When it's time to start specifying the design for your artificial lake, you'll realize that there's still another set of specs that require close attention and creative problem-solving.
Defining your vision
To begin with, you'll need a broad, moderately clear vision of your finished park and the water amenities involved. "Finished" may encompass eventual improvements and expansions as the venue grows and adds attractions, or you may choose to limit your long-term vision to a relatively simple setup that you can complete in the initial construction. Adding to a plan after the fact can be expensive and create unnecessary disruption.
Start by defining the lake's eventual purpose(s) in moderate detail, how the lake will fit into the landscape, and how the project will affect the local environment at various stages of development.
Not to get too deep in the weeds, you'll also need to plan the completed size of the lake, including average depth as well as the minimums and maximums. Consider your guests' safety, ability to perform complex tricks, ease of exiting the water in case of a wipeout, and even how you can foster good water quality.
How big will the surface area be? Length, width, shape - you must specify all of these in advance. Consider the size of your cable runs for two-tower systems as well as the necessary buffer zones for safety. How many cable systems will you use, and where will they be placed? Will you have more than one FSC? What size, how many towers, and how much flexibility can you include in the lake's design to accommodate periodic changes? Don't forget that wave break in the center of your FSC - how big will it be, and how will it look? Will it serve a secondary purpose? These details will allow you to envision the final shape of the lake and calculate the total water volume needed to fill and maintain it.
Filling the Lake
Speaking of water, manually filling a new lake from nearby wells or with tanker trucks is an expensive proposition, especially if you find that you need to top it off regularly due to evaporative loss or seepage. Finding a natural water supply or establishing your own, is essential for most artificial lake projects. When planning a wakeboard park in the vicinity of a major city, for example, you might consider digging an industrial well for the initial fill, then accepting treated stormwater from municipal authorities for periodic topping off, and eliminating seepage by lining the lake.
With an artificial lake, you can design for and essentially control the water quality in your park. Still, you'll need to plan your strategy and infrastructure from the beginning of construction. There are several levels of water quality you can aim for, each with its pros and cons.
Water resembling a natural lake may have fish, aquatic plants, visiting birds, and other appealing wildlife. Yet, fostering this kind of ecosystem in a closed, artificial lake is a risky proposition. Divorced from a complete ecosystem, your fish will produce waste, your aquatic plants may include invasive weeds, birds will add their excrement, and so on, all without any natural mitigations. Smelly green water and a slimy bottom aren't appealing, and a full-scale algae bloom is just gross. Natural-looking, lake water is an attractive option if you're going for a wholly uncultivated atmosphere. Still, keeping your water, fish, plants, and border areas in perfect balance requires intense management.
Water that contains some algae will have, at minimum, a light green color, depending on the type of algae that's present. The presence of this algae indicates there are nutrients available in the water, which supports its growth. It's important to know where those nutrients are coming from. Pale green water may be acceptable in some nature-themed aquatic parks, but algae can present many thorny problems down the road. Filamentous algae, for example, can quickly clog and damage all kinds of expensive equipment. Don't forget that algae sink to the bottom as they die, too. Suppose you occasionally forget to clean that bottom frequently. In that case, you'll soon face a slimy mass of mulm at the lake bottom which may lead to offensive odors, or even launch an ugly algae bloom. These problems can completely shut down your operation until you have it under control. However, if you can identify where any excess nutrients are coming from and eliminate the source, you may be able to control the algae cycle enough to keep your lake at the clear light green level.
Turbid water is cloudy but otherwise relatively clean. The cloudiness comes from particles stirred up from the bottom of the lake - sand, soil, residues, and organic waste. Turbidity isn't inherently unhealthy at low levels. Still, a constant stream of skiers and wakeboarders in a relatively shallow lake will agitate the water and can stir up clouds of particles that virtually never settle. The best way to minimize turbidity is to install a liner over the soil base and regularly clean your lake to remove any debris (leaves, pollen, bird waste) that has sunk to the bottom. An automatic pool vac (or several) should make that job manageable.
Clear water, of the highest quality, requires a liner to prevent the infusion of existing microorganisms or pollutants from the soil. Still, that goal also limits your liner choice to materials that do not contain dangerous elements or added chemicals intended to discourage algae or plant growth. To achieve this, a durable, UV-resistant liner certified for potable water such as BTL's Aqua Armor is the gold standard.
