Open Source DIY Earth Dam Design & Construction for Water Retention, Pond & Lake Creation, etc.

This page is about earth dam construction for water retention purposes. Building a small to medium-scale earth dam like the ones described on this page can provide water for irrigation, aquaculture, recreation, ecosystem restoration, and other uses. Note, we’re not experts in earth dam design. We’ve just done an immense amount of research on the topic after identifying a need for earth dams as part of the open source One Community Highest Good Housing and Food components.

We share all we’ve learned with the following sections:

• What is Earth Dam Construction
• Why Open Source Earth Dam Construction
• Ways to Contribute to this Open Source Component
• Earth Dam Construction Details
  • Legal Considerations
  • Safety Considerations
  • Sealing a Pond or Lake
  • Types Of Earth Dams
    • Valley Dams
    • Ridgepoint Dams
    • Keypoint Dams
    • Contour Dams
    • Turkey Nest Dams
    • Saddle Dams
    • Barrage Dams
  • Earth Dam Construction Steps
    • Planning
    • Earth Dam Selection
    • Initial Assessment/Siting
    • Test Slices
    • Water Storage Feature Design
    • Construction
  • Dam Construction Case Studies
• Resources
• Summary
• FAQ

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Julia Meaney: Web and Content Reviewer and Editor
Loza Ayehutsega: Civil Engineer/Assistant Civil Engineer

WHAT IS EARTH DAM CONSTRUCTION

Earth dam construction is a viable option in many places for water storage and pond or lake creation. Systems will vary from place to place, so design of your water storage feature warrants flexibility and careful observation of the surrounding landscape. The ideal solution is one that maximizes water storage and minimizes human intervention. This can be accomplished by mindfully educating ourselves on the natural elements we are working with.

The earth dam construction content here is from hours of research on this topic. Our goal is to organize what we’ve learned into some broad guidelines and hopefully turn a nebulous and daunting task into a viable water-retention solution. The overall steps of the process are outlined in the flowchart below.

Earth Dam Construction Steps Flowchart – Click to enlarge

WHY OPEN SOURCE DAM CONSTRUCTION

Dams encircle the lower perimeter of where water wants to flow to create ponds that are replenished by both surface runoff and subsurface flow. Although water tanks are preferred for drinking water, they can cost 100x more for the same amount of water stored in an earth dam. The ponds and lakes created by small earth dams also develop valuable wetland ecosystems, beautiful recreation areas, aquaculture options, and large-scale water storage for emergency and/or agricultural use. Small DIY earth dams minimize flooding during the wet season, keep water from drying up during the dry season, combat erosion, and allow the standing water behind the earth dam to better percolate into the ground, recharging the groundwater and raising the water table.

Tamera Eco-Settlement Water Conservation Results: This Took Less Than 4 years

EARTH DAM CONSTRUCTION DETAILS

Our goal with this page is to share everything our research has taught us about DIY earth dam construction. There are many different types of earth dams that you can construct, but the basics of construction are the same. The image below shows the most common earth dams and we use the following sections to discuss each of these (and others) and the ways to build them:

• Legal Considerations
• Safety Considerations
• Sealing a Pond or Lake
• Types Of Earth Dams
  • Valley or Barrier Dams
  • Ridgepoint Dams
  • Keypoint Dams
  • Contour Dams
  • Turkey Nest or Ring Road Dams
  • Saddle Dams
  • Barrage Dams
• Earth Dam Construction Steps
  • Planning
  • Earth Dam Selection
  • Initial Assessment/Siting
  • Test Slices
  • Water Storage Feature Design
  • Construction

LEGAL CONSIDERATIONS

You must be aware of and adhere to local laws before constructing an earth dam. Failure to do this can lead to forced removal of your construction. Plan ahead for this because meeting with the local watermaster, local county authority for land use permitting, fish and wildlife services, and/or the state for permission can take 6 months or more

SAFETY CONSIDERATIONS

Depending on the size and location of your earth dam, you may also need to enroll a civil and/or structural engineer in the design process. Here are a few of the things to think about:

• Consider your materials for construction. Do you need an engineer to identify if they are sufficient for your purposes?
• Consider what would happen if your earth dam were to suddenly burst and release all its stored water at once. What is downstream from that? Do you need an engineer to make sure this will not happen?
• Consider the permeability and slope of your land. Could the water you are storing cause a landslide? Do you need an engineer to make sure this will not happen?

