The construction phase is complete, the last truck has rolled away, and the basin is ready. But your project is destined for so much more than the pretty picture it presents today. A healthy impoundment is a remarkably complex organism with multiple external inputs from a much larger biome, and it needs constant, skilled, hands-on attention to keep it running at peak health. Your job will focus on actively managing internal inputs, such as water levels and the food sources you cultivate, to align with seasonal rhythms and the needs of migrating waterfowl.
The guiding philosophy behind this approach is Moist-Soil Management (MSM). It’s a way of thinking about habitat that says, “Instead of fighting nature by planting agricultural crops, let’s work with natural wetland ecology. Let’s mimic the natural wet/dry cycles of a river floodplain to unlock the immense potential of the native seed bank that’s already in the soil.”
MSM is widely recognized as the gold standard for producing vast quantities of high-value, natural waterfowl foods. Instead of planting a single basic crop like corn, MSM mimics the natural wet-and-dry cycles of a river floodplain to stimulate the germination of native, seed-bearing plants like smartweeds and millets. We’ll get into the specific techniques in the next section. For now, the key takeaway is that MSM isn’t a single task; it’s a year-round commitment that follows seasonal cycles.
Let’s start by walking through the calendar, covering those critical tasks—and the techniques they require—that demand your attention. In this chapter, we’ll tackle the growing season (otherwise known as Spring and Summer).
Spring: The Great Awakening
Not to put too much pressure on, but spring is when you set the table for the fall. More than any other season, the actions you take in the spring will determine the quality and quantity of the food your impoundment produces. Your entire goal during this period is to precisely manage the water to awaken the dormant seed bank in your soil.
The Essential Slow Drawdown
Your success as a Moist-Soil Management practitioner hinges on mastering the slow drawdown. The idea is to precisely mimic a natural, receding floodplain as it gradually exposes moist soil to air and sunlight, triggering the germination of desirable native plants.
When to Start
Timing is everything. You’ll typically begin your drawdown in late spring, after the threat of a hard frost has passed but while there’s still plenty of growing season ahead.
The Pace is Key
“Slow” is the operative word. You’re not just pulling the plug in a washbasin. A good rule of thumb is to drop the water level by just a few inches per week. You do this by removing one flash board at a time from your water control structure every 7-10 days.
The Result
This gradual recession creates a “feathered edge” of newly exposed mudflats that follows the water down the gentle slopes of your feeding benches. Within a couple of weeks, you should see a lovely fine, green carpet of new seedlings—smartweed, millet, sedges—sprouting in the wake of the receding water.
The Optional Reset: Soil Disturbance
If your impoundment is healthy and productive, a slow drawdown is all you’ll need. However, if you notice undesirable perennial plants (like cattails or rushes) starting to dominate, you may need to hit the reset button. After a complete drawdown, once the soil is dry enough to support a tractor, a light discing or tilling of the impoundment floor is a powerful tool for breaking up the root systems of those unwanted perennials and stimulating a new flush of germination from the seed bank.
Now, this isn't an annual chore. Think of discing as a strategic reset you perform only every 3 to 5 years. It’s the same idea as defragging an old hard drive: you’re not wiping your valuable data; you’re just cleaning up the clutter and reorganizing the system to keep it running fast and clean.
Summer: The Growing Season
If spring is about setting up the table, summer is about patient vigilance as the pot gently simmers. Your primary focus during the long, lazy days of summer is monitoring the plant growth you’ve stimulated, managing any undesirable species, and keeping your equipment and structures in good working order.
Scouting and Pest Control
Yes, you’re managing a waterfowl impoundment, not a military compound. But it’s still worthwhile to think of yourself as a soldier on foot patrol. At least once a week, you should be out in your dry impoundment, inspecting the health of your valuable moist-soil plants. Are they growing well? Is there any sign of insect damage or disease?
Don’t forget to scout for invading plants either! Maintaining a secure impoundment during the growing season requires a consistent holding strategy. While the periodic discing we covered in the “Spring” section is your best tool for a broad reset, you’ll still need to fight quick, small-scale skirmishes every summer since aggressive perennials like cattails or woody saplings like willows will always try to sneak in and establish a foothold.
Quick hint: Don’t let them. Once the growing season is in full swing and the impoundment is still dry, a carefully targeted, professional response is your best strategy.
Note from the Trenches: The Herbicide Minefield
When you see a patch of cattails starting to take over, it’s tempting to run to the nearest farm supply store and grab a jug of weed killer. Don’t do it. Most common herbicides are designed for dry land and contain additives called surfactants that are highly toxic to fish, frogs, and the invertebrates that are the base of your pond’s food chain.
For this job, you need a specific, aquatically-approved product. The two most common tools in a manager’s shed are aquatic-safe glyphosate (like Rodeo® or AquaNeat®) for general-purpose use, and imazapyr (like Habitat®) for the really tough-to-kill stuff like phragmites.
But here’s the most critical part, and it’s not up for debate: in most states, you can’t legally buy or apply these herbicides without a state-issued Pesticide Applicator’s License. The label on the bottle is a federal legal document, and the rules are strict. Even if you’re in a more permissive state, your best bet is always to hire a licensed professional or, at the very least, consult your local extension agent. Messing this up can kill your pond and could even land you in a world of legal trouble.
Maintenance and Mowing
The summer drawdown is the only time of year when your entire impoundment is dry and accessible. While you’re monitoring the plants, they’re pretty much doing their thing, so this is your singular window for some key maintenance activities.
Structure Check
There’s no better time to inspect your water control structure. Make sure your flash boards are in good shape and haven’t warped. If you have a screw gate, check the seals and grease any moving parts.
Berm Maintenance
Start by mowing the berms to prevent woody vegetation from growing, as their deep roots can compromise the dam’s integrity. As a bonus, a good mow makes it easier to spot any potential problems, like signs of erosion or animal burrows from muskrats or beavers—those need immediate corrective action.
