What's it take to make a lake?
In addition to the expertise that golf course designers bring to a project in civil engineering, landscape architecture, planning and agronomy (not to mention golf) we also have a major role in providing well-coordinated lake design. Most golf projects include a significant amount of water features for reasons ranging from the need to generate dirt for fill to golf strategy to providing enhanced aesthetic value. When designing a course, we attempt to balance these sometimes competing interests in a way that provides the maximum benefit throughout the life of the project.
Aesthetics and playability
In the earliest stages of a project, the design usually evolves through a series of possible routing options and proposed pond locations. When selecting the position for ponds, we are predictably looking to the low-lying or flatter portions of the property to maximize the benefit of our gravity-flow drainage systems and minimize the expense of excavation. We also derive an aesthetic benefit because the ponds will tend to have the most natural appearance if they reside in the lower spots.
With respect to playability, we try to implement several principles. We prefer to have a majority of the water to the golfer's left. This strategy recognizes the fact that most high handicappers tend to slice to the right and, by placing most of the trouble on the opposite side, we hope to avoid making the course overly difficult for the average or beginning player. We also prefer that our ponds are on the inside of the dogleg to maximize their visibility. Finally, we want to achieve a balance and variety of holes for golfers as they play the course. When possible, we avoid a layout that features a great deal of water on one of the nine holes, and none on the other nine. Our goal is to achieve a flow to the play that varies the degree of difficulty throughout the course of the round. The sequencing of holes and positioning of water are two key components in creating an interesting and exciting golf experience.
On most courses, one of the lakes will serve as a reservoir for the irrigation system, and its construction and positioning will have special requirements. First, we try to maximize the size of the lake to enhance its storage capacity. Irrigation designer Dave Davis prefers to have 4 to 7 days of emergency storage in the lake in the event that the supply of irrigation water is interrupted. Remember that to avoid vortexing (a whirlpool effect), the lake can only be lowered to within 3 feet of the pump plant intake line and, therefore, only the uppermost portion of the lake is actually providing useable storage. Also, an irrigation lake with a large surface area helps minimize the “drawdown” created by nightly watering of the course. To avoid an unsightly, muddy bank and to reduce the chances for erosion created by wave action, we try to create a lake with sufficient area to limit the drawdown to 6 vertical inches at the end of each irrigation cycle.
On sites with modest terrain (less than 80 feet of elevation change), we prefer to locate the irrigation lake centrally and lower in elevation. A central location will create the best hydraulic conditions and allow the smallest and, therefore, least expensive pipe and pump sizes. On sites with greater than 80 feet of elevation change, the lowest pond may not be a practical irrigation reservoir. The large elevation difference between the pump station and the highest sprinkler head may require a booster pump, and the irrigation designer may seek a more intermediate elevation to avoid the cost and maintenance of the additional pump.
By placing the reservoir in the lowest elevation, you maximize your ability to direct drainage to it and, therefore, capture and recycle as much rainfall as possible. In addition to conservation of water, we can derive additional environmental benefits from this configuration. Although golf course superintendents have an excellent safety record with respect to the application of fertilizer and pesticides, directing drainage through the lake network to the irrigation pond provides an additional factor of safety for two reasons:
First, any nutrients or pesticides present in the run-off are dramatically diluted when they enter the vast body of water present in a lake. The dilution is multiplied many times if the runoff actually passes through more than one lake, which is likely for runoff that originates from the more removed portions of the course.
Second, you can incorporate water-quality basins into the lake and drainage network. In these specialized detention basins, incoming, potentially nutrient-rich water is slowed to the point where excess nitrogen is taken up by emergent and aquatic plant material. Phosphorus is removed through chemical reactions with mineral-rich soil of the pond floor. Pesticides are also removed in water quality basins because they often adhere to sediment, which settles to the pond floor.
