One of the most exciting projects we have going this fall is completing our garden pond. It all started when we decided to remove a pine tree that had been inconveniently placed by a previous owner of our home. When the stump came out, we were left with a hole in the ground. My partner loves to dig so much you’d think he was a badger, so he has enlarged the excavation bit by bit over the past couple of years. (At our age, shovel and wheelbarrow work has to be done in small episodes.) To begin constuction, we first establish the highest water level, then we work outward in opposite directions from that point, laying a row of cinder block to form the top edge of the pond. We have seen photos of pond construction in which the soil itself was cut and contoured. Not only is this hard work, it is difficult on a sloping site. Using cinder blocks makes the job much easier. These are "FHA" blocks, with a solid concrete bottom. Once leveled on compacted soil, they stay in place better than standard blocks.
(As the image illustrates, all construction work on the property is overseen by PJ, our Boston terrier.) It is essential to the appearance of the finished pond that the top rim be as level as you can make it all the way around. Otherwise, the liner will be visible above the water line if you leave a low spot, and this will ruin the "natural" effect. Once the top course of blocks is in place, the remaining levels can be installed using the top course as a reference.
The pond will have three levels when completed. The deepest area in the center will be kept free of plantings, and will hold the pump for a planned small waterfall. The waterfall serves not only a decorative function, but also oxygenates the water.
The second level will hold tubs planted with water lilies. We plan on using only two or three compact-sized varieties. Otherwise, the pond can become overcrowded in too short a time frame. As a rule, water lilies should be divided and repotted every three years. This can be a daunting task, as they can grow profusely in that time. On the other hand, lily pads shade the pond, which helps keep the water cool for the fish and lessens algae growth. We recommend that about two thirds of the surface be covered. The upper level is for emergent plants. These are species, such as cattails, that like wet feet but grow up from the water surface. We have dozens of varieties of such plants to choose from, and our research is ongoing. We will be posting a complete planting list here, once we have our plans completed.
The current grade slopes slightly, so we have constructed a retaining wall on the uphill side of the pond. The surrounding area will be brought up to the level of this wall and re-paved. We are using precast concrete pavers set on a gravel base. Pavers are not only easy to install without heavy equipment, they are also pervious to rainfall, and don’t interfere with natural drainage. Posts for a guardrail will be installed before paving. The wooden arch bridge in the lower right corner of the image will be replaced with a new bridge. Up to this point, it has served to get across the French drain that carries water away from this side of the house. This water will now be stored in the pond. We can re-direct the flow into another French drain when needed by means of a water gate. The excavation for the overflow is barely visible at the right of the image. It will have the appearance of a creek bed when completed and will direct water to a bed of moisture loving plants, such as cardinal flower.
The pond will now be allowed to settle for a few weeks before we install the liner. Once the liner is in place the pond will be filled with water and again allowed to settle before we begin the fun part: installing the natural stone coping and rock work. The finishing touches will allow the pond to blend with the rest of the nature inspired landscape in our back yard. We will also have "planting pockets" here and there in the rock work.We will have more to say about garden pond construction and maintenance in future posts. A small pond is a great way to put into practice the permaculture principle of increasing diversity in the landscape. Besides plants both edible and ornamental, and fish, a pond offers habitat for dozens of varieties of insects and amphibians, along with countless micro-organisms and tiny invertebrates. Properly sited, a pond can assist with water management and make great use of an otherwise marginally productive area. Using marginal areas is another principle of permaculture.