Man-made lakes are generally designed to stay at least partially filled all year round. If a body of water is designed to completely dry down during the off season, it’s usually only a pond since the shallow depth makes this easier to achieve. Yet most lakes don’t receive enough rainfall throughout the year to completely replace what’s lost to evaporation and seepage. This means the lake’s water supply slowly dwindles unless there’s a refill. Manually refilling a shrinking lake from nearby wells or with tanker trucks is an expensive proposition, especially if it has to be done regularly. Finding a natural water supply or creating your own is essential for most man-made lake projects.
Damming a River or Smaller Flow
Most reservoirs for drinking water and power generation are dammed from a relatively large river. Even a smaller creek or stream can top off a smaller lake sufficiently, especially in cooler climates where evaporation is not much of a problem. There are environmental risks to damming a natural river, but if there is a need for hundreds of thousands of gallons of replacement water per day, it’s often the only choice. A drinking water reservoir can cause serious consequences if it runs down too low due to a lack of supply, so these installations require the sourcing of a steady flow first.
It’s not as easy as identifying a stream or river that you’d like to dam and purchasing the land. Since rivers have dozens to hundreds of distributary flows that would naturally allow water to reach thousands of acres of land, you must determine the total effects of damming before getting permission to do it. Your dam project for a man-made lake could dry up valuable wetlands or flood areas that are susceptible to erosion when there’s a release from the lake. You won’t be able to secure impoundment rights to a particular water source unless you have the studies to prove it will make as little impact as possible on the surrounding area and its watershed.
Digging a Well
In areas where there are no steady rivers or creeks available, or it’s impossible to secure impoundment rights for them, digging large-scale industrial wells are often the only option for keeping a lake filled. These wells can cost as much as the lake’s construction, especially if you need multiple locations drilled to reach the total pumping rate per hour for maintaining a steady water level. These wells aren’t generally designed to run constantly or automatically, but rather to be switched on manually after measurements are taken. Automatic systems are simply too risky since a sensor failure could lead to overfilling that topples a dam and causes a life-threatening flood. In addition to the upfront cost of drilling and equipment, these high-volume wells also come with monthly electrical bills for the pumps and plenty of ongoing maintenance costs. If you plan to only use a well for the initial filling, don’t shut it down right away. Keep it on standby in case a drought or dry year lowers the lake more than expected.
Constant filling, even from the largest and most reliable well, can’t make up for leaks and seepage. You’ll simply spend so much money maintaining the water level in the lake that it will never turn a profit or will serve as a constant drain on personal, business, or organization finances. Lining a pond is essential to make the most of every gallon you pump from the ground. Even lakes with abundant natural sources of water, like large rivers, still need compaction and lining to minimize water loss as much as possible. Some lakes leak so much due to seepage and cracks that even constant well pumping can’t keep the water level stable. Build, and line, the base and sides of the lake correctly from the beginning to reduce future water loss issues.
Relying on Rainfall or Snow Melt
Regions with high mountain ranges and seasonal rain patterns often rely on these massive floods of water to refill reservoirs and recreational lakes. Lake Mead, in Nevada, will often drop 15 feet or more over the course of the year and then fill back up to the original level as the snow melts in spring and early summer. Using natural and seasonal sources of water is affordable and somewhat reliable, but weather patterns can always change. This can also bring more water than the lake can hold, especially if you build to the minimum flood values for the area. Oversized lakes with reinforced dams are best for lakes that are refilled seasonally, to prevent sudden influxes of water from affecting the structure of the banks and dam.
Controlling Water Loss
All lakes will lose water if dug in sandy or loamy soil. Even when built in high clay environments where natural sealing occurs, seepage rates remain high. This translates into valuable water lost to the water table or local waterways. If the water held in the lake is contaminated and in need of treatment, you certainly don’t want it seeping through the ground to reach nearby streams or ponds. Lining a lake with geomembranes or a combination of clay and flexible liners will control water loss, potential contamination and prevent high costs for constant refilling.
BTL Liner’s ArmorPro is the ideal geomembrane for preventing water loss from a man-made lake. This durable reinforced polyethylene (RPE) liner is easy to install, fish and plant-safe, and will last for decades with proper care. Contact us today if you’re interested in using it as part of your man-made lake project.
