Introduction: The Imperative for Climate-Resilient Water Quality Practices
Climate change is posing significant risks to water quality and the effectiveness of management practices designed to protect water resources. Changing precipitation patterns, increased temperatures, and other climatic shifts can directly impact the physical, chemical, and biological processes that underpin the performance of urban stormwater controls, agricultural conservation practices, and forestry best management practices (BMPs).
In the face of these emerging threats, communities must prioritize building resilient systems that can continue to achieve water quality goals despite the anticipated impacts of a changing climate. This requires a comprehensive assessment of the sensitivity and adaptability of different practices, as well as targeted strategies to modify or enhance practices to increase their climate resilience. By taking a proactive, forward-looking approach, water managers can protect vital water resources and ecosystems while also ensuring long-term return on investment in water quality infrastructure.
Understanding the Climate Change Threat to Water Quality Practices
Climate change is expected to have wide-ranging and cascading effects on water quality through shifts in precipitation, temperature, and other environmental conditions. Some of the key climate change impacts include:
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Increased Frequency and Intensity of Extreme Precipitation Events: More intense and frequent storms can reduce the capacity of stormwater control structures, wash out agricultural conservation practices, and damage forestry BMPs like stream buffers.
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Rising Temperatures: Warmer air and water temperatures can degrade biological and chemical processes that underpin the performance of many water quality practices, such as vegetation growth and pollutant removal rates.
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Shifting Precipitation Patterns: Changes in the timing, frequency, and form (rain vs. snow) of precipitation can alter the hydrology that drives the functioning of water quality practices, potentially reducing their effectiveness.
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Prolonged Drought: Droughts can negatively impact vegetation health and the ability of practices to infiltrate, filter, and treat runoff.
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Increased Wildfire Risk: More severe wildfires can damage forestry BMPs, reduce water quality, and increase sedimentation and other pollutant loads.
The specific impacts will vary across different regions and watershed settings, reflecting the complex interplay between climate, land use, and water management factors. But in general, climate change is expected to stress many conventional water quality practices, requiring communities to identify and implement more resilient approaches.
Assessing the Climate Resilience of Urban Stormwater BMPs
Urban stormwater infrastructure, including both gray (engineered) and green (natural) BMPs, face a range of climate change-related threats.
Gray Stormwater Infrastructure: Traditional stormwater detention basins, storm sewers, and other engineered structures are highly sensitive to changes in precipitation intensity and frequency. Increases in heavy rainfall events can exceed the design capacity of these systems, leading to reduced runoff capture and treatment. Without modifications to design standards and sizing, gray infrastructure will become increasingly ineffective at controlling urban pollutant loads.
Green Stormwater Infrastructure: Nature-based practices like bioretention cells, vegetated swales, and constructed wetlands rely on a combination of physical, biological, and ecological processes that can be disrupted by climate change. Increased storm intensity and runoff volumes may reduce contact time and treatment efficiency, while changes in temperature and precipitation can impact vegetation health and pollutant removal rates. At the same time, green infrastructure generally offers greater adaptability through modular, distributed designs that can be expanded over time.
Overall, urban stormwater systems that leverage both gray and green infrastructure approaches tend to exhibit higher resilience. The flexibility and co-benefits of green practices help offset the rigidity of engineered solutions. However, all urban BMPs will require evaluation and potential redesign to maintain performance under future climate conditions.
Enhancing the Climate Resilience of Agricultural Conservation Practices
Agricultural conservation practices are designed to holistically manage soil, water, and other natural resources to control pollutant runoff while supporting productive landscapes. Climate change poses threats to the effectiveness of many of these practices through changes in hydrology, temperature, and other environmental factors.
Practices Focused on Pollutant Source Control: Practices like conservation tillage, cover cropping, and nutrient management that work by reducing the mobilization and transport of pollutants from the landscape may become less effective as rainfall intensity and erosive forces increase. Shifts in growing seasons and plant productivity can also impact the performance of these source control practices.
