Water Resources

Water resources refer to sources of water that are useful or potentially useful for humans, as well as hydrologically-dependent ecological systems.

Water resources is a term that includes springs, seeps, rivers, lakes, oceans, and underground aquifers. Climate change is impacting water resources in a variety of ways. In many coastal areas freshwater aquifers may become infiltrated with salt water due to rising sea levels and inundation caused by storms and flooding. Changes in precipitation also impact water availability and water quality. Increases in precipitation can cause flooding, which often is associated with sedimentation and negative impacts from stormwater overflows. On the other hand, decreases in precipitation and snowpacks can deplete the availability of water supplies.

The impacts of climate change are will exacerbate many existing water quality and quantity problems.  For example in drier parts of the country, climate change is likely to increase water demand, diminishing already strained water supplies. Addressing the additional stress of climate change may require new approaches to managing land, water, waste, and ecosystems. As conservation experts and long-term resource stewards, the land trust community is uniquely poised to inform land and water management dialogs.

The United States’ Climate Science Program highlights the following trends:

• Most of the United States has experienced increases in precipitation and streamflow and decreases in drought during the second half of the 20^th century.
• There is a trend toward reduced mountain snowpack and earlier spring snowmelt run-off peaks across much of the United States. Where shifts to earlier snowmelt peaks and reduced summer and fall low flows have already been detected, continuing shifts in this direction are very likely and may have substantial impacts on the performance of reservoir systems.
• Water quality is sensitive to both increased water temperatures and changes in patterns of precipitation, and stream temperatures are likely to increase as the climate warms, causing direct and indirect effects to aquatic ecosystems. Changes in temperatures will most likely be evident during low flow periods, when they may pose greatest concern to aquatic systems.

IPCC climate simulations suggest that the United States may experience increased runoff in eastern regions, gradually transitioning to little change in the Missouri and lower Mississippi, to substantial decreases in annual runoff in the interior of the west (Colorado and the Great Basin). Runoff changes along the West Coast are projected to be negative, causing increased drying, but these decreases may be less substantial than those of the interior. Models suggest increased runoff in Alaska. These modeled changes are roughly consistent with observed trends in the second half of the 20^th century, which show increased streamflows over most of the United States with sporadic decreases in the West. Learn more about climate change impacts on water quality and quantity. 

Planners and Conservationists across many sectors are confronting the challenge of a changing water resource systems and impacts to water quality and supply. They will likely adopt a variety of adaptation practices, designed to better conserve water supplies, improve water recycling, and develop alternative strategies for water management.

Best Management Practices: What Land Trusts Are Doing

The land trust community is responding to water resource management challenges associated with climate change in various ways. For example, across the Western U.S., the Western Rivers Alliance has been working with local stakeholders to identify and protect vulnerable fish-bearing streams from changing temperatures by enhancing tree cover. In California the Elkhorn Slough Foundation is working to “reclaim floodplains” to protect communities, restore habitat functions, and enhance biodiversity. In the Great Lakes, the Southwest Michigan Land Conservancy’s Conservation Master Plan included an in-depth hydrological study aiming to address climate change impacts and support resiliency in this region’s diverse landscape, which ranges from forests and fields to streams, ponds, bluffs, and beaches. Scenic Hudson in New York has worked with partners to map and project sea level rise impacts in the Hudson River Valley, enabling them to help communities visualize and plan for changing inundation patterns. Similarly, in Florida, the North Florida Land Trust has mapped areas that will be inundated by sea level rise and is using this map to inform strategic conservation objectives. In Hawaii, the Hawaiian Islands Land Trust has implemented coastal conservation projects to promote habitat restoration, mitigate sea level rise, and enhance community sustainability by supporting localized food production. Read more case studies about water resources.

While there is no one-size-fits-all approach to address climate impacts, more and more, conservation organizations are working with their communities to identify opportunities to reduce vulnerabilities and build resilience to prepare for changing temperatures. Agencies are making similar strides to implement projects that reduce risks and plan for resilience by incorporating adaptation, mitigation, and engagement into their strategic goals and objectives.

Learn More

• Climate Change in Coastal Communities, EPA
• Ecological Impacts of Climate Change, NRDC
• Effects of Climate Change on Agriculture, Land Resources, Water Resources, and Biodiversity, U.S. Climate Change Science Program
• Preliminary Review of Adaptation Options for Climate-Sensitive Ecosystems and Resources, U.S. Climate Change Science Program
• Water: Celebrating Wetlands, NRCS