Current Approaches to Lake Restoration
Presently, there are 3 primary approaches to removing sediment from a body of water. Each of these
methodologies has limitations which prevent wide application of their respective approach.
(1) Excavation from the Basin- This approach begins with draining the water out of the lake, allowing the basin
to dry, and then employing conventional heavy equipment to remove the sediment from the lake basin.
Historically, this was perhaps the first method of dealing with sedimentation, but it does have several limitations.
Limitations:
• Drying a lake basin is very much dependent on the local rainfall. One thunderstorm can add several inches
of water to a lake and delay the project indefinitely.
• Near shore areas are the first to dry, but sediment is often present away from the shore in areas which may
never ever dry up enough to support heavy ground equipment. Often, areas of the basin in need of deepening
are left in the lake resulting in a partially deepened lake.
• Many lake excavation projects do not remove sediment from the lake. Sediment is commonly moved to the
shoreline and filled along the shore. The result is a loss of surface area and water capacity since the sediment is
redistributed in the lake basin. Lake front lots are now farther from the lake and retaining walls are often needed
to hold the sediment along the new shoreline. Installing retaining walls add considerable cost to the project.
• Because this method requires the lake be drained, lake use is lost for an undetermined time period.
• The water supply is flushed downstream and now the lake must be filled after the project by rainfall. Filling a
lake may take up to a year and if a drought should occur it can take several years. With water supplies becoming
more limited, draining a lake must be viewed as an unnecessary waste of a valuable resource.
• There is the possibility of the lake’s entire fish population being lost if a lake is completely drained.
Additional funds must then be allocated for restocking. If the lake is restocked with fingerling fish, then 2 to 3
years are needed to develop a harvestable fishery.
(2) Excavation from the Shoreline- Heavy equipment (draglines, excavators) can be used from the shoreline to
remove sediment without draining the lake. While this method is effective in some instances, there are many
limitations to this approach being universally applied.
Limitations:
• Equipment has a limited reach and often is unable to remove all of the sediment. The result is a deepened
shoreline with shallow areas in the middle of the lake.
• To operate equipment from the shoreline requires that access be established. In most cases the shoreline
around a lake has been developed with houses, yards, fences, and docks. These structures limit the extent of
dredging from the shore.
• If the shoreline is not developed, trees become obstacles and must be removed prior to deepening the lake.
This adds to the cost of the project and leaves a scarred shoreline that can take years to grow back.
(3) Hydraulic Dredging- This technique involves the use of a barge that pumps a slurry of sediment and water
through a pipe into a spoil pond. This approach is commonly used in coastal areas to remove sand from inlets,
channels, and other areas. Essential to this method is the spoil pond or impoundment area, which allows the
sediment to settle out, and the water to return to the water body. Given an adequate spoil pond location, this
method can be very efficient at moving material. However, there are some limitations to this method as well.
Limitations:
• A spoil pond is absolutely necessary for hydraulic dredging and must be located in close proximity to the
work site. In developed areas these spoil sites are not always available. In some dredging projects, land has been
purchased to accommodate this need.
• If material is to be pumped, a spoil pond must be constructed, adding additional cost to the project. The
spoil pond must be of adequate capacity to hold the quantity of sediment to be dredged and to contain the water
long enough for the settling to occur. If the pond cannot hold all the material in the project, then the project must
stop and sufficient material be excavated in order to hold the balance of material.
• Once the material is pumped to a spoil site, that site is often not the site for final disposition. Many projects
have pumped material into a spoil pond only to later come back and excavate the pond and haul away material to
the final place of disposition.
• Hydraulic dredges pump approximately 10-20% solids, therefore the pond should be located above the
water body being dredged. This is very critical when dredging small lakes as the dredge could pump the lake dry
before all material is removed.
• In order to efficiently complete large inland projects, a large dredge is needed but is very difficult to
transport from coastal areas. This results in costly mobilization fees.
Aquatic Solutions has tried these methods and recognized the limitations of present inland dredging techniques.
We sought a new way of dealing with sedimentation in a manner which could be universally applied to all water
bodies regardless of the size, location, or use of the lake.