Feature 2: Low Maintenance Lake Design
With a main goal of creating a great fishing lake with low maintenance as it ages, significant thought must be given to several crucial concepts.
Low Maintenance Lake Design
By Bob Lusk
Last November, I received a phone call from longtime client and Pond Boss subscriber, Dr. Steve Beck. He’s officially retired from his dermatology practice in east Texas and wants to focus on building what he says is his “final” lake. Dr. Beck has been fascinated with fishing lakes, fish, land, and conservation for decades. He started back in the 1980s by building several lakes on his home property. There, he learned as much what NOT to do as what to do. While those lakes thrived, they had to be pushed and tugged to get them where he wanted. That’s when he learned about the importance of habitat.
Before long, he started buying parcels of nearby land, building a lake, stocking and managing, learning about the resource, and then enjoying the place. Before too many years, someone would come along, love what he did, make an offer he couldn’t refuse, and it was time to go do it again, elsewhere.
During the phone call, we made an appointment for a site visit to see what he was up to. As we talked, he made an interesting comment, one I don’t hear often. “I’d like to design this lake so it is low maintenance.” He continued, “I plan for this place to be a legacy property, to pass on to my children. I don’t want them to have to be worried about dealing with too much vegetation or having to take out too many fish, or fertilize or any of that stuff. I want to design a lake that pretty well takes care of itself.”
That’s not an easy task.
It was actually refreshing to hear someone voice that concept. Most people want to focus on the fishery, or to grow the biggest fish on the planet, or make sure their catch rates are just right, or figure out how to speed up the process of developing their fishery.
With a main goal of creating a great fishing lake with low maintenance as it ages, significant thought must be given to several crucial concepts. Job one will be to make sure the dam fits the watershed. Not only does the dam need to be the proper size, a well-engineered primary and emergency spillway will play a role. Plus, there are several places upstream where loose soil can readily flow during those huge rain events. Silt ponds are in this lake’s upstream future.
As we toured the property, Dr. Beck didn’t really want to discuss the dam or the spillway. He’s already zeroed in and confident of that process, and his earthmover is on task with it.
My job that day was to help with lake design that would lend itself to low maintenance fisheries and water management over a long period of time.
I’m going to step out on a little limb in this discussion. I’m expecting water quality, water chemistry, and soils to be healthy for a lake. I see no reason to expect anything different than good conditions at his site. But, prudence being what it is, we will pay attention to water chemistry, because if the lake basin needs liming, he might as well put in 20 years’ worth in the beginning rather than deal with it again in a few years.
The biggest emphasis for a low maintenance, successful lake with a thriving fishery is outstanding habitat, especially permanent habitat. That’s the number one focus. If we design the best permanent habitat for target species, we’ll have a lake easier to maintain over the long term. One of my favorite catch phrases is, “As goes the habitat, so goes what lives in it.”
To establish these principles, we need to understand habitat in detail. As a general definition, habitat is what fish need to be able to reproduce, feed, congregate, move about, hide, and loaf. Each species of fish needs different habitat. Some of those habitats overlap, like bass and bluegills. Some habitats don’t. Threadfin shad don’t overlap with crappie. But, threadfin shad definitely overlap with hybrid striped bass. Largemouth bass spawn in a solitary nest anywhere from 18 inches to four feet deep or deeper, and the male defends it fiercely. But, that nest may hold eggs from several different females. Bluegills, on the other hand, spawn in colonies, at a different temperature than bass. I’ve counted as many as 150 craters in a bluegill spawning colony. Redear sunfish use the same beds as bluegill, but those shellcrackers spawn at a different temperature. In warm lakes, crappie are the first game fish to spawn, moving from deep to shallow areas, often spawning less than six inches deep. Channel catfish spawn last each year, and must have a cavity to hide, or they won’t lay their eggs.
The detail really comes when we think about habitat for all size-classes of each species of fish. For example, baby bass run in schools of its nest-mates—until slightly larger predator fish burst into schools over a 4-6 week period, eating most of the fish. By then, remaining bass have grown from zero to four or five inches and are running for their lives most of the day—unless there’s dense structure where they can hide, and emerge long enough to eat something slightly smaller. 10-14” bass run in schools of like-sized fish, typically cruising edge cover, waiting for an unsuspecting morsel to swim into the open, where they inhale it. At that point of their young lives, those intermediate bass can’t navigate the dense cover. Advantage small fish, until they unwittingly emerge.
For bigger bass, expect them to be mostly solitary, preferably off points, next to a sunken log, or some other well defined structure, next to deep water. By then, their preference is to feed mostly by ambush.
