Advancing freshwater restoration

My Projects

• Key project facts

  Not involved with single projects – my role currently is trying to review the cumulative effects of multiple projects and understand the successes and failures of these. 

  I've found Denmark to be at the forefront of wetland restoration. Although I moved here after 1987, that’s when the first national water environment management plan was introduced—mainly to address pollution from intensive agriculture, especially nitrogen runoff affecting our freshwater and coastal systems. One of the early solutions was to create functional wetlands that could filter out these nutrients. This approach has been highly successful and laid the foundation for future efforts.

  Alongside this, I’ve worked near Erik Jeppesen’s group, which pioneered lake restoration techniques—particularly targeting eutrophic lakes that had shifted to turbid states. They experimented with methods like fish population management and sediment precipitation to return these lakes to clear, macrophyte-rich conditions.

  Over time, I became involved in evaluating these efforts. Denmark now has over 100 artificial lakes, created not by restoring old ones but by transforming low-lying agricultural land. Although their primary function was nutrient capture, many have turned out to be surprisingly rich in biodiversity. We're now studying how to better design such systems to maximize both ecological function and biodiversity from the start.

  A key lesson from large-scale projects, like the restoration at Skjern River Valley, is the importance of early stakeholder involvement. That restoration reversed decades of intensive drainage and monoculture but could have been far more beneficial to biodiversity—especially wading birds—if ecological planning had been integrated earlier. Much of my current work focuses on learning from these past efforts to improve future planning, both for ecological outcomes and societal engagement.

• What impact did these projects have on biodiversity, if any?

  Improve the overall quality of freshwaters to be suitable for biodiversity. In Denmark, over 100 artificial lakes, initially created to retain agricultural runoff, were later found to be surprisingly rich in species, particularly birds. Projects like the Skjern River restoration significantly increased breeding, staging, and wintering bird populations. The restoration of turbid lakes improved aquatic habitats, promoting the return of macrophytes and associated fauna.

• What work challenges did you face and what approach did you take to solve them?

  We identified several key challenges in restoration work. A major issue was nutrient pollution from intensive agriculture, which was addressed by creating functional wetlands to filter runoff—later found to be rich in biodiversity. Another challenge was restoring eutrophic, turbid lakes, solved through techniques like fish management and sediment removal. Early projects often lacked biodiversity goals and stakeholder input, leading to missed opportunities. These experiences highlighted the need for multi-functional wetland design and early, inclusive engagement with stakeholders to ensure ecological and social success.

• What lessons learned are transferable to other places/projects?
  
  1. Functional wetlands can deliver unexpected biodiversity gains even if initially designed for nutrient removal—underscoring the value of multi-purpose design in restoration projects.
  2. Lake restoration techniques, such as fish community management and sediment control, are effective in shifting eutrophic systems back to clear-water states and can be adapted elsewhere.
  3. Early and inclusive stakeholder engagement is crucial to minimize conflicts and ensure long-term support and multifunctional use of restored areas.
  4. Retrospective evaluations are essential to improve future planning—learning from past successes and shortcomings enhances ecological and societal outcomes.
  5. Restoration must integrate ecological, hydrological, and social objectives from the outset to maximize ecosystem services.