Building and Managing Wetland Ecosystems

Our Experience   

There are many good designs and the best depends on your project. Other than sharing our experience, we cannot make more specific recommendations because every job is different.

Flashboard Riser Structures are the most economical option. They work well for habitats and shallow ponds with sustained inflows or where the drainage area produces large flows.  Flashboard structures are less attractive in deeper ponds because it is not possible to completely backfill to the top of the structure.

Choose Inline Structures for deeper ponds and lakes. Inline structures are more stable, they are resistant to debris and can be accessed without entering the water.

6-Inch aluminum inline structures are our best-selling product. They are economical and can move plenty of water for most small habitats. Nothing is indestructible but our 6-inch aluminum structures will take a beating with no damage. We prefer to use 6-inch SDR35 pipe wherever practical.

We prefer plastic pipe because it does not corrode or promote galvanic corrosion of the drain structure.  We have dug out lots of heavy galvanized steel pipe that has been completely eaten away by corrosion. 

Access We learned early on to build a nice roadway around our projects for easy access with equipment and recreational activities. Our roadways are made from compacted soil and graded to shed water. We place them immediately adjacent to the water, on top of the pond berm or along the edges to provide access around the entire surface. We mow the roadways to encourage grass growth and minimize rutting and erosion.

Waterfowl Habits  

Small wetland habitats with grassy and woodland boundaries attract a wide variety of wildlife.  In addition to aquatic life and waterfowl, we have observed many animals.

Habitats are most productive when properly managed to encourage an early succession ecosystem.   This basically means an area that has natural grasses that grow in seasonally flooded conditions.   These ecosystems produce abundant seeds and support a thriving population of aquatic insects that are the main source of food for waterfowl. 

This habitat was flooded through the winter and drained in mid-May. Now in late June, the plants have recovered and are growing rapidly.

The area was barren four years ago when it was planted with Japanese Millet. The millet gave way to natural grasses and sedges.

The area is managed with a 6-inch in-line control box.

Seasonal Flooding

Successful Management requires that the water levels be drawn down at appropriate times to eliminate standing water while maintaining moist soil conditions then reflooding the areas at the appropriate times to maintain the ecosystem.    In practice, we allow our habitats to progress through various stages, allowing some woody vegetation to emerge before we intervene because we found that cover is also an important factor.  

Seasonal Drawdown

If the ecosystem is flooded for too long, too deeply, or kept dry for too long, undesirable plants will grow and the ecosystem will be less productive.   In the extreme example, it will turn into a swamp which is basically a shallow lake with trees. 

Include a Pond  

We enjoy fishing and usually include a pond to maintain aquatic life when the water levels are lowered.   Sometimes this is just a deep hole near the drain end.  Sometimes we create the habitat portion as a wide shallow ledge surrounding a pond in the center.   Fish benefit greatly from the shallow habitat areas in the transition months. 

This habitat is twelve years old. Trees and bushes are taking over and it is becoming less productive.

Later in the summer, after the baby geese and deer are grown, the trees will be cut and the area replanted with grasses.

This pond is an example of a pond surrounded by a habitat area. It is managed with a 6-inch in-line control box.

Use 6-inch PVC Pipe wherever practical

A six-inch pipe can move plenty of water for smaller habitats and pond leveling applications.  Pipe and fittings are readily available. 

We initially used large-diameter corrugated drainpipes on all drains.   Larger pipe is overkill for habitats under a few acres in size unless there is significant flow coming into the habitat.

There is no need to quickly flood or empty a habitat.   We found it is better to raise and lower water levels slowly.  A properly sloped six-inch pipe will move about 11 acre-inches of water in 24 hours.   Yes, it will take a few days to drain two feet of water off of a three-acre plot.  Yes, large rains will overwhelm the drain and might temporarily flood the area.   The slower pace and occasional flooding is beneficial for managed habitats.   Temporarily impounding runoff is good for downstream water quality.

