Targeted Adaptation Strategies for Climate Impacts on Water Quality

Targeted Adaptation Strategies for 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 current and future climate threats to water quality.

 

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Use Climate and Land Use Data

There will likely never be a tool to predict storm events with precision. Communities will need to develop new ways of thinking and planning, such as analyzing decisions by their robustness over a range of potential changes, employing risk management techniques, using principles that maximize minimum losses or minimize maximum losses and other approaches for decision making under uncertainty.

They are often sufficient to support a near-term conversation about how stormwater management may need to change to accommodate changes in climate.

Land use has a tremendous effect on climate change impacts on stormwater management; managers can incorporate land use change maps into planning discussions. USEPA's Integrated Climate and Land Use Scenarios (ICLUS) project can serve as a resource. Consider updates to data management practices to facilitate use of the best and most recent data.

If better understood, it may motivate local planners to consider climate change when making infrastructure decisions.

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.

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.

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.

These scenarios (complete with uncertainty bounds) can be used by communities across a region, minimizing the need for individual communities to spend limited resources to determine which climate model results are appropriate to their planning needs (see SFWMD, 2011 for example of regional climate and sea level rise scenarios produced for south Florida counties and municipalities by the South Florida Water Management District).

Via training, new hires or sharing of staff across the county or a group of municipalities.

Local decision makers are often working with old data. Simply updating storm standards to match current precipitation patterns can result in a marked improvement. Accurate historical climate information can help serve as a bridge to discussions regarding future climate projections (which are less certain and may be less readily received by skeptical planners and decision makers).

Re-evaluating accuracy of land use maps, especially in areas experiencing rapid development, can ensure the best available data about the extent and location of impervious surfaces is used.

For example, the U.S. Army Corps of Engineers has been helping communities better understand hydrologic modeling (U.S. ACE, 2015) and Federal Emergency Management Agency (FEMA) helps with preparedness planning for extreme events (FEMA, 2015). Communities can work with universities to make sure that research is applicable to local needs. Such partnerships can be fruitful when there are several crucial players working with the data to identify solutions (check local university websites for potential resources and partnering opportunities).

This can include projections of the amount and location of development that may occur in a specified area as permitted by current land development ordinances. This information will inform stormwater managers regarding projected increases in impervious surfaces and the associated stormwater management needs.

This can help stormwater managers consider the potential needs associated with projected increases in impervious surfaces. Example resources include the U.S. Environmental Protection Agency's Integrated Climate and Land Use Scenarios project and USEPA's Impervious Surface Growth Model.

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. USEPA's SWC and SWMM-CAT provide regional downscaled climate projections. USEPA is also developing a web application for visualizing and downloading climate model output (the Global Change Explorer).

In addressing future precipitation changes in stormwater management, decision makers may need assistance determining which climate change scenarios to evaluate, where to get appropriate climate data and assessing whether the climate projections coincide with locally driven concerns.

Apply Green Infrastructure Strategies

A retention pond is one of the earliest prototypes of green infrastructure, 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 ironenhanced sand filter bench that removes dissolved substances such as phosphorus from 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.

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.

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. 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 green infrastructure practice such as a cistern or bioretention area.

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.

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.

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.

Consider the Cost and Benefits of Green Infrastructure

For example, work with the financial departments to establish an easy tracking and reporting protocol to collect data related to costs and savings of implemented green infrastructure projects. Improve documentation regarding project funding and actual costs. Build a database to inform future projects. Suggest funding organizations incorporate requirements for enhanced financial and impact tracking reporting in project selection.
(e.g., what a city spent on repairs and replacement of infrastructure following a storm; job and recreational losses due to damaged or destroyed infrastructure) to facilitate improved quantification of the costs and benefits of green infrastructure investments. Provide opportunities for information sharing that are specific to economic valuation. Webinars, workshops and tools can be used to disseminate existing knowledge and answer questions.
Train local appraisers/commissioners to capture the full value of green infrastructure. Incorporate co-benefits into ROI calculations, such as ecosystem services and quality of life factors.

Update or use existing tools including the U.S. Environmental Protection Agency's National Stormwater Calculator, the Center for Neighborhood Technology's Green Values National Stormwater Management Calculator and The Value of Green Infrastructure guide.