The biotic mass that accumulates in the ponds is periodically harvested, composted and may be returned to the course in landscape areas as mulch. Finally, by ultimately directing drainage to the irrigation lake, we maximize the amount of nutrients or pesticides that are returned to the course through sprinklers rather than discharged off-site. In so doing, we are, to the extent possible, creating a “closed system” that reduces the chance that an undesirable chemical reaches an environmentally sensitive area or leaves the golf course property.
Once we have the lakes positioned, our focus turns to the specifics of their design and construction. Among our major concerns are water tightness, water quality and, perhaps most importantly, safety. Golf course ponds are often referred to as “attractive nuisances” for the simple reason that they may lure people to a potentially dangerous situation. Accordingly, we must do everything possible to prevent an accident.
The best preventive measure is a modified cross section of the typical 3:1 (horizontal:vertical) slope of a lake bank. In early attempts to address the issue, designers specified a “safety shelf” incorporating a 6-foot-wide horizontal landing positioned 3 feet below the normal water level along the entire perimeter of the lake. During the course of years of experience, we have found that the resultant change in slope below water level, which often cannot be seen, may create a less safe condition than if the bottom slope was gentle and even. Therefore, the preferred approach to a safety edge has become a more gradual 4:1 or 5:1 slope from the normal water level continuing down to the bottom of the lake. The rationale of this method is that a gentle, even slope can be negotiated back to the bank by all but the most incapacitated people, and it will not provide the false sense of security that a bench might.
Water quality is also a major concern, and Rick McGuire of Waterscapers reports that it is in large part related to the quantity of oxygen and nutrients in the lake. Nutrients such as nitrogen and phosphorus are food for algae and, consequently, their presence in large quantities almost ensures the algae blooms that superintendents frequently battle.
Our strategy for controlling the problem takes a two-pronged approach. First, we try to limit the nutrients that reach the lake by circulating our run-off through the previously discussed water-quality basins. Unfortunately, we know that despite our best efforts, some nitrogen and phosphorus will inevitably reach our ponds. To manage this situation, we can introduce aquatic plants into the lake environment that will compete with the algae for these nutrients. Essentially, we are simply promoting the growth of other beneficial species to limit the propagation of the algae.
As you seek to control nutrients, you should simultaneously try to increase oxygen levels in your lakes. The presence of oxygen creates a healthy environment suitable for fish and lower members of the food chain, including microbial life. Typically, oxygen is most lacking at the bottom of a lake where the water is obviously farthest from the atmosphere. To compensate for this problem, it's beneficial to inject oxygen or ozone from specially designed tubing laid on the bottom of the lake. This configuration helps solve the problem at its source. Additionally, as the bubbles drift to the surface, they tend to pull water with them creating an upward circulation in which less aerated water is dragged to the surface, and more oxygen-rich water replaces it at the bottom of the lake. This action tends to produce a column of water that is more uniform and healthy from top to bottom.
A deeper lake also helps the oxygen interact with the lake water because the deeper the lake, the longer it takes for the air to rise in the water column and the greater the period for oxygen transfer. For good aeration, the preferable lake water depth is 15 feet, and 10 feet as a minimum.
As water becomes a more precious commodity, its conservation will become an increasingly important issue as well. To conserve water in golf course lakes, it's typical to line them with an impervious membrane to prevent leaking. PVC liners have been the material of choice for the lake industry. This material is relatively inexpensive, easy to install, durable and has a proven track record that covers more than 30 years. A PVC liner must be covered with soil, and from an aesthetic viewpoint, a soil bottom is the most desirable lake bottom surface. There are other materials that have been used in lake systems; some covered and some uncovered. But PVC continues to be the most suitable for this type of work.
As you can see, good lake design covers a range of topics and considerations. Successfully managing these factors will provide the design that creates the most cost-effective, attractive and functional lake — one that you can successfully maintain for many years.
John K. Millhouse and Richard Elliott are design principals with Sandy Lyle Golf Design (Windsor, Colo.).
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