Existing lakes may function perfectly for decades and then suddenly develop murky water or lose half their volume overnight. Other lakes fail from day one and require nearly a complete redesign to function as intended. Either way, there’s no reason to give up on an existing man-made lake just because it has issues. All the problems experienced by artificial lakes can be solved, although some solutions may cost far more than anyone is willing to spend. Determine if renovating an existing lake is feasible by exploring the options for repairs.
Clearing Cloudy Water
Cloudy water may be caused by algae blooms or bacterial growth coming from nutrient-rich runoff entering the lake. If this is the case, cutting drainage ditches to prevent this run-off from entering the lake, is likely your best option. When this isn’t possible, use short-term drainage basins to process and treat agricultural run-off before it can reach the main body of water. If testing reveals there are no nutrient problems, but there is a high number of dissolved solids, you’ll need to increase the settling speed of the incoming flow. Reducing erosion is often necessary to keep silt from filling the lake and making its water murky and unappealing. Look for sources of mud, soil, and silt upstream and throughout the watershed to determine what’s causing the cloudiness in your lake.
Dealing with Leaks and Seepage
A lake that has a natural bottom and has never been sealed, even with clay, will have so many individual leaks and general porosity that there’s no simple way to stop the water loss. These lakes are best drained, dredged, and re-surfaced from scratch to add a more reliable liner. Bentonite clay is a common solution for small ponds, but it rarely settles evenly enough in a deep lake to offer the same sealing benefits. You’ll likely need to drain the pond and add a geomembrane liner to leaking areas to solve long-term water loss problems.
Stabilizing Eroding Banks
Erosion will steadily fill the lake’s bottom with sediment, reduce its total depth, create muddy and murky water and eventually create leaks around the edges of the pond. There are dozens of techniques for stabilizing damaged banks; most of them involving living plants that spread out thick mats of roots to keep soil in place. Identifying the agents of erosion acting on each bank section is the first step in dealing with the problem. One area may suffer from soil loss due to high wake levels and rainfall drainage, while another may experience wind scouring and vehicle traffic. Focus your stabilization efforts on 100 to 500-foot sections of bank at a time to ensure the proper techniques are used for each area.
Rebuilding Damaged Dams
When an earthen dam gives way at a man-made lake, the project is usually abandoned due to the high cost of tearing out the old soil and rebuilding it. Dams often fail for specific reasons like unstable rock formations and unknown caves and cracks that allow for rapid water loss and underground erosion. Trying to fill in these instabilities is usually more work than it’s worth, especially if the lake can be relocated to a more suitable area. However, some dams fail in minor ways that are worth repairing. Slow, but minor leaks and seepage issues allow a dam to function without failing but still require attention eventually. These dams usually just need resurfacing or lining to restore them to the proper operation.
Creating New Spillways
Spillways are built below the dam and allow excess water to safely flow to another natural or man-made body for removal. Without proper spillways, lakes would overtop their dams and banks to disastrous consequences. Naturally, spillways are also exposed to a lot of erosive forces during regular operation. They’re usually lined with concrete for at least a short distance, but the concrete eventually breaks apart and allows water to leak under and around the intended area. Removing old concrete, placing an impermeable RPE liner above the soil and pouring new spillways can control erosion issues downstream of your lake and dam. Since water that makes it through the concrete can’t reach the soil due to the liner, there’s little chance of erosion or soil collapse to damage the new spillway.
Removing Invasive Plants and Fish
Man-made lakes provide a protected, high quality environment that is very attractive to invasive fish and plants. Even if you don’t particularly care if Asian grass carp or zebra mussels live in your lake, there’s a high risk of spreading those species to more sensitive natural waterways as you release water through your spillways. Treating invasive plant and fish species while they’re still getting established is much easier and less expensive, but many lake managers are put in charge of serious infestations. Draining the pond and treating the entire base with herbicides and fish-control chemicals like rotenone, is the best way to reset the lake and ensure there’s no spread. Even if unwanted fish species are only in small portions of the lake, full treatment is often necessary at the cost of the rest of the fish in the water.
Preparing for Fish
Fish require higher water quality and more steady flow than the other uses for man-made lakes. This is especially true if you want them to spawn and increase stock numbers on their own. Older lakes may not have the dissolved oxygen levels or pH balance to support healthy fish growth without a little extra preparation. Most lakes are large enough to stabilize their own nutrient loads, but you may need a constructed wetland to treat water exiting the pond that contains fish waste by-products. Smaller lakes likely need filtration and skimming systems to keep everything in balance year-round.
There’s no need to give up on a lake and fill it in just because it’s experiencing a few problems. Draining and renovating the bottom with a clear view of its condition is a major undertaking, but it’s still less intensive or expensive than excavating a whole new lake in most cases. When you’re ready to install a liner on an older lake, contact us here at BTL Liners for help and product selection advice.