These and any other safety concerns need to be thought of and addressed from the beginning.

It’s a scary business, it’s scary designing, especially when a lot of dirt’s been moved and sheets of water are spreading across the landscape. That’s scary. And if it scares you too much, get someone in to do it.
~ Bill Mollison ~

SEALING A POND OR LAKE

Typically, 1.6 to 3 feet (0.5 to 1.0 meter) of clay is needed to seal an earth dam. The pond water level naturally fluctuates, resulting in periodic wetting and drying of the pond bed. When the bed is exposed and not submerged under water, the clay layer can crack as it dries and these cracks can go down about 1.6 feet (0.5 meters), so 3 feet (1 meter) is ideal to account for this natural cyclical process.

When enough clay is not available at the site of the pond, we must consider other alternatives to seal the pond bed. The benefits of having a pond for water storage outweighs the use of non-natural materials that may be needed. If a pond is leaking, these methods can be tried – ideally in this order for minimum effort:

• Gleying – sealing with organic material, either with a layer of mashed, green, wet plant material or by allowing cows, ducks, and other farm animals to graze within the pond bed. The bed becomes compacted by their hoof action and as the manure decomposes, it forms a material that naturally seals small cracks. The basic process entails having a layer about 6-9 inches deep of green organic material (either plant or manure) over the pond bed (base and sides) and then covering this layer with soil, cardboard, plastic, etc.. The trapped material begins to decompose anaerobically. In cold areas, allow 1 to 2 weeks. In tropical areas, allow 1 to 2 days. Once the process is complete, remove the layer used to cover the organic material.
• Imported clay – this is an expensive option. The imported clay can be spread and rolled 9 to 12 inches thick over the entire pond or the area with the potential leak.
• Bentonite – bentonite is a clay-powder from volcanic ash that swells when watered and it is this swelling action that seals a pond. When applying bentonite, start with a nice bowl shaped pond with 30 percent slopes and ensure that the surface of the pond bed is rock-free. Then, spread bentonite out thickly and place 1 foot of rock-free soil on top of the bentonite and role it in.
• Impregnated geofabric – When using bentonite impregnated geofabric, start with a nice bowl shaped pond having 30 percent slopes and trench all the way around the outside. Lay out the fabric and put bentonite on the overlapping sections and gravel in the trench to hold the fabric in place. Place 1 foot of rock-free soil on top of the fabric and role it in. Once the water hits the fabric, it swells up and forms a seal. These come out like a natural swimming pool, they don’t muddy up at all.

TYPES OF EARTH DAMS

There are many different types of earth dams you can construct. This table shows the most common types.

Types of Dams – Click to enlarge

Here are all the good locations we could find for each of the above using a topo map, Google Earth, and 1-square-mile parcel of land.

Note: The Photoshop topo overlay in this image is not as accurate as the Sketchup overlays above and below.

We explore each of these (and a few others) with additional notes and more specific imagery below.

VALLEY DAM

Valley Dam Placement – Click to enlarge in a new window (2 MB)

Valley earth dams are constructed across a valley or gully. These dams, sometimes called a “barrier dam,” are most frequently used as energy systems. Especially when built in the path of a flowing or intermittent stream bed. These dams are also valuable for storing large volumes of water, as well as for irrigation. For these dams, it is particularly important to over design the spillway and accommodate any fish passage that has been obstructed due to dam installation.

RIDGEPOINT DAMS

Ridgepoint Dam Placement – Click to enlarge in a new window (1 MB)

Ridgepoint earth dams are located on flattened portions of descending ridges and are quite rare. It is composed of a single, horseshoe-shaped wall. These dams are most useful for water storage and runoff collection.

KEYPOINT DAMS

Keypoint Dam Placement – Click to enlarge in a new window (2 MB)

Keypoint earth dams are located in lower country where hills transition from convex to concave. These dams are primarily used to store irrigation water and are amenable to being placed in series on descending contours. These are most appropriate for 4-12% slopes.

