Climate Impacts on Water Quality
The adaptation strategies provided below are intended to inform and assist communities in identifying potential alternatives. They are illustrative and are presented to help communities consider possible ways to address anticipated current and future climate threats to contaminated site management.
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- Climate Impacts
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Stormwater Runoff
Apply Green Infrastructure Strategies
- Use Bioretention to collect stormwater runoff
Bioretention is an adapted landscape feature that provides onsite storage and infiltration of collected stormwater runoff. Stormwater runoff is directed from surfaces to a shallow depression that allows runoff to pond prior to infiltration in an area that is planted with water-tolerant vegetation. As runoff accumulates, it will pond and slowly travel through a filter bed (pictured on the right) where it either infiltrates into the ground or is discharged via an underdrain. Small-scale bioretention areas are often referred to as rain gardens. - Use Blue Roof to hold precipitation after a storm event and discharge it at a controlled rate
A blue roof is designed to hold up to eight inches of precipitation on its surface or in engineered trays. It is comparable to a vegetated roof without soil or vegetation. After a storm event, precipitation is stored on the roof and discharged at a controlled rate. Blue roofs greatly decrease the peak discharge of runoff and also allow water to evaporate into the air prior to being discharged.20 Precipitation discharge is controlled on a blue roof through a flow restriction device around a roof drain. The water can either be slowly released to a storm sewer system or to another GI practice such as a cistern or bioretention area. - Use Permeable pavement to allow runoff to flow through and be temporarily stored prior to discharge
Permeable pavement includes both pavements and pavers with void space that allow runoff to flow through the pavement (pictured left). Once runoff flows through the pavement, it is temporarily stored in an underground stone base prior to infiltrating into the ground or discharging from an under drain. Permeable pavers are highly effective at removing heavy metals, oils, and grease in runoff. Permeable pavement also removes nutrients such as phosphorous and nitrogen. Soil and engineered media filter pollutants as the runoff infiltrates through the porous surface. The void spaces in permeable pavement surfaces and reservoir layers provide storage capacity for runoff. All permeable pavement systems reduce runoff peak volume. - Use Underground storage systems to detain runoff in underground receptacles
Underground storage systems vary greatly in design. Underground storage systems detain runoff in underground receptacles that slowly release runoff. Often the underground receptacles are culverts, engineered stormwater detention vaults, or perforated pipes. One of the benefits of underground storage is that it does not take up additional surface area and can be implemented beneath roadways, parking lots, or athletic fields. Underground storage systems are typically designed to store large volumes of runoff and therefore can have a significant impact in reducing flooding and peak discharges. - Use a stormwater tree trench to store and filter stormwater runoff
A stormwater tree trench is a row of trees that is connected by an underground infiltration structure. At the ground level, trees planted in a tree trench do not look different than any other planted tree. Underneath the sidewalk, the trees sit in a trench that is engineered with layers of gravel and soil that store and filter stormwater runoff. Stormwater tree trenches provide both water quality and runoff reduction benefits. - Use a retention pond to manage stormwater
A retention pond is one of the earliest prototypes of GI, and is now considered a more traditional type of stormwater infrastructure because it has been integrated into gray infrastructure design. It is an engineered stormwater basin designed to store runoff and release it at a controlled rate while maintaining a level of ponded water. Pollutants and sediment loads are reduced as the runoff is retained in the basin. Retention ponds are a very common stormwater management practice and may be designed with sustainable elements to increase water quality and decrease peak discharges. Vegetated forebays may be added to increase sediment removal as well as provide habitat. Another enhancement to traditional stormwater retention ponds is the addition of an iron enhanced sand filter bench that removes dissolved substances such as phosphorus from runoff. - Use extended detention wetlands to reduce flood risk and provide water quality and ecological benefits
Extended detention wetlands, such as the one shown in the figure on the right, may be designed as a flood mitigation strategy that also provides water quality and ecological benefits. Extended detention wetlands can require large land areas, but come with significant flood storage benefits. Extended detention wetlands can be created, restored (from previously filled wetlands), or enhanced existing wetlands. Wetlands typically store flood water during a storm and release it slowly, thereby reducing peak flows. An extended detention wetland allows water to remain in the wetland area for an extended period of time, which provides increased flood storage as well as water quality benefits.29 Extended detention wetlands are distinct from preservation of existing wetlands, but the two practices often are considered together as part of a watershed-based strategy.
Use Climate & Land Use Data
- Consider how current design standards are formulated a starting point to the discussion
Rather than starting a conversation with a discussion of climate change projections, understand the current design standard for stormwater management. Then, engage decision makers to seek agreement on a threshold (e.g., the community will prepare for X storm) that is informed by historic data and reflects the risk tolerance of the community (e.g., what level of damage or disruption the community can tolerate at different costs). This also entails understanding the current design standard and whether performance can be enhanced for projects in the region. - Demonstrate the use of dynamical downscaling on research projects at the site scale
Decision makers can use local resources for climate change data from researchers at organizations within the area, such as universities, state meteorological agencies, and other organizations that may be involved in downscaling of climate change scenarios. - Develop a "wish-list" of data that should be collected to improve understanding of climate changes
Stormwater managers and geographic information system (GIS) staff can begin to collect this needed local data (e.g., establish and maintain more local weather gauges and monitoring stations). Partners in the community or neighboring jurisdictions may also be interested in pooling resources to develop or improve data sets. - Use resources to show historical and future trend lines
To understand future climate changes, techniques that use historic data, such as analogue events or other sensitivity and threshold information in the historic record, can be used as illustrations (e.g., see the IPCC [Intergovernmental Panel on Climate Change] report Climate Change 2001: Working Group II: Impacts, Adaptation, and Vulnerability, Section 3.5. EPA's SWC and SWMM-CAT provide regional downscaled climate projections. EPA is also developing a web application for visualizing and downloading climate model output: the Global Change Explorer.
