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Functional Wetland Design: Why It Matters and 7 Tips for Wetland Construction Success

Photo of Rutgers wetland students learning out in the field.

The Wonders of Wetlands

Wetlands are essential components of our natural environment.  Providing shoreline protection, nursery for multiple freshwater and saltwater fishes, critical habitat for countless species of wildlife, storm water storage, nutrient filtration, sediment retention, niches that harbor unique species, shoreline protection and many other more subtle yet essential natural functions.  Legions of biologists, ecologists, and other scientists have studied and cataloged these diverse systems for decades.  

As the need to stem losses of these resources became more acute during the 1970’s and 1980’s, scientists endeavored to find ways in which degraded systems could be restored and new wetlands might be created.  These efforts led to some successful projects... and many not so successful projects. A few experts began to recognize that the failed sites typically had not adequately addressed replacement of hydrologic functions.

Mal Gilbert: Evolution of a Wetland Restorer
Photo of wetland instructor, Mal Gilbert
While an employee of the USDA Soil Conservation Service from 1976 through 1990, Mal Gilbert became increasingly interested in restoration of wetland systems. He began to apply many of the principles he learned as a USDA Soil Scientist and Soil Conservationist to “wildlife habitat improvement” projects on landowners’ conservation plans, and he carried these techniques into the private sector as an environmental consultant. 

Working with scientist and former Rutgers instructor, Dr. Gary Pierce, and others interested in wetland restoration, Mal began to realize that all natural wetland systems have very distinct patterns of wetness during the course of typical years.  In essence, he recognized that each wetland type has a “hydrologic signature” which can be determined by calculating the depth, duration and timing (DDT) of the water entering and leaving the wetland.  Furthermore, Gilbert realized that successfully constructing a new wetland relied on identifying a reference wetland’s hydrologic signature and re-creating that signature (and, thereby, its functions) on the new site.

DDT: The Critical Driver of Any WetlandGraph representing the importance of DDT vs other factors in a wetland restoration effort

Through discussions with Pierce, Mal realized that he was not alone in his observations.  Pierce and Gilbert agreed that perhaps the most important feature that drives any wetland system is the DDT.  
They recognized the importance of the landscape position of the wetland, the soil parent materials, climate, and, of course, the types of organisms in the wetland as critical factors as well, but realized that the distribution of water was at the heart of understanding the functions a particular wetland would be capable of performing. 

A Wetland Restoration and Construction Training Program is Born

Dr. Pierce and Mal started teaching a suite of courses on wetland restoration and creation principles in 1988 for a number of venues including the Rutgers Office of Continuing Professional Education, the US Army Corps of Engineers, and others.   

Their course emphasized their belief that you can’t successfully restore a wetland system or build a new functioning wetland without understanding and addressing wetland functional design. Functional hydrologic design focuses on identifying the functions of your reference wetland site and successfully transferring those functions to the newly constructed or restored site.

They were the first to teach these topics with a functional design approach.  

In 1993, Pierce published “Planning Hydrology for Constructed Wetlands” and he and Mal began using that publication as a centerpiece of their training courses.  In 1999, Pierce and Gilbert began a rewrite of the 1993 effort and had a draft manuscript nearly complete at the time of Dr. Pierce’s passing in 2011. Mal has continued to teach wetland construction courses for Rutgers on his own since.

Functional Exchange: The Future of Wetland Mitigation Standards

Regulatory agencies have revised their wetland mitigation standards away from an acre-for-acre replacement approach to a focus on replacement of quantifiable wetland functions.  Thus the approach that Pierce and Gilbert developed both individually and then jointly in the late 1980’s has garnered growing support. 

Timeline showing changes in wetland restoration standards

For example, the State of New Jersey has incorporated many of the principles espoused by Pierce and Gilbert in New Jersey’s protocols for planning and development of wetland mitigation, creation and restoration projects.

More recently, the Ohio Environmental Protection Agency (OPEA) has expressed interest in learning more about the protocols and approach that have been taught at Rutgers for more than twenty years.  In fact, Mal has agreed to share information on successes and failures and to work with OEPA scientists as they develop their own set of standards and recommended procedures for wetland construction and restoration.

The first school to provide training opportunities in Gilbert & Pierce’s functional wetland design approach to construction and restoration, Rutgers is still one of only two universities where environmental professionals can learn this pioneering approach to wetland restoration.

Learn more about wetland construction through Rutgers’ hands-on Principles and Techniques class and our Planning and Functional Design course.

Mal Gilbert's 7 Fundamental Steps for Wetland Construction Success

By following a functional design approach and these seven steps BEFORE you begin constructing a wetland, you will greatly improve the probability of your wetland construction project’s success.

1) Define the project and goals in terms of wetland functions

2) Define the hydrogeomorphic setting and model the wetland hydrologic regime

3) Prepare a quantitative, predictive description of the hydrologic regime and use it to prepare the site’s physical design

4) Develop a substrate and subgrade management plan                                

5) Prepare a planting plan

(And once your project is underway....)

6) Oversee the construction and planting

7) Monitor with intent (follow-up is critical!)

Training Opportunities

Mal Gilbert just taught a wetland construction course at Rutgers in June and will be back on September 16 & 17 to teach his hands-on Wetland Construction: Planning & Functional Design class.

Learn more or register for this program at:

Other upcoming courses include:

Vegetation Identification for Wetland Delineation (Southern NJ) – September 23-24, 2013

Methodology for Wetland Delineation – October 16-19, 2013

Introduction to Wetland Identification – October 17, 2013

Vegetation Identification for Wetland Delineation (Winter) -- January 27-28, 2014

Photo of Rutgers wetland students doing field work

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