Landscape Architect Articles

LCN April 2007 Ponds, Lakes, And Waterfalls03-27-07 | News

Ponds And Lakes: Lessons From Biologists

This 7-acre water feature in Georgia contains trout that are able to forage for food rather than be overfed by a pellet system. Georgia recently suffered from an unusually warm summer, which unfortunately killed off most of its trout population. However, the trout in this lake survived due to the excess of nutrients they received from being fed naturally. Photos courtesy of Spring Creek Aquatic Concepts

Water is a very precious resource. Ponds, lakes and waterfalls bring great financial and personal value to the land. Spring Creek Aquatic Concepts specializes in creating these water features and shorelines. They design aquatic landscapes from the bottom of the pond to the upper edge of the wetland shoreline. Whether a residential pond, a private fly fishing lake, stream, shoreline or large lake of several hundred acres, an innovative practical approach will add value to the land.

Requirements

In order to have a quality pond or lake in most cases you will need roughly 10 to 20 gallons per minute of water flowing into them per acre of surface area. In other words it is possible to have trophy size fish in a pond with only a garden hose for a water supply. Typically, this amount of water is required during the hotter, summer months. Winter requirements are much lower. This is much less water than most people assume is necessary. It is often important to employ proprietary techniques from the need for more habitats on less water resource.

Water for a pond or lake may come from a variety of clean water sources such as springs, wells, streams and even surface runoff. A large proportion of new ponds are now using well water to support them. Efficient use of water minimizes water supply costs in these cases. Land is usually much less expensive when there is no stream or spring, which requires a well to support the aquatic habitat.

Biologists Design Water Features

There is a wealth of publications to help you build a pond to safely hold water. While these publications are a good place to begin, they cover only a very small portion of the factors that go into producing quality habitats.

An aquatic habitat requires a three dimensional design instead of the more two-dimensional terrestrial landscape. In a lake, the water becomes the soil. This opens a Pandora?EUR??,,????'???s box of complexity that does not have to be considered on dry land.

Exceptional aquatic and terrestrial landscapes compliment each other. A glass clear lake simply looks better reflecting against a naturally flowing landscape instead of the usual unattractive pile of rocks, or worse yet, mounds of barkdust one sees along the shorelines of many projects.

The native trees that surround this pond consist of several varieties of ash, maple and oak. Although natural streams are often a source of water for a lake or pond and its vegetation, many times regulated wells may be used. Unlike streams, wells do not pose any sedimentation threat to the nearby aquatic landscape.

Building A Lasting Pond or Lake

Well-designed man-made ponds should last for centuries. The reality for poorly designed ponds can be less than ten years due to factors such as siltation and excessive residual nutrients.

Synthetic lake and pond liner life expectancies run a couple of decades. It is an inconvenience to need to rebuild a pond after just a couple decades. Regardless of the life expectancy of a synthetic liner, many of these ponds are experiencing siltation and choking with weeds long before the liner wears out. It is not unusual for one of these poorly designed ponds to choke out with weeds in as little as five years. In most cases it is necessary to rip them out and restore them for the long term. To be fair, poorly designed earthened ponds can expect similar life expectancy, even if the clay seal will function for centuries.

Lakes and ponds should withstand the test of time. A long life expectancy results in significant property value appreciation. A short life expectancy actually depreciates.

While completing construction, soil additives were blended into a truck and sprinkled onto the native clays that were used to seal the pond. The amount of clay, usually several inches to a foot deep, depends on what threats are present in the surrounding environment, such as burrowing animals. The clay is compacted and is part of the natural selection of materials biologists often prefer to use rather than a typical plastic lake liner.

Invasive Aquatic Plants and Animals

Invasive plants are those that cause problems for either humans or the vegetation native to a particular area. From an aquatic aspect, an invasive plant might clog a lake to the point of causing the lake to become useless for human use or for the use of native plants and animals.

The easiest way to avoid the problems of purchasing invasive plants is to buy your plants from a professional nursery. In the case of aquatic plants, this usually means purchasing from a native wetland nursery instead of one that specializes in ornamental pond plants. The side benefit you may notice is that the plants are usually healthier and less expensive. There are several very positive reasons to utilize species that are native to your area:

?EUR??,,????'???? There are a wide variety of native plants available when compared to the short, unimaginative list of usual water garden plants.

