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  • Writer's pictureTallulah

How Does Dredging a Lake Work?

Dredging a lake is an important maintenance process which involves the removal of accumulated sediment, debris, and other materials from the bed of the lake. This essential maintenance activity is crucial for preserving water quality, restoring the important ecological balance, and ensuring safe navigation for the vessels which often use lakes for both leisure and commercial purposes.

Here in the UK, lake dredging plays a vital role in maintaining both the health and functionality of various water bodies, from natural lakes to large man-made reservoirs. In our latest blog post, we explore the process of dredging a lake, discuss when it is necessary, examine the potential drawbacks, and take a closer look at how The Rothen Group (TRG) can assist.

Dredging is the removal of silt and debris from a body of water to improve water quality and the environment around. Most canals and rivers need maintenance dredging, as do lakes and ponds if they are used by people. Organic sediment removal, along with litter and other natural debris, can be done by specialists like TRG who work with the environment agency and the Canal and River Trust to improve Britain’s waterways.

When TRG are contracted for canal dredging or the dredging of rivers, it is important to know which equipment can be used. TRG has a fleet of heavy equipment for any marine engineering project. Some dredging work can be carried out by diggers stationed on river banks. This depends of course on the water depth and the area that needs maintenance.

With a larger amount of water like a lake, TRG uses a floating hopper dredger to contain dredged materials prior to their safe disposal. If the lake is fed by river channels, these points can be where buildups of debris occur and so maintenance efforts may need to be focussed. The same is true of dredging a pond.

In some instances, weeds can become overgrown and cause problems for a lake’s ecosystem. Duckweed can be especially difficult as it floats on the surface of the water, blocking light to plants and animals below. TRG can help remove weeds with a combination of cutting and dredging, helping the lake’s wildlife to thrive.

The equipment used in lake maintenance of this nature includes workboats, modular pontoons, hoppers, and long-reach excavators. By making use of floating equipment stabilised with hydraulic power packs, TRG can take equipment far from the banks to perform maintenance work on parts of a lake unreachable from the bank. In certain circumstances, a trailing suction hopper dredger combined with suction pipes and submersible pumps might be used.

A hopper is a container for silt, litter, debris and organic matter like fallen leaves and branches. When a dredging project has been completed, the filled hopper is taken to a safe location where the dredged material can be safely disposed of. These disposal locations are called discharge sites.

If the silt is organic material that has not been contaminated by pollution or industrial waste, it is dried and loaded onto lorries where it is transported to farms. At the farms it is reused as a healthy natural fertiliser.

Under the silt, in many man-made lakes, is the lining. Lining is necessary to stop the water in the lake from draining into the ground. This can cause many problems that may be very expensive to fix. Lake linings are commonly made from a special type of clay, or plastic.

When maintenance is performed on any lake, pond or canal with an artificial lining, it is important that the lining remains intact. Because of this, when arranging for any type of marine upkeep, it is always best to consult with experts like TRG.

Maintenance on any body of water, be it a pond, canal, river or lake, must be undertaken regularly and to the highest standards. The issues that arise when regular maintenance is not done leads to buildups of silt and litter, blockages of waterways, and overgrowths of weeds.

Weeds can be visually very unpleasant and the bacteria that thrive in these circumstances can produce a powerful unpleasant odour. With this comes the added danger of unhealthy plant and animal life. As bacteria and weed growth continues unchecked, desirable lake plants and fish will struggle for survival and eventually die off. With proper maintenance, including dredging, this can be avoided.

Can you dredge a lake?

Yes, a lake can be dredged. Lake dredging is a complex process that involves removing unwanted materials, debris, and sediment from the lake. The process involves careful planning, experienced contractors, and specialist machinery, with the exact method dependent on the lake's size, location, and the specific requirements.

It is important to always adhere to the various environmental regulations which ensure the dredging process is conducted responsibly and to minimise potential ecological disruptions. With the expertise of professional dredging contractors such as The Rothen Group, lake dredging can be effectively and safely undertaken to preserve the health and usability of lakes across the UK.

When should you dredge a lake?

Lake dredging often becomes necessary when the sediment and organic debris buildup reaches levels that significantly impact the lake's ecological balance and the potential waterborne activities. There are some key indicators that our team always look for when deciding whether a lake requires dredging, including:

1. Reduced water depth

If sediment accumulates it can reduce the water depth, leading to shallower areas that may impede boat navigation or recreational activities. In lakes where boating or water sports are common, maintaining adequate water depth is essential to ensure the safety and enjoyment of users.