Outdoor facilities for water sports can maintain water nearly as clear as a traditional swimming pool, without going the intensive chlorine route, by installing an effective filtration system. One practical solution to consider is a series of gravel filter beds that trap both organic and inorganic sediment and can clear the water relatively quickly. Gravel filter beds require a system of pipes laid over the filter and several powered pumps to maintain equal and adequate pressure through all parts of the lake, so it's worthwhile to consult with a professional as you set this up. You'll need to plan for periodic maintenance, but make sure that your pipes are large enough to prevent clogging. One caveat about gravel filter beds is their reliance on natural filtration mechanisms to control algae and other microorganisms. Using chlorine or other harsh chemicals in an attempt to kill algae and sanitize the water will also destroy the beneficial bacteria in your filter beds and could start a cycle of increasing crises for your lake.
Because artificial lakes are often isolated from local waterways, they don't enjoy the passive methods employed by nature to refresh the water and prevent algae overgrowth. In addition to filtration and managing wildlife access to your lake, you'll need to develop a long-term plan to manage and stave off common water quality issues. You'll need to monitor your water chemistry regularly and have a rapid response plan to deploy in case dangerous organisms are detected in your water. You can help prevent this potential disaster by maintaining comfortable sanitary facilities for your guests, keeping pets and wildlife away from the shores, and quickly removing any garbage from the area to discourage birds and other wildlife from hanging out.
Additional Considerations for Cable Park Design
You might be able to create an artificial lake by simply digging a hole and filling it - at least temporarily. It will largely resemble the "ponds" and "lakes" you may have created as a child with a spade and the garden hose - messy, muddy, and quickly gone. Even something as simple as a backyard fishpond requires a lot more planning if you're looking for longevity and an appealing presentation.
As an artificial lake is excavated and filled with water, microorganisms will consume any leftover plant or other biological matter as it sits on the lake bottom. The decay process can take several years and may eventually cause oxygen depletion in the deeper parts of the lake. These regions of anoxic water promote the growth of sulfur-producing bacteria, which give rise to objectionable odors as they digest the decaying mess.
An artificial lake with a bare clay bed may hold water reasonably well, but it is likely to experience continuing problems with bank erosion. Erosion leads to unpleasant clouds of suspended fine particles in the water (turbidity). The energetic water movement in a cable wake park will prevent those particles from ever settling, leaving the water muddy and opaque.
Shallow lakes typically have a high surface area to volume ratio, leading to rapid warming in summer and accelerated cooling in winter - not exactly the peak experience for a year-round park. A relatively easy solution to rapid warming is the use of shade, which then presents more issues. Leaves and other debris will pollute the water while invasive roots can pierce your lining. Evaporative cooling can help improve conditions in summer, but then you'll find yourself needing to top off water levels more frequently. Depending on your climate and proposed operating calendar, installing a system to cool and heat your lake water as the seasons change may be a worthwhile investment. Alternatively, increasing the depth of your lake (within safe parameters for your guests) will allow the water to cool off as it circulates through the depths.
Surface water runoff from rain events or nearby activity such as sprinklers, car washes, or flooded storm drains can carry pollution and potentially dangerous contaminants. It should be diverted away from your lake without exception. Bypass drains and berms or other structures can accomplish this in most cases. In others, the installation of a retention pond is necessary to collect and temporarily store invading water. You can then release this impounded water back into the proper drainage channels.
Why Do Artificial Cable Park Lakes Need to Be Lined?
All artificial lakes need to be lined in some fashion, whether by compacting an existing clay soil (an arduous process that can significantly reduce the practical volume of your lake) or by installing some type of liner. In the case of a cable wake park, you'll want to seal the lake as tightly as possible to minimize seepage and prevent any influx of nutrients and fine particles from the surrounding soil. In unlined lakes, persistent (if small) wave action along the shoreline can erode and destabilize banks, leading to increased turbidity, a gradual reduction in lake depth, and even bank collapse.
All-natural lakes lose water through seepage and evaporation. On the positive side, much of that water will eventually replenish the water table, which benefits the local ecosystem. Some lakes also lose significant volume seasonally through evaporation, finally refilling with upland rainfall or snowmelt inflows. Certain lakes are more prone to water loss. Sandy soil is much more porous than clay, for example, but even ponds dug into soils with a high clay content will lose a lot of water to seepage over time. Seepage can leave you refilling your pond every few months as water slowly escapes through spaces between the soil particles.
Water exchange in the life cycle of lakes is usually self-correcting and includes both the birth of new lakes and the aging and death of old ones through a process called eutrophication. However, an artificial lake is not part of this natural system, and excessive water loss spells trouble. In the case of a significant topping-off, you'll not only need to tap into a potentially expensive source for replacement water, but you'll need to test for nutrients and other contaminants and balance your water chemistry accordingly.
In the end, liners won't solve evaporation or every water quality issue. Nonetheless, a professionally installed and carefully maintained high-quality liner can eliminate seepage and leaks from your list of concerns.