CONTOUR DAMS

Contour Dam Placement – Click to enlarge in a new window (2 MB)

Contour earth dams are located along hillsides where the contour widens on relatively flat terrain (slope of 8 percent or less). They are 3-sided and the front of the dam is either concave or convex to follow the contour. They are most useful for domestic livestock and aquaculture. These tend to be relatively expensive in comparison to their water storage capacity. Like keypoint dams, contour dams are amenable to being placed in series on descending contours. There is insufficient natural catchment so diversion channels or swales are essential.

TURKEY NEST DAM

Turkey Nest Dam Placement – Click to enlarge in a new window (2 MB)

Turkey nest earth dams are earthen water storage tanks best placed on the highest available site with flat ground. These dams do not capture runoff, so they must be filled with external water sources. These are much cheaper than constructed tanks, but limited to use for irrigation, where as constructed tanks can be used for drinking water as well. These dams should be at least 100 feet x 100 feet x 10 feet (providing approximately 0.6 million gallons of storage) to be cost effective.

SADDLE DAMS

Saddle earth dams are unusual because this type of land feature is rare – a saddle between two hills. These dams have two walls. These dams are most useful for fire control and ecosystem/wildlife support. This type of dam typically ends up being the highest dam on the landscape and has the potential to fill from hill runoff.

BARRAGE DAMS

A barrage earth dam is one of the least likely DIY dams you’d probably consider constructing. This is because they incorporate a large mechanical component to control gates that regulate the amount of water they store. Barrage dams are normally built near the mouth of the river and used to divert water for irrigation needs or limit the amount of water going down-stream. Water builds up behind these dams and a number of large gates are opened or closed to control the amount of water passing through. This allows the structure to regulate down-stream water while also stabilizing river water elevation upstream for use in irrigation and other systems.

Here’s a video about these commonly commercial-scale dams. It provides a good explanation of the difference in function between a traditional dam and a barrage dam.

DAM CONSTRUCTION STEPS

Here we discuss the steps for constructing your own earth dam. Again, we’re not experts in earth dam design or construction. We’ve just done an immense amount of research on the topic after identifying a need for earth dams as part of the open source One Community Highest Good Housing and Food components. We share here all we’ve learned with the following sections:

• Planning
• Earth Dam Selection
• Initial Assessment/Siting
• Test Slices
• Water Storage Feature Design
• Construction

PLANNING

Throughout the life of the project, engage in a dynamic thinking process and be flexible and receptive, allowing nature to be your guide. During the planning stage it is important to clearly define the purpose and overall desired outcomes of the project and identify the resources available. Include in your resource evaluation your financial resources, your equipment resources, the lay of the land, and personal and local knowledge base.

• Engage in a dynamic thinking process
  • Set your goal to make the land resilient and vital
  • Allow your design to change based on findings during construction
  • Nature is the ultimate guide, make experiments, use applied knowledge
• Define project goals
  • Budget
  • Water volume
  • Water uses. Ex: drinking, fire suppression, irrigation, etc.
• Identify resources
  • Potential supplies
  • Favorable slopes
  • Elevations
  • Key points
  • Local construction methods
  • Evaluate possibilities using a contour map
  • Aridity of the area – Data available from the Global Aridity and PET Database
  • Legal ramifications: Meeting with the local watermaster, local county authority for land use permitting, fish and wildlife services, and/or the state for permission can take 6 months or more.

EARTH DAM SELECTION

When working with nature, it is imperative to have a variety of applications that serve the same or similar end uses. With a water retention landscape, it is wise to have a mixture of earth dam types to meet your end-use needs. This is safer and usually easier. It also better prepares you for unpredictable natural events, such as seasonal and intraseasonal extreme weather variations. To select the appropriate number and types of earth dams, the following table can be utilized:

Dam Types, Uses, and Examples – Click to enlarge

Here are some additional guidelines:

• Observe the existing patterns of water movement
• Assess climate and topography to determine water potential
• Seek to work with and amplify the site’s natural characteristics
• Assess prevailing winds – they increase losses due to evaporation
• Aim to have multiple earth dam types to serve a variety of end uses
  • High potential-energy dams: located high up, such as keypoint and ridgepoint dams
  • High water volume dams: located on gentle slopes, such as valley dams
• Maximum value for money and effort spent is achieved when the resulting length of water retained behind the earth dam is 3x the length of the dam wall

INITIAL ASSESSMENTS/SITE SELECTION

It is crucial to have soil with sufficient clay content for the earth dam structure, as well as the pond bottom. Soil with at least 40 percent clay is necessary to build a water-tight earth dam, and to retain water in the pond. Given the importance of this criteria, it is worth the money to rent an excavator to dig and evaluate the soil at the potential earth dam sites identified in the step above. The “Taking Test Slices” section below discusses how to do this.

