline to hold the liner in place while you set it in and work with it. You can move these rocks a few at a time later on and bury the liner if you prefer. Use the garden hose and fill the pond slowly, looking for bubbles that might indicate a hole, a loose seam or a tear that you'll need to fix before you fill the whole pond again.
Refill your pond completely and try to connect a close water source to it. A small stream works best for most ponds. Take the time to install an inlet pipe that you can screen or close when you need to.