2. Water quality issues

If sediment buildup reaches excessive levels, it can degrade the water quality, causing turbidity issues, increased nutrient levels, and decreased oxygen levels, which can negatively impact the important aquatic life.

3. Loss of habitat

In addition to poor water quality impacting aquatic life, sediment accumulation can also smother aquatic habitats, impacting the health of fish, plant life, and other organisms that depend on a diverse ecosystem. Aquatic habitats such as fish spawning grounds, submerged vegetation, and natural breeding areas may become compromised. For example, the spread of algae blooms will further deplete oxygen levels, which poses a threat to fish and other aquatic organisms within the lake.

4. Flooding risks

Eventually, there will be cases where sediment restricts water flow and when combined with the risk of localised flooding during heavy rainfall, disaster can quickly strike. Reduced water flow capacity can also lead to erosion and sedimentation in downstream areas.

5. Aesthetics and property value

Aside from the immediate environmental impacts of sediment buildup, a lake with excessive debris may appear unsightly and this could potentially impact nearby property values and reduce the aesthetic appeal of the area. For example, lakefront properties rely on a clear and healthy lake view to maintain desirability and value, with regular dredging maintaining the appeal of the area.

What is the process of dredging a lake?

Before commencing any dredging operation, we complete a thorough site assessment to determine the extent of sediment accumulation, the type of materials present, and any potential environmental concerns which could impact the method used. This assessment is critical for developing a tailored dredging plan that considers the lake's specific characteristics.

This dredging plan can utilise various dredging methods, which will be dependent on the lake's size, location, and specific requirements. The most common technique for our team is mechanical dredging, although hydraulic dredging and even environmental dredging are also popular techniques. In addition, water quality management strategies are often implemented, such as sediment curtains or turbidity barriers. These measures help contain sediment resuspension and ensure that sediments settle in the designated dredging areas.

Mechanical dredging involves the use of heavy machinery, such as excavators or clamshell dredges, to physically scoop and remove sediment from the lakebed. Whereas hydraulic dredging involves the use of large pumps to remove buildups, the waste is then transported via pipe away from the lake. The most specialised method is environmental dredging which uses low impact techniques to remove contaminants with minimal disturbance to the lake.

An important element of every lake dredging process is the disposal of sediment, which needs to be transported to designated disposal sites or contained for dewatering and further treatment. Proper sediment disposal is essential to prevent recontamination of the lake and also to adhere to environmental regulations, it is also one of the most important reasons to hire a professional team.

Once the dredging of the lake is complete, our team can also complete restoration works to enhance the health, appearance, and longevity of the lake. These works could involve anything from aquatic plantings to measures which control erosion, and our team are always on hand to share knowledge and advice.

Why can dredging a lake bad?

Although there are many excellent benefits to dredging within lakes, there are situations where there could be potential drawbacks, for example:

1. Ecological disruption

There are dredging methods that can temporarily disturb the carefully balanced ecosystem, affecting fish, plants, and other organisms in the lake. The removal of sediment can expose previously buried organic matter, which leads to changes in nutrient cycling and sediment dynamics that are often carefully balanced.

2. Sediment resuspension

The process of dredging can also resuspend the fine particles in the water column, potentially affecting water quality and aquatic life. This increases turbidity which can interfere with light penetration to negatively impact aquatic plant growth and the health of submerged vegetation.

3. Cost & time

Dredging a lake can be a significant investment in terms of both cost and time, especially for larger lakes or those with extensive sediment buildup. Proper planning and budgeting are essential to ensure the efficiency and effectiveness of the dredging project, and we always advise on the most cost-effective maintenance plan.

4. Environmental regulations

Dredging operations often require compliance with environmental regulations to mitigate potential impacts on water quality and wildlife. Obtaining the necessary permits and navigating these regulations can be a complex process and if the required guidance is not followed there are negative repercussions. For example, the proper disposal of material to sites is essential to comply with regulatory requirements.

The Rothen Group – Professional lake dredging contractors

Dredging a lake is a vital undertaking to ensure its long-term health, and here at The Rothen Group we have the expertise, equipment and knowledge required to complete efficient and environmentally responsible lake dredging projects. Our team approach every project with careful planning and execution to maximise the benefits of dredging and we always support the preservation and sustainability of the lake ecosystems for generations to come. To find out more about our capabilities, services, experience, or equipment, please contact our team today.

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