Use models and small experiments to more deeply understand the local landscape’s potential for water storage. It is very hard to work with free-draining soil (deep or coarse sands), rocky areas, and/or areas too steep or unstable. The bottom of gentle slopes are usually better choices.

If clay has to be brought in (versus mined on your own property), rethink the pond location and/or water storage method.

TAKING TEST SLICES

Taking test slices helps you understand the types of soil you will be dealing with. Using an excavator (if available), assess the geology 6 to 12 feet below the ground surface at around 6 different locations. You can go as deep as 15 feet, but beyond that returns diminish. Dig until an impermeable layer is reached near the depth you want your pond to be. This article called “soil permeability” explains well what you are looking for and why.

The geology can be significantly different just 30 feet away. In some areas it is helpful to have the excavator put each scoop in sequence so each layer can be assessed for clay content. The excavated materials (called the “overburden”) may need to be sorted to arrive at the correct clay content. Forty percent clay or more is the goal. If you don’t have 40 percent or more clay, another area on the property may need to be mined. The video below shows how to test and measure your clay content.

Note: For earth dam construction, it is preferable to use test slices over coring. This is because coring typically only provides an assessment for the first 3 feet below the ground surface and you are seeking to assess your soil between the depths of 6 and 15 feet.

WATER STORAGE FEATURE DESIGN

Earth dams may not be the ideal solution for all locations and there are many different kinds of earth dams (see “Types Of Dams” above). Here are the key guidelines our research identified:

• Seek to minimize earth dam size
• Seek to maximize water retention
• Look at the resources you have
• If you have a valley, pick the narrowest point
• Minimize earthwork and disturbances/maximize undisturbed areas
• Use models and small experiments to test your ideas before starting construction
• Keep your thinking process dynamic/be open to change
• If you have to bring in clay, then rethink your pond location and/or water storage methods
• It is ok for your earth dam and water reservoir to leak, because subsurface and surface runoff are filling the pond
• If using your pond for fire suppression or irrigation, place the pond 100-250 feet above your area to irrigate/protect so it can function without electricity. For fire suppression, talk with the fire department to outline the exact place, including access and fittings.

Sepp Holzer uses a water-retention-landscape style where the surrounding forest is your water reservoir. Water from your dammed area spreads through the surrounding ground and helps develop a lush landscape. The picture and video below are about one of Sepp’s earth dams and the landscape like this that he created.

Tamera Eco-Settlement Water Conservation Results: This Took Less Than 4 years

CONSTRUCTION

A successful water retention landscape can be created using basic principles and well-established parameters. At a minimum, a water retention landscape is comprised of earth dams, embankment ponds, spillways, and erosion control interventions. On some landscapes, sediment traps, diversion drains, and swales make sense. In simple terms, assure that the local soil has at least 40 percent clay, all earth dam walls can be less than 20 feet (6 meters) high and still meet minimum volume/end-use requirements, and that the pond length behind the earth dam is at least 3 times longer than that earth dam’s length. An expanded array of details is provided in the image and text below:

Summary of DIY Earth Dam Components – Click to Enlarge

Below are our notes taken regarding the main features shown in the image above:

EXCAVATION

• It’s a good idea to strategically place excavated material in locations where they will be used.

