Engineered Ecosystem Revitalization via Treatment Train: A Cyborg Approach to Shoreline Wetland Restoration

There is no magic bullet when seeking solutions for environmental degradation. Unique and tailored technologies are required to meet the specific needs and address the individual circumstances and challenges of any one ecosystem or waterbody. What works for one system will unlikely succeed elsewhere without customization. More and more, scientists are realizing that innovative hybrid combinations of tried and true methods can make significant impacts, where more simplistic solutions have failed in the past.

Grand-Lake-St-Marys-Algae-Courtesy of Lake Improvement AssociationOne example of such an ecosystem is Grand Lake St. Marys, a 21-square mile lake in Auglaize and Mercer Counties, Ohio. The lake plays a major role in the local and regional economies but has recently been in crisis due to water quality impairments related to development surrounding the lake and from the agricultural boom in its watershed. Radical swings in water clarity and temperature fuel massive algal blooms that create a cascade of impacts, disrupting biological, chemical, and societal services provided by the lake. The lake has suffered from periods of dangerous levels of algal microcystin toxin, and in 2010, the lake was closed for an extended period as a result. While the problem facing the lake was clear, there was no easy solution due to the size, complexity, and severity of the lake’s ecosystem, not to mention the dependence of the local economy on the lake and its watershed. Based on all of these factors, the lake’s stakeholders developed a “cyborg” approach, one using a symbiotic relationship between engineered and natural systems to enhance targeted ecosystem processes to improve the health of the lake.

Ecosystems can fluctuate wildly as they seek to attain equilibrium under changing physical, climatic, biological and human inputs. These swings in the ecosystem can be seen through declines in ecosystem services, which were already evident in Grand Lake St. Marys’ toxic algal blooms. Re-establishing the equilibrium within the lake’s ecosystem to restore its services was the main goal.

Prairie Creek Treatment Train: Success of An Engineered Ecosystem

Prairie-Creek-Treatment-Train-Wetland-Berm-and-EmbaymentA pilot cyborg restoration approach was applied to the Prairie Creek drainage entering the lake. A treatment train system was developed to remove nutrients via a series of linked engineered, bio-technical, and natural treatment systems. Incoming water is captured upstream of the lake and pumped through the system at the rate of several million gallons per day, as the water is treated first with alum injection to capture excess nutrients, released into constructed wetlands, and then finally into restored shoreline wetlands, all before reaching the lake. The improvement in water quality provides the conditions needed for natural regeneration of wetlands beyond the influence of the engineered systems.

The system went into action starting during the summer of 2012. Natural re-establishment of shoreline vegetation in the embayment and constructed wetland system provides direct evidence of the effectiveness of this approach. Since that time, water quality monitoring of the system documented an average removal efficiency of 31% and 71% for nitrogen and phosphorus respectively, resulting in a complete shift in water quality and trophic state in the embayment and resurgence of naturally generating aquatic vegetation.