From a surface of sixteen square feet, about a bucketful of water escapes every day by evaporation and transpiration of the plants. Stagnation is prevented by having a few fish and some submerged plants like Cabomba or Myriophyllum. It is therefore very easy to care for a garden up to six by twelve feet, even with only a bucket to supply water.

On the other hand, a large pond fed by a natural stream will often be in danger from floods. Unless the stream be very small in proportion to the lake it will be necessary to have means of diverting it into a culvert or sluice on occasion.

Floating parts of plants have very remarkable powers of accommodation to the depth of the water. Water-lily leaves may be entirely submerged in the evening, and by next morning their stalks will have grown just enough to spread them on the surface again. But on all considerations, it is desirable that the water level should not vary more than four inches at the most; even this amount may bring into view ugly strips of mud or masonry. An outlet of ample size is as necessary as an inlet for the regulation of the water supply.

Small ponds on level or gently sloping ground may be allowed to overflow their sodded margins. If fed by a continuous open stream, it may be most artistically led away in a similar manner, either directly, or by a waterfall, or through a bog garden.

It is doubtful whether it is easier to build a pond in a natural waterway, or to make it from the foundation up. Unless the natural water course can be easily diverted it will usually be better not to use it. For every stream at a distance of a hundred feet or more from its spring head is subject to flooding from heavy rains.

Should a violent current sweep over and among our aquatics it would destroy all the tender plants, break down our lotus, papyrus, and the like, and cover everything around with a thick layer of mud, and the season’s hopes would be gone. We shall do best, therefore, to secure a more even supply of water. A good spring will suffice for anything except Victoria and the tender waterlilies. Indeed, south of Philadelphia, spring water will materially help many of the hardy nymphaeas to endure the summer heat.

Lacking a spring, water may be drawn by a pipe or sluiceway from any near-by stream. The sluice will of course be so arranged by gates or by position of intake, as to avoid the flooding of the pond in case of freshets. But, after all, the easiest plan is to draw the water from a pipe with a spigot. It is not necessary to maintain a continuous flow and change of water. Just as a balanced aquarium will go for weeks or months without attention, so it is with the pond. It is only requisite to replace the water lost by evaporation and leakage.