“Wherever you are doing earthworks, you need to carefully remove the topsoil and not conglomerate topsoils and subsoils together. It’s taken 100s or 1000s of years to make that topsoil, you’re not going to make it again too easy. Separate it and then make your shapes and forms.”
~ Geoff Lawton ~

EARTH DAM STRUCTURE

• With 10-foot (3-meter) high earth dams made of 50 percent clay, there is confidence in the structural stability. We came across statements that 40 percent clay content is also good and can go as high as 20 feet (6 meters) tall without consulting an engineer. We’d always suggest an engineer though.
• Keyway should tie into the parent clay layer to cut off subterranean water flow and may need to go 13 to 23 feet (4 to 7 meters) down, but any deeper could cost the job. Meaning, if there isn’t clay after you have dug 23 feet, then it could be too costly to keep digging and you should consider exploring alternative methods and/or other ways to seal the pond.
• Inside wall should have at least a 1:3 slope.
• Outside wall should have at least a 1:2 slope.
• You can build your earth dam slightly concave for added stability and the earth dam will naturally take that shape over time.
• Suggested to have your crest wide enough to drive a tractor across it.
• Top dress the earth dam wall from the waterline on the water side, over the crest and down the entire backside. This adds a layer of healthy, organically rich soil that plants can grow in, which adds stability to the system.
• A lot of water builds up on the back of a dam, typically saturated, with lots of potential to support plant growth. Be prepared to be ready to seed when earth work is done.
• Plant vegetation with shallow roots (such as bamboos and grasses) and avoid deep-rooted and water-hungry plants. Bamboo sits well on the back of the wall, and on the water side of the wall above the freeboard, as well as the opposite side of the dam. Avoid plants with taproots, like acacia. Bamboo is also a natural weed preventer, as you will only find bamboo leaves that are slow to decompose and high in silica around bamboo groves. You want to keep plants around the dam small, if it is too big to take down with a machete and a chainsaw is needed, then you have let it go too long, and need to remove asap.
• When stripping the top soil off, hold it as high as possible, because it is easier to move the soil downhill as opposed to pushing it uphill when redressing the dam wall to plant stabilizing vegetation.
• When moving earth, you have to do something with the roots – they are massive and hard to move with conventional farm equipment, so it is important to move when earth movers are there. One option is to just mound the roots and paper mulch all around the roots, and plant pioneer and hardy trees around the mound, and then plant perennial ground cover that is easy to maintain, like legumes and sweet potatoes. This gets stumps out of the way so you don’t accidentally run into them when trimming and mowing the property. The mound of roots get an entire ecosystem going on their own. a whole lot of habitat developed in the roots. Another option is to have an old stump in the middle, and trim around the stump. If the stump happens to be hollow, you can fill up with good soil, and plant avocado. Avocado likes 4 feet of well-drained soil. Overtime the stump degrades.

MATERIAL USED TO BUILD EARTH DAMS

• Build with material that is slightly damp. You should be able to make a ball with it that holds together and does not expel water.
• If possible, start your project when your soil has the right moisture, otherwise build during the dry season and bring in fire trucks for water.
• Avoid: anything larger than an orange, logs, top soil, and/or clumps of grass.
• If good clay-content material is limited, use the best material on the water side and not-so-good material on the back side. The water side of the earth dam needs to be watertight, but the outside of the earth dam does not.

KEYWAY

• Track roll the earth dam keyway and wall every 200 mm (7 inches). The basic process is to lay out soil about 200 mm in depth. Then to pass over the soil again and again until depth is about 6 inches (150 mm). If using a sheepsfoot roller, this takes somewhere between 6-12 passes at a roller speed of 2-4 mph (3-6km/hr). This Manual on Small Earth Dams (PDF) has information on compaction requirements on Page 63 and says the following: “Farm machinery (e.g. tractor tires filled with water following a staggered track or small rollers) and hand methods are usually only sufficient to successfully compact layers 3 to 4 inches (75-100 mm) deep. Heavier plant such as sheepsfoot rollers (ideal for clayey soils), vibratory and smooth wheeled rollers (ideally for sandy soils) can work with layers up to 200 mm thick and obviously are preferable where large quantities and widths require compaction.”
• Since you are compressing, you will need more soil than you think.

WATER FEATURE

• Search for a good clay layer, you know you have found it when the layer is hard to dig through – no tamping necessary.
• Align water feature in the direction of your prevailing winds.
• Your pond/lake can be 5 to 6.5 feet (1.5 to 2 meters) deep.
• Aim for a minimum of 3 feet (0.9 meters) freeboard.
• Your water feature can take a long time to fill up – the ground underneath has to become saturated.

SPILLWAY

• Over design your spillway, it needs to quickly get excess water away from your dam.
• Design for 1000-year storm since we are moving into severe weather due to global warming.
• Make your spillway wide, flat, and shallow.
• Build on undisturbed subsoil.
• Avoid steep sections.
• Your spillway opening should be 1.5 feet (½ meter) below the lowest point of the earth dam.

