Start your pump. If your pump has been off for the winter, spring is the time to start it back up. Most people do this when the water temperature increases to around 50 degrees.
Begin testing your pond water. Of particular importance are ammonia and nitrite levels. Both of these should be zero. Perform partial water changes if either test gives a reading other than zero.
Warm weather means your fish will soon be ready to start eating again. Until the water temperature is consistently above 50 degrees, continue to refrain from feeding the fish. Once the water temperature is into the 50s you will want to feed a food designed for spring and fall. As the water temperature reaches into the 60s it will be time to feed your regular summertime fish food.
Also as the water temperature reaches into the 50's it will be time to get the hardy plants that survived the winter ready for a great year ahead. This is the time we begin fertilizing the plants. Also, for maximum performance, it may be necessary to divide some of these plants. If the plants are too crowded in their pots, they will suffer and their growth and flowering potential limited.
By taking these relatively simple steps you can insure your ponds health well through the year!