Q. Two years ago my mom and I built a 75-gallon outdoor pond. I have recently been pondering the idea of expanding it but have been reluctant to do so because of a problem we have been having: raccoons. Every other day or so they come and attack the pond. They rip apart the water lilies beyond recognition. We have had to buy four or five new water lilies and now only one is left. The raccoons have killed horsetail, cattail, arrowhead, water lettuce, and water hyacinth. They have also killed our koi, goldfish and minnows.

We have tried ammonia, dried blood, pepper and animal repellent. We do have an enclosed yard. I have heard of using an electric fence, but that would be costly and require special wiring. Besides, we do not want to electrocute the neighborhood kids. Any suggestions you could give me would be appreciated.

A. As I am drawn increasingly into aquatic wildlife habitat work — creating and restoring them — I grow more and more impressed by the magnetic attraction that open water, especially small pools of open water, offers to critters of all types. It stands to reason that predators would eventually discover backyard ponds. Snakes, herons, kingfishers, snapping turtles and neighborhood cats are just a few of the predators I hear about routinely.

But, by my informal count, raccoons are by far the most common source of annoyance for pondkeepers. This is because they have acclimated easily to human presence and they are not afraid of water. In fact, raccoon populations in urban and suburban settings are five times greater than raccoon populations in rural settings! This is partially because they are opportunistic feeders: raccoons find garbage an abundant source of foods. Thus, you are more likely to have raccoon problems in a nice suburban development than in a rural community.

Raccoons are smart, they learn quickly, and have good dexterity — equal to that of monkeys. Lifting the lids of trash pails is no problem. Figuring out how to undo knots and other simple impediments is not very challenging.

The raccoons see your pond as a valuable source of food. They are not "attacking" your pond, but merely exploiting it. Raccoons are nocturnal (that is, they are active at night) and they are adept at using their paws to search for food when it cannot be seen. So they perch on the rocks around your small pond or on the flowerpots in the water and swish through the water trying to grab your fish or snatch the thick, starchy rhizomes of your water lilies. The damage they do is quite incidental — they would be much happier if you just left the fish lying on the ground next to the pond.

The many tricks you tried to raccoon-proof your pond should be considered a good learning experience for both you and the raccoons. They have good memories, and once they figure out how to defeat something they will be able to do it consistently in the future. Raccoons are not fooled or frustrated easily. Even using an electric fence would ultimately fail (which makes me wonder if they carry ammeters).

Outside of chaining several attack dogs in your yard at night, the best and most reliable way to end the raccoon raids is to go ahead with your plan and enlarge your pond. Yes, believe it or not, the plan you were pondering is the best solution. The photos you sent clearly show that the present design is ideal for attracting raccoons! The water is shallow, and everything (including the fish) is within easy reach or a simple jump away from a shore perch.

Raccoons will not enter water that is deeper than they can stand in. Consequently, you want to design your enlarged pond to be at least a foot deep and have the sides drop off at a fairly steep angle. You will want to keep plants and plant pots at least two feet from the edge. This will prevent raccoons from jumping to these "islands." If possible, make the rock edge around the pond steep so that it will not serve as a steady perch from which to trawl your pond waters.

The bigger the pond, the less vulnerable it will be to raccoon raids. The fish will be perfectly safe from the raccoons when they are restricted to standing on the pond edge without a good reach into the water.

Lastly, make sure that you and your neighbors lock down trash pail lids and do not leave food outdoors. Once the raccoons discover their food source has become inaccessible they will move on.

No Ducking the Problem
Q. Please help! I have a pond the size of a standard in-ground swimming pool that is 4 feet deep in some spots. The pond is in an area with a high water table and the soil is mostly clay. It receives water from a small natural stream that delivers about 25 gallons an hour. In addition, due to the high water table, there is some influx of underground water into the pond. As a result, the water is always muddy looking. Given the high water table, it is not practical to use a liner.

To make matters worse, I have 40 ducks that constantly use the pond, and they are continually drilling holes in the sides. How can I get the pond water to look clearer? How about adding a dye to the muddy water to give it a bluish color?

Also, I have added goldfish to the pond. Will they survive? That is, will the ducks eat them? I assume the pond water must contain high nitrogen levels due to the waste produced by the ducks. Because the water in the pond is so muddy looking, it is impossible to see the fish — if, in fact, they are still alive. Any suggestions would be greatly appreciated.

A. The first thing you have to decide is whether you want to have a duck pond or a fish pond. Forty ducks in what is probably between 5000 and 10,000 gallons of water is a lot of ducks. The simple fact is that the water will continue to be cloudy and silty as long as the ducks remain. It is doubtful that even lining the pond would make a difference in turbidity levels given the size of your duck collection.

You are correct in assuming that the water has a high nitrogen — and phosphorus — content due to the ducks. In terms of algae and other aquatic plants aquatic fowl wastes are nutrient rich. It is likely that part of the problem with water clarity is heavy planktonic algae growth.

The inflow of fresh water from the stream and the underground water table is simply too low to affect the turbidity or water chemistry of the pond. Blue dyes are sold to enhance the illusion of depth in ornamental ponds, or just to provide a color change. They do not affect clarity in any way. Adding a dye will merely change the water to an opaque blue rather than opaque brown. You will not be able to see your fish. It may also dye your ducks.

There are flocculating chemicals on the market that may — and I emphasize the word "may" — temporarily clear up the water. These work by gathering suspended particles in the water together. The aggregates will then sink to the bottom, clearing the water. Once the aggregates leave suspension, you have to vacuum the pond bottom to remove them or they will eventually be stirred back into suspension.

This type of chemical treatment for your size pond would probably exceed $30 per application. And, given the duck population, it would have to be repeated weekly, assuming it worked at all. On the other hand, without the ducks, this type of chemical treatment might effectively clear the water for a month or longer. Check with your local animal control office for suggestions on solving your duck problem.

Whether or not the ducks will feast on your goldfish depends on the type of ducks you have. Some species are largely vegetarian, but even that depends on the availability of the right kinds of foods. I would assume that in the absence of information to the contrary, you can take for granted that the ducks will eat the goldfish.

Let me emphasize that the problem is definitely not the natural clay lining of the pond. Clay has been used for thousands of years as the lining for artificial ponds. In fact, it was the material of choice for ancient Chinese and Japanese pond builders, who would pack it a foot thick over their excavations. These ponds can remain spectacularly clear as long as there is no extensive and continuous disturbance of the clay bed.