OVERFLOW

• Use an overflow pipe to keep your water level constant.
• Make sure you also have secondary overflow control.
• At least a 6-8 inch diameter pipe is recommended, not much smaller.
• Monk pipe design notes (from Geoff Lawton Permaculture 6&7 video – timestamped 6:26:00): Used as a water level control valve, as well as serving as an overflow. Blitz cement/C900 pipe/belled 90, remove gasket on straight part of joint to be able to pivot, ok if it leaks.

EROSION PREVENTION

• Maximum angle of repose for terraces is 1:1.
• Maximum angle of repose for land in contact with water is 1:2 in all directions.
• Vegetate/mulch the banks or secure with tight rows of Vetiveria zizanioides.

OTHER ATTACHMENTS

For dessert landscapes, have your silt (or sediment) trap above the main water feature.

• Can be a deep pond filled with gravel and plants with roots underground and heads above, such as reeds.
• Be sure you have easy access to your sediment trap so it’s easy for an excavator to dredge.

You can put in other attachments too. Examples are swales (tree-growing systems), ledges for plants, and/or deep-water refuge for fish in areas where water freezes.

• Diversion drains/ditches are giant earthen gutters to move water like a rain gutter.
• Swale built on permeable soils – slowing, spreading, sinking water across the landscape.

Wherever you are in the business of making swales, work out how big they aught to be, then triple it. If they’re going to be a meter wide and a meter deep, make them 3 meters – 4 meters wide, and 3 meters deep and you might hold those big events. But if you don’t, it’ll blow the lot out. If your top swale blows, then the bank goes, and all your other swales go.
~ Bill Mollison ~

DAM CONSTRUCTION CASE STUDIES

Two case studies are presented below from work completed by Geoff Lawton. These are from the Permaculture Design Course DVDs where he taught with Bill Mollison. One key takeaway from both is placing emphasis on making things very level, so water flows will soak passively and carry nutrients around the property. We’ll add our own case studies here with videos, much clearer explanations, and complete tutorials as we complete our own dam constructions as part of the 7 sustainable villages.

CASE STUDY #1

The first case study presented is Lawton’s permaculture property that he eventually sold to one of his students. The property is located North of Brisbane, Australia on the sunshine coast where it rains quite a bit. The property is 5 acres and zoned as a small farm, about half forested and half farm fields. The forested area was inaccessible because of a valley with a creek running through it. There are three creeks on the property:

1. The main creek receives 200 acre-ft of water and is located in the valley that divides the forested land from the farmland
2. The secondary creek receives about 50 acre-ft of water and is located in the forested area
3. The third creek originates on the property

Lawton completed the work successionally – taking approximately ½ of his time for 2 years. An image of the work (dams, swales, and roads) is shown in the screen capture below from the video where he discusses this case study:

DIY Dam Case Study – Geoff Lawton’s Brisbane, Australia Property

The first thing Geoff did was install a dam to gain access to the forested side of the property that was originally deemed unusable – the road over the dam is what allowed access. A serious 8-meter wide spillway was also installed that fed back into the primary stream. It was big to minimize the erosion potential to the dam wall. During big rains, 1 meter of water would go over the spillway. A pump was installed with a float and weighted foot valve to transfer water to the top of the property. The inlet to the pump was held below the water surface with a weight and off the floor of the dam with a float. The next two were placed in succession on the secondary creek with the spillway of the upstream dam feeding into the dam in series and the second dam fed into the third stream that originated on the property. Lawton believes that replacing 20-year-old growth forest with bodies of water is beneficial because life is boosted by increased water retention.

When a wet spot was noticed at the top of the property, a contour dam (also called a top tank) was installed. It was supplied partially by the road and nature strip. Its spillway drained into multiple swales on-contour that were in-series to direct the water around the farm field. This contour dam had geese and ducks, which resulted in nutrient-rich water. When water is released during the dry season, it takes a couple of days to soak into the dry ground, then it only takes a few hours to soak the land with nutrient rich water.

