June, moon, spoon...map. Nope, doesn't rhyme. But no matter, June is a good time for maps, pond maps in particular. A pond map of surface dimensions and depths will help you calculate water volume and therefore a proper aeration system design and determine fish stocking amounts. Water volume can help determine how much irrigation water will put a dent in pond levels. Mapping can help you calculate water loss due to leakage or supply/drought issues, and thus extra water to refill. Mapping can tell you how much depth and volume you've lost to sediment accumulation. Mapping now gives you a head start on the summer season, and time to cut off water quality and capacity problems.
Like other aspects of your pond (history, inflow and outflow systems, piping, water quality, etc.) mapping helps give you a good understanding of your pond, and therefore a basis for doing maintenance and making improvements.
Mapping begins with a making a couple of basic measurements: surface size and depths. Knowing these will enable you to calculate water volume. And from there, you have the knowledge needed to design an aeration system, calculate supplementary water needed to make up for water loss, and water amounts you can spare for irrigation and other uses like fire protection.
Talking to folks about their ponds, I find a lot of people don't know its size. For me, knowing surface size helps with a general idea of what's involved in water losses, algae and weed control, fish problems, etc.
Mapping surface size can be a bit tricky because most ponds have irregular shoreline dimensions. Kidney shapes, coves, peninsulas, even islands, can make mapping the surface size a challenge. Luckily for the most part you don't have to be super exact about size. It's not like you're measuring for a carpet or roof shingles. For most ponds it's often close enough to measure length and width, then multiply as for a parallelogram, and reduce a bit for the empty corners.
When I started pond work back when dinosaurs roamed the earth, I sometimes liked getting a more exact surface measurement because it then could lead to calculating water volume. And from there, combined with watershed size, runoff or flood water could be figured in to determine spillway size, either by pipe or surface channel.
Using grid paper, and some long, marked twine (with a helper at the other end), a map of the pond surface could be made. Assign size to the squares, count them up inside the pond map shoreline, and you had a good idea of surface acreage. Put that into an equation supplied by the USDA and you multiplied average depth (there's also a formula for that) by surface acreage, and you get acre-feet, which then yields gallons.
Mapping by grid was easiest in winter when you could forget the twine and helper and pace off the pond walking on ice. You could even make your own grids with footprints in snow. Now you don't even need to go outside to map the pond surface. Just click on Google maps, find your pond, delineate the shoreline, and voila, you've got surface size. Or even easier, contact an aerator company, give them your address, and they will often Google the pond surface size for you. If you can give them a rough idea of the depths, your aeration needs can then be determined. Roughly.
There are some refinements in aeration design that get the most out of those tiny bubbles. Even reclaiming depth lost to sediment. Accurate mapping of pond depths will allow you to take advantage of the most potential aeration can offer. Map variations in pond depths, as well as the composition of sediments and sludge, and learn how to aerate for the best water quality improvement, including saturated oxygen content, circulation, and de-stratification. And perhaps most surprising, dramatic reductions in sludge/sediment, which means regaining depth lost to sediment accumulation, or gaining depth from muck that was never excavated during the original build.
Depth mapping requires a boat or someone floating around on a raft or paddle-board, etc. But you can begin by making a sketch of the pond such as the graph grid paper mentioned above; or use a google map. With your map, you want to draw a line up the middle of the pond length wise (or some approximate depending on the shape), then one parallel line to the right halfway between the middle line and the shoreline, and another halfway line to the left. So, you wind up with the pond divided into thirds lengthwise.
Now comes the fun part. Using boat, kayak, raft, etc. you begin mapping the depths along each line at intervals of 10 ft or so. You can mark the lines, so you know where to do the soundings, or measure each 10 ft increment as you go.
The measurement tool suggested to me is a 1" diameter plastic pipe, marked off in feet so you can make depth notes on each sounding as you go.
Depending on the size of the pond, you can run three actual lines from one end to the other. And then paddle along each line, measuring depth every 10 ft or so. Or use a target at the end of each line for orientation, and try to stay on course.
As I mentioned a 1" diameter plastic pipe was suggested, but any sort of pole, rod, weighted and marked line, or a straight stick from the woods could do. The advantage of the plastic pipe is that it can double as a sampling tool to measure sediment on the pond bottom. Depending on the substance and depth of the sediment, you can design and use the aerator diffusers to decompose muck and possibly regain depth,
reduce nutrients that feed algae and aquatic weeds, and reduce anaerobic sludge that causes oxygen depletion, which is not good for fish and general water quality.
Jam the pipe into the sediment and close off the top to create a vacuum to keep the sediment in the pipe. When you retrieve the pipe, measure the thickness of the sediment, and its consistency. A deep layer of sediment is something to consider removing, either by excavation or slower aerator decomposition. Reducing sediment regains depth, which can translate into cooler healthier water. If the samples show that the sediment is mineral, decomposition by aeration is not likely. But removal by excavation or suction dredging could be helpful, depending on the amount of material built up.
Why June for mapping? Because if mapping reveals a situation that may call for aeration, the earlier the aeration begins the better. You can remedy poor water conditions by starting early, before algae and weeds get a head start that's hard to stop.
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