We favor SDR 35 (green sewer pipe). It is durable, readily available and affordable enough for long runs like directing water hundreds of feet between habitats.

We have occasionally used solid core Schedule 40. It is tough, versatile and the cost difference is negligible compared to the total project cost for small runs. Schedule 40 is a more durable choice and it will accept a wide selection of standard fittings if other connections are desired.  Schedule 40 is more expensive and the couplings and gluing add additional cost and time. Even considering the high price differential, solid core Schedule 40 PVC may be a viable consideration in landscaped environments or in areas with vehicle traffic because the cost difference may be small compared to overall job cost and especially to the time to revisit the job, retrench and repair landscaping to fix a failure. 

Avoid foam core DWV (Drain Waste Vent) pipe because it is fragile.

Avoid 4-inch pipe because it clogs too easily.

This pond is drained with a 6” PVC pipe. The mud on the plants demonstrate it was completely flooded from a storm the previous day.

The entire area successfully drained overnight.

Flashboard Riser Structures are the most economical option

Flashboards work well for habitats and shallow ponds with sustained inflows or where the drainage area produces large flows.  Flashboard structures are less attractive in deeper ponds because it is not possible to completely backfill to the top of the structure.

Choose In-line Structures for deeper ponds and lakes

Inline structures are more stable, they are resistant to debris and can be accessed without entering the water.

Dealing with Flood Water  

There will always be the possibility of storm water over-running the drain. Or, the drain could plug up even if it is adequately sized. A good design must plan for these contingencies. Our grass-covered roadways easily withstand occasional floodwater overflows.

In areas where overflows can be excessive or frequent, we create spillways which are shallow channels across the roadway packed with riprap and topped with 1 ½ gravel and some soil. Grass will grow though this and it becomes very resistant to erosion. These are dry most of the time. Flood water will flow harmlessly across the spillway until the drain can catch up with the flow.

Always consider contingency plans for storm flows. We have worked on lakes with very large outlet drains that occasionally over-run the pipe and into the emergency spillway. We have also worked with tranquil ponds that collect water from large drainages. These ponds normally have no outflow but can become torrential rivers in a storm. We had an experience in the Sonoran desert where a tiny trickle of water in a wash would occasionally swell into a six-foot-deep, 120-foot- wide raging river during monsoon season. In that case, the wash was draining 25,000 acres of normally bone-dry desert. The back side of our 80-foot-long, 20-foot-wide, 4-foot-thick concrete overflow pad was  undermined after a particularly bad storm. The point being there will always be a bigger storm -- you will never have a large enough pipe!

Consider What Is Downstream  

Your design must consider the potential consequences of damage to downstream property, structures, roads, etc. should a breach occur. 

We once repaired a large lake built many years ago.  We opened the drain gate and thought little of it until we realized we had flooded the road a mile downstream.  Fortunately it is in a rural setting and there was no damage but we learned a valuable lesson.  We limit our projects to relatively flat ground where the potential from a dam, dike or berm breach is insignificant.  We do not worry about a breach because our downstream areas are grassy meadows, wetland habitats or wooded areas capable of safely receiving the entire contents of the pond if the berm were to breach.

Just a trickle… most of the time!

Placement   We place our water level control boxes beside our roadways for easy access with equipment. We widen the area in the roadway near the outlet to accommodate the water control box where it is out of the traffic path.

Two or More Water Level Control Boxes are useful to split water flow between multiple habitats or seasonally flood habitats from a common ditch or pond.   The stop logs can be adjusted to stop flow to the pipes feeding the habitats and divert all flow to the drains when we want to dry the habitats. The stop logs can be readjusted to divert water flow to the habitats and stop the drain when we want to flood the habitats.

Common Search Terms Associated With Our Products:

Water Level Control

Inline Water Level Controller

Inline Water Level Control Structure

Pond Leveler

Water Gate

Pond Drain

Lake Drain

Water Impoundment Drain

Retention Pond Drain

Flashboard Riser

Flashboard Drain

Flashboard Inlet Structure

Drop Board Riser