Practices Focused on Pollutant Trapping and Treatment: Structural practices such as constructed wetlands, sediment basins, and vegetated buffers rely on physical, chemical, and biological processes to filter, settle, and transform pollutants. Increased flows and altered hydrology can reduce the contact time and treatment capacity of these practices.
Modeling studies suggest that some conservation practices, such as no-till and cover crops, may be able to maintain or even enhance their pollutant removal performance under future climate conditions by leveraging increased plant productivity. However, many practices are likely to see declines in effectiveness, necessitating adjustments in siting, design specifications, and integration within multifunctional practice systems.
Preserving the Water Quality Benefits of Forestry BMPs
Forested lands generally provide excellent water quality protection, but the BMPs used to manage these landscapes can be vulnerable to climate change impacts. Key concerns include:
Streamside Management Zones (SMZs): Riparian buffers along waterways play a critical role in shading streams, stabilizing banks, and filtering runoff. However, increased flood flows, erosion, and temperature can degrade the functionality of these SMZs over time.
Prescribed Fire and Fuel Management: Efforts to reduce wildfire risk through controlled burning and mechanical thinning are essential for maintaining healthy, fire-resilient forests. But the ability to implement these practices may be hindered by factors like increased drought, unpredictable weather, and the spread of invasive species.
Forest Regeneration: The success of reforestation and natural regrowth after disturbances like harvesting can be threatened by climate change-driven shifts in temperature, precipitation, and pest/disease pressures.
Forestry BMPs that rely on relatively fixed, engineered components (e.g., roads and culverts) or the establishment of mature vegetation over long timescales tend to have lower adaptability compared to more flexible, ecosystem-based practices. Integrating climate resilience principles into BMP design and implementation will be critical to sustaining the water quality benefits of healthy, functioning forests.
Prioritizing and Implementing Climate-Resilient Practices
Improving the climate resilience of water quality practices requires a multilayered approach that considers both the intrinsic properties of individual practices as well as their integration within broader management systems and landscapes.
At the practice level, key factors to assess include:
Sensitivity: The degree to which a practice’s performance is dependent on specific environmental conditions (e.g., precipitation, temperature) that are expected to change.
Adaptability: The ease with which a practice can be modified, expanded, or redesigned over time to maintain functionality under evolving climate conditions.
Practices exhibiting lower sensitivity and higher adaptability – such as modular green infrastructure or flexible agricultural conservation systems – should be prioritized for new installations and retrofits. Highly sensitive practices with limited adaptability may still have value but require more intensive monitoring, maintenance, and eventual replacement.
Beyond individual practices, a systems-level, risk-based approach is essential. This involves:
Conducting Vulnerability Assessments: Evaluating the cumulative impacts of climate change on water quality across a watershed or region, considering interactions between different land uses, infrastructure, and natural systems.
Implementing Adaptive Management: Employing flexible, iterative strategies that allow for ongoing adjustments to practice selection, design, and integration as climate conditions evolve.
Fostering Partnerships and Collaboration: Engaging diverse stakeholders – including downstream water users – to align management objectives, coordinate investments, and leverage multiple funding sources.
By prioritizing resilient practices and embedding climate adaptation within broader water quality management frameworks, communities can better protect valuable water resources in the face of a changing climate.
Conclusion: Charting a Course for Climate-Ready Water Quality
Transitioning to climate-resilient water quality systems is both an imperative and an opportunity. While the challenges posed by climate change are significant, strategic investments in resilient practices and adaptive management approaches can not only safeguard water quality, but also yield complementary benefits for community resilience, ecosystem health, and sustainable development.
By drawing on the lessons and best practices highlighted in this article, water managers and community leaders can chart a path forward that anticipates future climate impacts, leverages flexible and nature-based solutions, and engages diverse stakeholders in collaborative efforts to secure clean, reliable water resources for generations to come. Through this proactive, systems-oriented approach, we can build the climate-ready water quality systems required to support thriving, sustainable communities.
