I enjoy speaking on pond management and teaching its fundamentals. One of the ways I begin my talks is to let people know: It’s not always pond management, it’s often people management. People, their effects on the input to the pond, and their expectations of what the pond can do for them are the things I deal with the most. Contrasting uses for a pond can result in frustration. Actions have reactions, and finding out the root causes for a pond’s behavior is the key.
Ponds aren’t mysterious; they are behaving exactly as they should, based on their circumstances, and are actually pretty predictable. As with a lot of things, there are fundamentals to any subject and focusing on them as you begin is a good idea. A few “big picture” fundamentals on pond behavior:
Ponds are aging and trying to turn into land. As a part of natural succession, ponds generally are filling and losing volume to plant life and organic material. Some are doing this slowly, but some ponds seem to be transforming rapidly before our eyes on a seasonal basis. Each season ponds receive input from the watershed and environment: leaves, grass clippings, thatch, water runoff, erosion, and manure from fish, waterfowl, and livestock. The ecosystem digests this liquid compost, but generally not to completion each year, leaving residual organic sludge in your pond. As the volume of sludge builds over the years, it provides a bank of nutrients for the ecosystem, and creates chemical and biological demands on oxygen in the pond.
Pond ecology needs oxygen. There are two sources: mixing from weather, and photo synthesis. Submerged plants and algae provide oxygen through photosynthesis during daylight hours and respire at night, consuming some of the day’s oxygen and producing carbon dioxide. Wind, and rain and the resulting energy from wave action help to mix ponds and bring water in contact with the atmosphere for some healthy “breathing action.”
Ponds make well-defined temperature layers in the warm season. In warmer months, sunlight heats water near the surface. In addition, sunlight has limited penetration into the water column, and increases the production of single cell algae, called phytoplankton, darkening the surface water to a familiar green tint. The dark water further limits the penetration of sunlight.
There is a well-defined split in temperatures below this zone and the bottom waters are much cooler. If you have ever gone swimming in a pond as a kid or as an adult, you have experienced this refreshing change in temperature as you dive deeper. While the temperature is refreshing, this bottom water is separated from the atmosphere and oxygen levels plunge. Since fish need oxygen, fish habitat is limited to the upper layers. The lack of oxygen also has a negative effect on the liquid compost at the bottom of the pond. Just as you turn your compost pile to increase oxygen to continue processing the organic material, liquid compost or sludge in your pond reacts the same way. Processing stops in the absence of oxygen and a seasonal buildup of sludge occurs.
You see, ponds are very predictable. People on the other hand…
Keep your standards and lower your expectations… maybe. You may be able to produce a healthy crop of fish in a one-acre pond that can provide food for your family as well as recreational enjoyment. You may not, however, be able to grow a record largemouth bass, or expect that the pond will not grow undesirable plants from time to time.
Choices have consequences. You may choose to enjoy your pond as an attraction for waterfowl, domestic and wild. The manure from a large population of waterfowl on a pond can negatively affect water quality for fish and recreational swimming and prematurely age your pond. Likewise, allowing livestock direct access to the pond for drinking water can have a similar result on water quality, and challenges with erosion as well.
Even the best of friends or family can disagree about the priorities for water use. For instance, excessive irrigation can lower water levels in drier weather, and if the pond has other priorities, (fish, aesthetics, swimming), then there is going to be a conversation about the conflicting use.
Ponds make people passionate. Uncertainty about the biology of a pond, and excitement about addressing this part of the landscape, can make for strong opinions and knee-jerk reactions.
Control freaks certainly will go through a period of personal growth when they attempt to manage a pond like a swimming pool. There are things you can do to encourage the behavior you desire and discourage the behavior you don’t like. Ponds, however, are not swimming pools. They are a complex system of biology and they respond better to steering than control.
Working with the biology, having practical expectations, and knowing what the goals and priorities of your pond will help you enjoy your pond for years to come.
Next time I will talk with you about four things you can do for your pond during the fall when things seem to be calming down.