Then in the bottom corner of the property, it started to get boggy after about 6 months. A neighbor began complaining about this effect, so Lawton dug a trench 2 meters wide, 1 meter deep and put the excavated material on the downhill side. When earth movers hit clay in the trench, they compacted it by hitting it with the back of the bucket. This half circle pond filled quickly. After this, a third large swale was added to further disperse the water throughout the property. Lawton hand-dug 8 to 10 meters every day for about a month and the swale ended up being more accurate than the excavator.

The neighbor continued to submit complaints and caught Lawton on a technicality, which led Lawton to improve upon his design even further. Lawton was not allowed to divert any flow from the secondary stream to the third stream. This led to the addition of another contour dam on the third creek that was connected to the dam on the secondary stream using a canal (angled banks going down to a flat bottom). Two spots were picked that were the same elevation to have easy control over the direction of the water flow. The lower dam wall was extended to cover both the secondary and third creek, which created yet another pond at the third stream. Mounds and swales were used to direct extra water into the third creek and with a slight height difference and sluice gate to direct water back to the secondary stream, so no water was being diverted from there.

Beyond this work, Lawton also had small swales near the simple temporary home near the gardened (bamboo and legumes) area for kitchen flows. These swales were 2 meters across, 1 meter deep and with 2 meters across and 1-meter high mounds. Graveled footpaths were also added between the gardens off the lower-corner dug pond, where water had been pooling near the neighbor’s property. Because the footpaths were next to the pond, they were partially flooded with water. He trellised over the pond and grew trees on the mound next to the pond and used water weeds as mulch for the garden. The last addition was a ridge point dam, which was the 7th body of water added to the property. Lawton essentially confused the catchment, melded them together and while he fixed one problem, he technically caused another problem, but creatively fixed that too. In the end, Lawton achieved the goal of having 15% of the property under water.

CASE STUDY #2

The second case study was a consulting project that Lawton worked on located in Clunes, Northern Wales. It was a hilly project serving as a demonstration and teaching site. The work completed included building two dams, a large lower valley dam and a small upper contour dam.

The entire process began with a plan on a good contour map. In the lower one, a mix of bad soil and clay were found, so earth workers and their machines had to find better material elsewhere on the property, as well as blend dirt together to attain the appropriate clay-content necessary for the keyway and water-side of the dam wall. This was especially important to do because the lower dam had a decent flow and catchment area to it. Valley dams, like this one, are important to seal.

The lower dam was built with a Jetty too. Jetties have to be pre-build before the dam is filled with water. These provide a clean edge to the dam and somewhere peaceful to sit. The top of the dam was also a minimum of 3.5 meters wide so tractors and other average-sized machines could go across it to trim growth or do other work. Topsoil was placed (it is like icing a cake) on the waterline and then hydro mulched with seed (i.e. sprayed with wet mulch containing seed). The hydro mulch contained pioneer trees, bushes, and cover crops, along with organic glue and shredded paper.

The lower large dam used a large spillway swale with level sills and was installed by ripping the soil with a tilted blade on contour. All heights were checked with a laser level (laser level emitter on tripod and laser receiver – earth movers sometimes have these for rent) and considered adequate when within 10 mm. The elevations were marked before starting and double checked along the way and at completion. To achieve clear water (the clarity of a dam at best is usually weak tea type of clarity), he installed three silt trap ponds before the dam and made sure the edges were well vegetated.

This second dam was installed 20 meters above the house and acted as their water tank. A dam holding about 125,000 gallons is less than half the price of a tank holding that same volume. It is more economical to build a key point dam on top of the property.

Notable comment from this case study: It can be surprising what you find when you start digging. You never quite know what you are going to hit. If you hit a big rock and you don’t know how big it is, have the bulldozer bump/ram (as hard as he can) the rock while you stand next to the rock. If the ground shakes, then it is a floater, meaning it has a bottom and you can typically move the rock out of the way or work around it. If there is no shake, the rock is part of mother earth. Earth moving contracts usually mention OTR, which stands for Other Than Rock, because rocks are hard to deal with and hard on the machines.

