Dam and Lake Renovations and Upgrades
Can I turn my existing dam or lake into a natural swimming pond is something we get asked a lot!
The short answer is usually yes. But the long answer involves a lot of questions and answers back and forth as not all dams are created equally. Or even close to equally, as it turns out.
One of the biggest considerations is always client’s budget. While it might seem like this kind of conversion should be easy, straightforward and not very expensive that is really rarely the case. Most lakes and dams we’ve been asked to look at are big, earth-bottomed, shaped like a bowl and often filled by uncontrolled (and uncontrollable) runoff.
This can create a lot of issues that need to be considered and dealt with.
I like to think of a dam or lake renovation in three parts.
1. Filtration & Circulation
2. Water holding ability
3. Aesthetics
The trifecta will give you an AMAZING natural swimming lake.
Often the size of the existing lake or dam is just all too much for the available budget to achieve the trifecta in a big lake or dam if all three parts need to be addressed. And let’s face it. Realistically how many people actually need a 500m2 or more recreational swimming lake in their backyard? Just because there is a dam already there doesn’t mean it’s the only option.
Sometimes it’s more sensible and economical to build a stand alone, close-to-the-house, easy to maintain, purpose built human scale swimming pond for swimming and just to improve one or two parts of the lake or dam to make it more aesthetically pleasing or more suitable for your own functional needs whether that is kayaking, fishing or even just better water holding capacity for irrigation. There’s no need for an irrigation pond to be ugly.
But if you really want to know more about renovating, revamping or enhancing your existing dam or lake then read on.
2. Water Holding
Not all earth-bottom lakes and dams are created equal. Some may hold water well due to the use of mass bentonite clay, while others may experience seepage and water loss. If you’re facing water loss issues, we have the solution: lining your lake or dam.
We offer rubber based membrane liners like Firestone Geogard or Pondgard EPDM, which completely eliminate seepage loss. The simplest installation method involves emptying and smoothing the earth base, covering it with geotextile underlayment, and installing the bare liner with anchoring trenches into the surrounding bank. However, for a more natural and visually appealing result, we like to mimic nature by adding rocks and a layer of gravel or coarse sand substrate over the liner, providing both protection and a biological habitat for the water body.
For farm or water storage dams that can allow for some seepage loss and also benefit from the self-healing ability of earth bottom dam construction, we recommend using a GCL liner (Geosynthetic Clay Liner). Although some seepage losses may still occur, the GCL liner offers a much greater capacity to prevent or reduce seepage loss compared to most earth-bottom lakes and dams. Note that a GCL liner requires a minimum coverage of 250mm-300mm of gravel/sand/soil substrate to maintain hydration and protect the liner from cracking if fully dried out. This soil can be either dug out from the existing dam or brought in. Keep in mind that bringing in additional soil will result in a decrease in water depth, but using a gravel or coarse sand substrate can help resolve turbidity issues caused by the earth bottom, unless sediment laden inflows continue from surrounding runoff.
Transforming your Existing dam, lake or large pond is an exciting endeavour that involves several key elements to consider for enhancing both it’s functionality and aesthetics:
1. Filtration and Circulation
When it comes to upgrading your water body, improving water quality takes center stage. At Think Green, we recommend the Aquascape upflow wetland filter system, a perfect solution to reduce nutrient and sediment levels within the water itself. This system operates by circulating water from an intake bay/skimmer at one end of the lake, pumping it into one or more wetland filters at the opposite end. The water percolates up through a graded aggregate filter, which functions as both a fine sediment filter and a biological filter that houses beneficial bacteria. These bacteria strip excess nutrients from the water column, promoting a healthier water body. To maintain optimum health, we advise regularly adding beneficial bacteria to ensure you maintain and encourage a diversity of bacteria strains .
Wetland filters are beautiful ponds in themselves, designed with water plants, rocks, and boulders, often featuring a waterfall or stream that creates a wildlife habitat for various animals and insects. Our wetland filters are customised to suit your water body’s surface area, volume and the desired level of filtration. Typically, we recommend a range of 5% to 20% of the surface area, taking into account factors such as the intended use, existing lake biology, and size of the water body.
