In most regions, you can find water by digging a well. The surface of the water in the well is the level of the water table. Below that level, the soil is saturated, with all its pores filled with water.
A high water table is a blessing if you are digging a well, but a curse if you are gardening. High water tables are often found near ponds, lakes, and rivers, but may also occur away from open water. Water tables are seasonal, usually rising in the spring and falling during dry weather. The soil immediately above the water table is soggy from capillary action carrying water up in the soil.
Here are some solutions to high water table problems.
Build a Pond or Bog
If the wet spot is located in only one part of your yard, consider excavating it and letting it fill with water to make a pond. With even less effort, plant a wet spot with bog plants and have a wetland garden. Most nurseries stock a selection of bog and poolside plants.
Make a Raised Garden
By raising the soil level, you can lift the garden above the water table. Put in raised beds or just fill in with purchased soil to get the soil surface above the water. For more information, see Raised Beds to Solve Soil Problems.
Install Drain Lines
The only way to drop a high water table is to drain the water away with drain lines. To lower a water table, the drain lines must be as deep as you want the new water table to be. Water that rises in the soil to the level of the lines will be carried away.
To be effective, the drain lines must slope downhill to a place where you can dump the water. If you are near a pond or river, this might be easy. But if you are in a low-lying area, it may be difficult to empty your drain lines. Drain lines should be about 12 feet apart, depending on the texture of the soil. A network of drain lines—often in a fishbone pattern—is laid in ditches under the garden. Simple drain lines can be installed by home gardeners, but complex ones should be planned and installed by professionals to ensure they do their job. For more information, see Installing Drain Lines.