RESOURCES

This page was created primarily from the information presented in Bill Mollison’s “Permaculture: A Designers’ Manual”, Geoff Lawton’s online Permaculture Design Course (PDC), and the talk by Zachary Weiss that was part of Paul Wheaton’s PDC. Here are some other resources we found helpful too:

• Article: “Soil Permeability”
• Permies.com: “Ponds” Forum
• Article: “Keyline Project Sites”
• Manual on Small Earth Dams PDF
• Join Form: Darren Doherty Regarian Workplace
• 22-video Series: Permaculture Water Design – Drought Proofing Farms
• Article About Elevated Water Being the Best Energy Storage Method
• Article: “How One Woman Made 100 Villages in Rajasthan Fertile Using Traditional Water Harvesting Methods”
• Use this page (click here) if you have a resource you’d like to suggest be added here

SUMMARY

Creating a water retention landscape is essential to securing a sustainable way of life. Life is centered around water and the strategic installation of earth dams and supporting water features provides water security. Creating a retention landscape with earthen dams serves several life-giving purposes, such as watering holes for wildlife, fire suppression, eco-system creation and support, irrigation, livestock watering, and long-term water storage within the soil. A DIY earth dam construction site currently does not exist, so that is the aim of this site. As we build our own earth dams, we will continue adding information from those experiences so that others interested in installing earth dams have access to all the essential details necessary to do so correctly and affordably.

FAQ

Q: Where have earthen dams been installed?

There is a mention of several earthen dam installation in Australia on Darren Doherty’s website, which includes Yeoman’s Nevallan, Yobarnie Farms, and Falloon’s Taranaki Farm. Andrew Millison of Oregon State University’s Ecampus mentions some implementations in the US, such as Seven Seeds Farm and Wolf Gulch Farm. Sepp Holzer also built earthen dams on his property in Tamera and Krameterhof and Geoff Lawton has built several earth dams on Zaytuna Farm.

Q: What is the best way to compact the soil?

By using a rolling compactor (or track roller). A vibrating sheet foot roller is ideal if there is any doubt about sealing a dam.

Q: How many dams should my property have?

Have as many small earth dams as are practicable scattered throughout the landscape, some up high to harness water energy potential and some down low to support livestock/irrigation.

Q: How can I be sure my soil is good enough?

A geotech engineer could be hired for $200-$2000 who could assess the soil for its clay content and give you an accurate assessment of the structural integrity of the soil that is to be used for the earth dam and pond bed. They also provide a spec sheet that can be helpful to mitigate any unpredictable legal issues.

Q: What is the most common problem with energy efficient gravity systems?

Air locks are a common problem. From Wikipedia: “An air lock (or vapor lock) is a restriction of, or complete stoppage of liquid flow caused by vapor trapped in a high point of a liquid-filled pipe system. The gas, being less dense than the liquid, rises to any high points. Flushing the system with high flow or pressures can help move the gas away from the highest point, or a tap (or automatic vent valve) can be installed to let the gas out.”

Q: What happens if the dam begins filling as it is being dug and built?

It sometimes happens that dams fill up with water naturally very quickly and that is usually fine. A dam filling slowly while you are building it is ok.

Q: What can I expect from earth workers during construction?

During construction they used a few heavy machines, such as an excavator to dig trenches and build the dams. Lawton just had to mark the area with pegs. He found that it was easier if the excavator has a 45 ram bucket (made for golf course landscaping), because it can do a lot more with less positioning. Operators are skillful people. From Lawton’s experience the process begins the same way every time – pace around first becoming familiar with how much the other knows. Use lots of pegs so they have the information they need to get the job done accurately. Let the operator know that he/she can take his time and can put shape and form for an artistic touch. They appreciate this, because most sites want them on and off quickly. A good bulldozer driver minimizes movements to those solely used for positioning. A measure of how good they are, is cubic feet of dirt moved per unit of time. To test their skill, get them to pile up soil and spread it evenly without pulling the soil backwards – this needs to be done with feel and without back-blading.

Q: What is a stew pond?

A stew pond is a pond in a cluster of three synergistic ponds. This is a concept that includes three dams – a large, medium, and small. The large and medium dam are alternated between cattle and baby fish – cattle are allowed to wallow in one of the dams for some time and then the cattle are removed and a crop is sown and young fish are introduced. While the other dam is used to grow forage for the cows. Once the forage for the cows have matured, the cows are brought back and the mature fish from the other dam are placed into the smallest of the three ponds, called the stew pond. Here the fish mature until they are ready for the kitchen.