Manage Rivers, Lakes, and Other Freshwater Ecosystems for Climate Change

Due to climate change, rising air temperatures are already warming freshwater ecosystems. Some lakes and streams have already experienced water loss due to summer droughts. These and other changes, are likely to continue and accelerate in the coming decades and impact water quality and quantity, presenting negative implications for freshwater ecosystems and the species that rely on these vulnerable habitats.

Climate Change Impacts: Current and Predicted

Freshwater systems include large lakes, ponds, rivers, wetlands, streams, and seasonal vernal pools. The response of these ecosystems to climate change impacts will vary based on current conditions, regional changes in temperature and precipitation, and more.

Observed and predicted climate change impacts to freshwater ecosystems include:

  • Earlier spring floods, and/or stronger and more frequent flooding. The overall amount of spring runoff may also decline, as winter snowpack volume decreases.
  • Greater risk of erosion and sedimentation.
  • Species — both plants and wildlife — shifting their ranges to previously cooler environments. Some coldwater species such as trout may lose a significant percentage of their current range.
  • More frequent and severe droughts may reduce water volume in some habitats, thus threatening vital wildlife habitat.
  • Greater risk of disease and insect pests, including the potential for these stressors to shift their ranges into regions where they previously could not survive.
  • Reductions in lake or river ice.

Warmer water, earlier snowmelt, and the increased severity and frequency of both floods and droughts will impact freshwater ecosystems across the United States.

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Recommendations for Adaptation

Despite management challenges, land trusts are well positioned to manage rivers, lakes and other freshwater habitats for the multiple benefits – both ecological and economic – they provide. As the Ecological Society of America relates in Sustaining Healthy Freshwater Ecosystems, there is growing recognition that functionally intact and biologically complex freshwater ecosystems provide many economically valuable commodities and services to society. These services include flood control, transportation, recreation, purification of human and industrial wastes, habitat for plants and animals, and production of fish and other foods and marketable goods. Over the long term, intact ecosystems are more likely to retain the adaptive capacity to sustain production of these goods and services in the face of future environmental disruptions such as climate change. These ecosystem benefits are costly and often impossible to replace when aquatic systems are degraded. For this reason, deliberations about water allocation should always include provisions for maintaining the integrity of freshwater ecosystems. Aquatic ecosystems can be protected or restored by recognizing the following:

  • Rivers, lakes, wetlands, and their connecting ground waters are literally the “sinks” into which landscapes drain. Far from being isolated bodies or conduits, freshwater ecosystems are tightly linked to the watersheds or catchments of which each is a part, and they are greatly influenced by human uses or modifications of land as well as water. The stream network itself is important to the continuum of river processes.
  • Dynamic patterns of flow that are maintained within the natural range of variation will promote the integrity and sustainability of freshwater aquatic systems.
  • Aquatic ecosystems additionally require that sediments and shorelines, heat and light properties, chemical and nutrient inputs, and plant and animal populations fluctuate within natural ranges, neither experiencing excessive swings beyond their natural ranges nor being held at constant levels.

New policy and management approaches will be required to protect aquatic ecosystems and their functions. The conservation community is already engaged in watershed protection to improve water quality, reduce flooding impacts, and enhance valuable habitat. For example, the Elkhorn Slough Foundation in California has targeted land acquisition and restoration projects to restore and reconnect floodplains to improve habitat and ecosystem health. In the Midwest the Southwest Michigan Land Conservancy (SWMLC) similarly focuses land management and acquisition efforts on maintaining and improving natural communities. SWMLC’s stewardship efforts include removing vegetation that is uncongenial to infiltration of rainwater, and restoring remnant lake plain prairie habitats for the multiple flood control, water quality, and habitat benefits these systems provide. Read more examples of land trust efforts to protect and improve water resources. Land trusts working to manage rivers, lakes and other freshwater habitats may wish to:

  • Assess vulnerability of habitat(s) to climate change impacts, such as earlier snow-melt, increased flood risk or dryer summers and changing water levels and water quality. Note: these impacts will vary by region and freshwater ecosystem consider scenario planning to optimize stewardship efforts;
  • Determine whether currently protected habitats are likely to shift their range northward, or to higher elevations. If so, consider the feasibility and value of extending the protected area’s boundaries to include this new territory in order to “conserve the stage” for species and ecosystems.
  • If species migration seems likely, look to remove barriers that may impede migration (dams, for example).
  • Increase the overall health and resilience of existing habitats by removing invasive plants, restoring native species, and protecting habitats from development and other stressors.
  • Wherever possible, protect the health of established ecosystem services, such as stream buffers, which may help protect a stream or river from increased erosion of nearby land.
  • Adopt an adaptive management policy to verify that your stewardship interventions are achieving your goals.
  • Support mitigation policies and actions to reduce the potential extent of future climate change today.

Learn More

Learn about potential climate change impacts, and identify variables that are relevant to your region or land-type.