?EUR??,,????'???? Native plant variety results in more colors and longer flowering seasons.

?EUR??,,????'???? Native plants will survive the winter in small garden ponds. You don?EUR??,,????'???t need to overwinter them.

?EUR??,,????'???? Your pond or water feature is now an asset to the natural environment instead of a threat.

The clarity of this water feature is the direct result of a keen knowledge of a watershed. It was able to remain clear even after surviving three hurricanes, which flooded the pond with murky water from the storms. Dirt and siltation are often the death of many water features but investing in an oxygen meter can often help measure the amount of oxygen the water is receiving thus increasing clarity.

Preservation

Ponds and lakes are especially vulnerable to pollution, even more so than streams. Ponds and lakes are great big sponges for excess nutrients and pollution. They can also have a difficult time dealing with heavy loads of nutrients generated from areas of intense human use, such as cities.

Streams have the luxury of having a lot of oxygen, which is necessary to break down excess vegetation and sludges formed by decaying plants. This is because many streams are constantly falling and tumbling which mixes oxygen from the atmosphere in with the water. Ponds and lakes are not so fortunate. During the long days of summer, a lake or pond will produce great quantities of oxygen because plants produce oxygen as a by-product of their growth, which is known as photosynthesis.

There is a price for this oxygen production in still waters. When the water cools, the sunny days of summer turn cloudy and when temperatures drop, plant growth starts to slow. Plants then begin to die-off during autumn. At this point all of the bacteria and fungi take over and try to clean up all this mess of plants. They need to breathe oxygen to clean up the dead plant material. All of the oxygen produced during summer is now rapidly being consumed. If this happens vigorously enough, an entire lake can run out of the oxygen and die!

Plants need nutrients to grow. The best way to keep your lake or pond healthy is to keep the excess nutrients out of the water. This will allow the pond to clean itself without running out of oxygen because there is only a small fraction of the plants that have to be cleaned up. Generally speaking there are two very important nutrients that make a lake unhealthy when they cause the lake to produce too many plants. These are Nitrogen and Phosphorus. One or the other will become the limiting nutrient that will cause plant growth to stop when it is not in sufficient supply.

While there are generalities to be drawn as to which of these nutrients is the limiting nutrient on a regional basis, examples have been seen where the limiting nutrient shifts back and forth within a single stream/lake complex! It is best to consider both Nitrogen and Phosphorus due to complexities of the natural environments. One always needs to look downstream to see the impact of your actions.

This is the site of one of Aqua Habitat's smaller projects located in Oregon. Some of their more natural ponds and lakes must be fertilized preventatively with organic fertilizer pellets comprised of fish meal to ensure a healthy ecosystem in which native plants and animals thrive. It is important to note that no liners were used in the creation of this lake, a clay seal was formed that allowed for a couple of inches of seepage per month, which not only makes the lake more efficient to maintain but can increase its life expectancy from years to centuries.

Protecting Lakes and Ponds

So how can you keep excess nutrients out of the pond or lake? An ounce of prevention is usually worth much more than a pound of cure in this case. The idea of creating stream, lake or pond buffer plantings around the edge of the water is very popular and productive. Preventing nutrients from flowing down storm sewers is a good way to prevent pollution.

Healthy water supplies during dry months also help keep the aquatic environment clean and healthy. Capturing rainwater from a roof and running it through the small pond will help slow the surface runoff and allow more water to seep into the ground. This ground water then emerges into the streams on a much more even basis instead of flooding the local lake. It also cools the water, which provides a better environment for cold-water fish such as trout.

Source: Spring Creek Aquatic Concepts

Water Facts

10 to 20: Gallons per minute, the ideal amount of water flow per acre of surface area for a high quality lake or pond.

100: Years or more, the life expectancy of well designed man-made ponds. The reality for poorly designed ponds can be less than ten years due to factors such as siltation and excessive residual nutrients.

16,133: Cubic yards, the amount of soil needed for constructing a one acre pond that averages 10 feet in depth.

Source: Spring Creek Aquatic Concepts