But, we must always think about habitat for small fish, since they are the food chain for our bigger fish. Remember this—it takes about ten pounds of baitfish for a game fish to gain a pound. It also takes about ten pounds of food for baitfish to gain a pound, collectively. That food pyramid is why we pay attention to the detail of habitat.
Understanding that concept helps us with the next principle. This one is fun for discussion. I firmly believe that 90% of the fish live in 10% of a pond on any given day at any given moment. What that means to us, as lake designers, is to have some reasonable idea of what fish expect, so we can provide it. Here’s where it gets a little complicated. That 10% changes according to season, photoperiod, and time of day—all factors of which we have very little comprehension. Translation? Every lake needs about 20-30% of its area with some type of habitat or areas of fish attraction.
One big question bandied about in the fisheries world is how influential habitat is to a lake’s productivity. My response to that conundrum is that habitat is the most significant factor in a lake’s productivity and its destiny. You can have the most fertile water on the planet, with a comprehensive feeding program, but if you don’t have the best habitat for your target fish, and have it in the proper quantities, you can money-whip a lake until the cows come home and it won’t meet the highest of expectations.
Okay. We’ve got the concept and the philosophy.
What’s that got to do with Dr. Beck’s lake?
The next step is to map out the lake bottom and figure out the proposed water line. Set flags at the water line. As he does that, I suggested he also set flags at three feet deep, six feet deep, and if he’s totally into this lake design thing, nine feet. Make a map of the lake bottom, even if it’s hand drawn. First, study all the areas three feet deep and less. I think it’s totally okay to have some shallow water where aquatic plants can grow. Those areas become nursery areas. Just don’t let those zones cover more than 5-8% of the surface area. And, where those shallow areas exist, define them by giving them a border via cutting the dirt deeper, steeper, where he wants those grass beds to end. All the areas he doesn’t want to be shallow, he needs to move dirt to build peninsulas or underwater humps.
As he studies the map and spends time on site, I recommended he think about those shallow areas and how young fish will use them to hide in the dense vegetation. As he purposely designs those shallow areas, think about proximity to other pieces of the habitat puzzle. Shallow vegetated areas should be adjacent to spawning beds. Look for shallow areas where the earthmover can scrape off topsoil, add gravel, and give sunfish plenty of places to have their babies. Eggs hatch, and then babies want to head for cover. Predator fish love to linger near that cover, so going toward the main body of the lake, provide ridges in deeper water, next to those shallow areas. Those are the perfect places to enhance with big logs, tree canopies, artificial structure and the like. As he thinks through his design, he must figure out how to tie it all together with funnels, cuts, humps, and travel corridors.
Here’s where we’re going on this habitat journey. We want all the different elements in the best quantities. You want significant amounts of area for reproduction, for baby fish to hide, and for young fish to have safe areas. Provide for the babies by giving them safe zones and plenty of care, but be sure the door is open where they can get out and get eaten by the cruel, real world. After all, game fish will rule this underwater world.
For today, my best advice is this: Draw a map with close-to-accurate contour lines at 3, 6, and 9 feet of depth. Then, with colored pencils, crayons, pens, or media of choice, start drawing in what he’d like to build in the lake. Most habitat will be peripheral. A minor amount will be in deeper water.
Plot the spawning beds in shallow water, near other shallows where submerged aquatic plants can grow. Define those areas by designing a rapid drop into deeper water. Along those drops, think about underwater humps and channels next to natural, or manmade points along the shoreline.
As you think through this exercise, keep focused on creating an underwater community that inhabits about 20-30% of the lake bottom, with consideration to those varying seasons—meaning we’ll want congregation areas such as brush piles or artificial structure in deeper water for hot summer months and winter when fish prefer deeper water.
My last point is this—in the summer, many fish will choose places of thermal refuge in natural lakes. For us, that means they like to have some kind of structure or cover where they can be just above or inside the thermocline. Almost all unaerated lakes have a thermocline at half their depth. So, if this lake has lots of 14-foot water, the thermocline will typically sit at seven feet. Provide structure in the form of trees or artificial structure or humps that invade that depth, and make sure that habitat element is in proximity to the nearest shallow water habitat. If that can be done, you’ve provided a good home for fish, as well as targets for anglers to fish.
If you build the best habitat, in adequate amounts, the food chain will thrive and the fishery will be much easier to manage. As the fishery matures, the biggest issue will be catching and harvesting enough fish—and that’s a pretty good problem to have.
For a low maintenance lake, what happens during this key planning phase will directly impact the manageability of the lake in its years ahead.