You should note that while a wetland filter significantly reduces turbidity (fine suspended sediment) found in earth-bottom lakes or dams, it will rarely eliminate it entirely. To further address this issue, we recommend using a cover over the earth bottom, such as geotextile with a layer of gravel or sand substrate. This additional measure will help improve water clarity.
While wetland filters are our recommended option for superior water quality, we there are other approaches to improve oxygenation and circulation. The next best of these in our opinion is bottom aeration teamed with regular beneficial bacteria applications and significant marginal planting. This is a great option for those working on a budget that doesn’t stretch to a large wetland filter (and the associated running costs), who don’t have power nearby or who don’t plan on swimming in it regularly. Some aeration pumps can feed air
down long airlines up to a few hundred metres meaning power to run them doesn’t have to be right beside the dam or lake. There are also some wind and solar powered options available too if power is even further away.
Improving circulation by adding bottom aeration is a great first step towards improving water quality and helps the bacteria work and perform much better to help break down buildup and sludge to create a healthier water body. We use and recommend Aquascape Lake Bacteria treatments for larger bodies of water like lakes and dams. They have a treatment range including general Large Lake Bacteria, Sludge Treatment and Phosphate Binder all specially designed for lake use.
Adding a lot of marginal planting can also helps consume and start to process excess nutrient in the water whilst dramatically improving aesthetics and providing home and shelter for many animals, birds and insects. In combination with some aesthetic improvements like strategic placements of rocks or a beach area, this relatively simple approach of aeration etc can dramatically improve both the functionality and aesthetics of your lake or dam over a period of time.
3. Aesthetics
At Think Green, we believe aesthetics play a crucial role in the design and construction of lakes and dams. Often, existing water bodies lack aesthetic consideration, resulting in a plain and uninspiring appearance. For instance, membrane-lined lakes can often resemble industrial dewatering sump pits, rather than beautiful natural-looking lakes. Likewise, earth-bottom variations often feature steep sides and a slippery surface, lacking the enjoyment and wildlife habitat that a more naturalistic lake should provide.
Imagine the transformation your lake or dam can undergo with the addition of a beach, rock-retained terracing with shallow shelves for water plants, masses of water lilies, rocky outcrops, or even an island. The creative possibilities are endless!
We can work on reshaping your lake when it’s empty or near empty, making the shape more interesting and enhancing aesthetics. Whether you desire a few meters of aesthetic improvement along the waterline or a complete overhaul throughout the entire lake or dam, we can fulfill your vision.
If you’re also planning to line the water body and add filtration, we highly encourage the full aesthetic treatment. Picture having your very own naturally styled lake where you can introduce fish, snorkel, or even scuba dive! Enhancing the aesthetics along the waterline allows you to enjoy the lake’s outlook, indulge in canoeing or paddling, and create a habitat for wildlife.
Let us transform your dam, lake, or large pond into a stunning and functional masterpiece, harmonizing nature and beauty in perfect balance.
So how much does all this cost anyway?
Of course it all depends on the size of the water body, your location and access to the area where the lake or dam is. Every project is individually quoted.
However, we have worked out some guide costings to help with budgeting and deciding what you’d like to focus on.
A constructed wetland filtration system costs in the range of $1500-2000 per m2 of wetland filter fully installed including intake pumps, intake bay skimmer, piping etc.
– So a smaller wetland filter around 7m2 like we use on our 5m x 7m recreation swimming ponds (20% ratio of wetland to pond 35m2 filtered for swimming) costs around $14,000.
– A wetland filter for a lake or dam of 500m2 for semi regular swimming you would need a wetland filter of at least 50m2 (10%) and you could expect it to cost about $80,000.
– And a wetland filter in say a 2000m2 lake where you want to improve water quality for aesthetics and say fishing, paddling and occasional swimming you could look at a 5% ratio – 100m2 wetland filter around $150,000.