Use Natural Infrastructure
- Build swales and rain gardens
Water temperature benefits include getting water underground and maintains aquifers. Other benefits can included keeping stormwater runoff out of waterways. - Control stormwater runoff
Water temperature benefits include reducing high peak flows that contribute to erosion and channel changes. Other benefits can include restoring natural hydrology, returning to natural sediment transport and geomorphology, reestablishing natural disturbance, and raising water quality. - Plant trees
Water temperature benefits include shading the ground and keeping water temperature cooler. Other benefits can include controlling stormwater runoff and promoting infiltration. - Promote stormwater infiltration
Water temperature benefits include getting water into aquifers and away from exposure to sun, and recharging groundwater that supplies baseflow that regulates stream temperature. Other benefits can include restoring natural hydrology, returning to natural sediment transport and geomorphology, and reestablishing natural disturbance.
Erosion and Sedimentation
Apply Green Infrastructure Strategies
- Use Underground storage systems to detain runoff in underground receptacles
Underground storage systems vary greatly in design. Underground storage systems detain runoff in underground receptacles that slowly release runoff. Often the underground receptacles are culverts, engineered stormwater detention vaults, or perforated pipes. One of the benefits of underground storage is that it does not take up additional surface area and can be implemented beneath roadways, parking lots, or athletic fields. Underground storage systems are typically designed to store large volumes of runoff and therefore can have a significant impact in reducing flooding and peak discharges. - Use a retention pond to manage stormwater
A retention pond is one of the earliest prototypes of GI, and is now considered a more traditional type of stormwater infrastructure because it has been integrated into gray infrastructure design. It is an engineered stormwater basin designed to store runoff and release it at a controlled rate while maintaining a level of ponded water. Pollutants and sediment loads are reduced as the runoff is retained in the basin. Retention ponds are a very common stormwater management practice and may be designed with sustainable elements to increase water quality and decrease peak discharges. Vegetated forebays may be added to increase sediment removal as well as provide habitat. Another enhancement to traditional stormwater retention ponds is the addition of an iron enhanced sand filter bench that removes dissolved substances such as phosphorus from runoff.
Consider Cost and Benefits of Green Infrastructure
- Consider long-term benefits of green infrastructure in economic analysis of stormwater management plans
Train local appraisers/commissioners to capture the full value of green infrastructure. Incorporate cobenefits into ROI calculations, such as ecosystem services and quality of life factors.
Use Natural Infrastructure
- Control soil erosion in the watershed
Water temperature benefits include keeping sediment from clogging streambeds and interfering with groundwater exchange and keeping heat-trapping particles out of waterways. Other benefits can include returning to natural sediment transport and geomorphology, and raising water quality. - Control stream bank erosion
Water temperature benefits include keeping stream channels from getting wider and shallower and warming more easily. Other benefits can include maintaining natural sediment transport and geomorphology, and raising water quality.
Harmful Algal Blooms
- Develop models to understand potential water quality changes
In many areas, increased water temperatures will cause eutrophication and excess algal growth, which will reduce drinking water quality. The quality of drinking water sources may also be compromised by increased sediment or nutrient inputs due to extreme storm events. These impacts may be addressed with targeted watershed management plans. - Manage reservoir water quality
Changes in precipitation and runoff timing, coupled with higher temperatures due to climate change, may lead to diminished reservoir water quality. Reservoir water quality can be maintained or improved by a combination of watershed management, to reduce pollutant runoff and promote groundwater recharge and reservoir management methods, such as lake aeration. - Install effluent cooling systems
Higher surface temperatures may contribute to making water quality standards or make temperature criteria more difficult to attain, as well as lead to greater outbreaks of harmful algal blooms. Therefore, efforts to reduce the temperature of treated wastewater discharges, such as additional effluent cooling systems, may be needed to help maintain water quality. - Visit the Water Utility Source Water Quality Page - to view more Adaptation Strategies that can help support efforts to reduce water quality impacts from harmful algal blooms.
Source Documents
These strategies are adapted from existing EPA, CDC and other federal resources. Please view these strategies in the context provided by the primary source documents:
- Being Prepared for Climate Change: A Workbook for Developing Risk-Based Adaptation Plans, Actions That Could Reduce Water Temperature, Appendix F
- Green Infrastructure for Climate Adaptation Stormwater
- Stormwater Management in Response to Climate Change
Disclaimer
The adaptation strategies provided are intended to inform and assist communities in identifying potential alternatives. They are illustrative and are presented to help communities consider possible ways to address anticipated current and future climate threats to contaminated site management. Read the full disclaimer.