Bottom Aeration
Bottom Aeration could start from as little as a few thousand dollars depending on the size and depth of your lake or dam. The simplest system is the Aquascape Pro Air 60 which we regukarly use in our swimming pond projects. It performs well in water up to 2.5 metres deep and each aerator unit could be packaged up for under $2k with airline a membrane diffuser and installation. The deeper and further away from power the bigger the air pump required.
Lining an Existing Lake or Dam with EPDM Liner
Lining your existing lake or dam with EPDM liner varies from $100-125m2 for an exposed liner. Double that budget range to $200- 250/m2 cover the liner with an over-layer of geotextile, gravel and some minimal underwater retaining terrace rockwork. Lots of sloped base area. To transform your lake into a fully shaped and shelved Aquascape style recreation pond/lake suitable for never-ending interesting snorkelling and scuba diving then a double the budget again to $400-500/m2 for lining and underwater terracing rockwork and gravel/sand substrate throughout.
Lining an Existing Dam with a GCL Liner
Lining your existing dam with a GCL Geosynthetic Clay Liner without any rock work varies around $150-200/m2 if covered with gravel brought in; or $100-150/m2 if covered with existing site soil from the dam itself or close surrounds.
Aesthetic Improvements
Aesthetic improvements around the waterline to make your lake or dam look more natural and like it’s always been there are best based on the lineal metres of shoreline. On a basis of an average 2.5m width through the waterline we allow 5 water plants, 1.2 tons of rock and 0.5 tons of gravel/pebble/river sand per lineal metre. Depending on the product selections and whether or not the lake/dam is already lined, expect the budget for this to be around $800-1200 per lineal metre. This part of lake renovation budget can vary a lot depending on just how far through the waterline you want us to work on and also if it is combined with also lining the lake/dam.
There are definitely some considerable economies of scale if you’re considering addressing all three of these most significant elements for
your lake or dam.
To Work out How Big is your Lake or Dam is..
To work out how big is your lake or dam a good place to start is on your local governments website page if they have Intramaps available for public access to use tools to measure it on an aerial photo. Don’t forget to add 2 x the maximum depth to both your width and length measurements when working out liner size to allow for the liner to go down to the bottom and back up. Also bear in mind that EPDM rubber liner comes in a big rectangular sheet so you only need to measure length and width of lake to work out liner required. For a GCL liner you can work out actual aerial photo area (+ depth) and add 10% as it is installed from a roll around 5m wide that is overlapped sheet to sheet and cut and overlapped to shape in rounded areas.
A full range of complementary landscape design and construction services are also available to complete the landscape and garden around your water project.
Inquiry
The Process From Here
Once we receive this form back in full, we can arrange a phone call or exchange emails to get a better idea of your needs, desires and the scope of your project to give you a guide to the expected budget range. We have built a lot of Aquascape systems in a wide variety of sizes over the last five years so have a great portfolio of projects and pricing that we can use as a guide. We’re also happy to offer guide pricing details of any of our past projects that you might have seen which is often helpful in the decision making process..
We’ll also look at your photos you send through and look up your garden on recent Nearmaps aerial photos as we are talking or emailing to get familiar with your garden and property, and what your waterscape dreams and goals are.
We offer this introduction service to find out a bit more about your project ideas and scope of work, to give you a guide to expected budget and to make sure we’re the right fit for you before you engage our services for a paid onsite consultation visit and concept plan.
What is a Think Green Consult and Concept Plan
Tony, our leader of design and operations, will visit your property and your waterscape project with you and other key decision makers. Husband, wife, kids, dog – whoever is going to be involved!
We usually charge $250 for a regular consultation visit and concept plan (in Perth area and surrounds) to assess the area, check important measurements and levels and to talk about your ideas. It’s also an opportunity for you to pick Tony’s brain for more ideas and information too. The consultation usually includes a concept sketch plan with an itemised quote and guide to timelines.
We also include the Aquascape ‘Hands of the Artist’ hardcover coffee table book (around 350 pages of Aquascape artistic water features for inspiration and ideas). As Master Certified Aquascape Contractors, one of our projects is featured in the book on page 310. (We will post the book in advance for prepaid consultations)