Examples that cover a range of municipalities with different budgets and populations are helpful for local practitioners to find and consult studies that are similar to their own communities.
This can include projects where green infrastructure provides a co-benefit with little to no added cost (e.g., providing Americans with Disabilities Act [ADA]-compliant sidewalk access, adding a swale for pedestrian protection that also collects rainwater).
Examples include the Connecticut Nonpoint Education for Municipal Officials (CT NEMO) Rain Garden App; provide information about the multiple ecosystem services provided by green infrastructure, such as the U.S. Forest Service's i-Tree tool that estimates ecosystem services from trees used for urban stormwater runoff control that also provide local cooling services.
Develop communication materials that can be used in conversations with different audiences (e.g., use common terminology to help nontechnical stakeholders better understand the value of green infrastructure).
Share information about the current status and the actual costs and values of projects that were implemented 10 or 20 years ago. Show how benefits and ROI have been realized through formats including videos or other readily accessible modes of communication.
Develop templates that can be used to assess how different green infrastructure methods and projects can work in an area and include cost estimation guidance.

Consider Stormwater Management Logistics

Municipal Separate Storm Sewer Systems (MS4s) transport stormwater runoff that is often discharged into water bodies. Since 1999, even small MS4s within and outside urbanized areas have been required to obtain National Pollutant Discharge Elimination System permit coverage. Jurisdictions with MS4s can include green infrastructure as a control measure. USEPA published a factsheet that discusses how green infrastructure can be integrated into stormwater permits and provides examples of communities that have done so.

Consider incentives such as fast-track permitting for projects that adhere to a more strict set of requirements (e.g., projects that manage 80% of runoff onsite or incorporate a green roof).

Consider regulatory changes at the federal or state level to minimize variance regarding stormwater infrastructure guidance and regulations among communities.

Bringing together relevant agencies, organizations and individuals responsible for stormwater management decisions from across watersheds can help address barriers presented by different regulations, budget limitations and expectations for growth. Representatives of water management, environmental, land use planning, public works, and transportation departments (among others) are important to include because each of these agencies plays a role in stormwater management.

Engage the full suite of agencies and departments, particularly at the federal level, that affect or could be affected by solutions to address changing climate conditions in stormwater management. Consider involving, for example, FEMA, the Army Corps of Engineers, Departments of Transportation, Parks and Recreation and State Departments of Ecology or Natural Resources. Also encourage a "no wrong door policy" (i.e., that data and information is shared across web portals and resources are shared across agencies). Seven federal agencies have come together with nongovernmental organizations and private-sector entities to support the Green Infrastructure Collaborative, a network to help communities more easily implement green infrastructure.

While development may be deterred when individual communities change local standards independently, potentially negative impacts could be avoided if surrounding municipalities agree to adopt similar policies.

Establish this protocol early in the project planning phase to avoid future confusion or mismanagement. For example, Washington, DC's Stormwater Management Guidebook (CWP, 2013), provides for a stormwater retention credit program for certification. To be eligible for certification, a best management practice must, among other criteria, provide a contract or agreement for ongoing maintenance and pass ongoing maintenance inspections.

Find ways that the state or county can provide incentives for regions to develop watershed-scale plans.

Incorporate green infrastructure and low impact development into existing plans, such as watershed implementation plans.

This may be more cost effective than developing individual plans.

(e.g., rain gardens, vegetated swales and other installations). This may also entail offering financial incentives in places where individual homeowners are responsible for installation and maintenance, to help individuals pay for the maintenance of this public good.

Request modifications (e.g., MS4, others) so that schedules are complimentary to efforts and the same/complimentary goals are being targeted for different projects. Also seek schedule variances for some reporting requirements (e.g., MS4, others), as needed, within a given community.

Examples may include comprehensive plans or watershed-scale plans. Determine the level of plan that may be the best scale at which to address climate change.

Use pilot projects or those with minimal barriers to explore collaboration among agencies.

Use Natural Infrastructure

  • Plant trees
    Water temperature benefits include shading the ground and keeping water temperature cooler. Other benefits can include controlling stormwater runoff and promoting infiltration.
  • 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.

  • Removing unneeded dams and impoundments
    Water temperature benefits include keeping impounded waters from heating up. Other benefits can include restoring natural hydrology, returning to natural sediment transport and geomorphology and reestablishing natural disturbance.
  • 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.
  • Create deep pools or artificial logjams
    Water temperature benefits include providing shade or deep water that limits direct heating from sunlight. Other benefits can include constructing biotic refugia or habitat and building biological communities.

  • Control groundwater withdrawal
    Water temperature benefits include maintaining groundwater sources that supply base flow to streams. Other benefits can include creating habitat and hydrological connectivity and restoring natural hydrology.
  • 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.
  • Remove unneeded channelization
    Water temperature benefits include restoring natural groundwater exchange and connection to floodplains which promotes floodwater infiltration into aquifers. Other benefits can include restoring natural hydrology, returning to natural sediment transport and geomorphology and reestablishing natural disturbance.

  • Plant forest and floodplain habitat
    Water temperature benefits include: shading watershed lands, surface waters and streambeds; reducing runoff; and promoting groundwater infiltration. Other benefits can include: creating habitat and hydrologic connectivity; rebuilding native vegetation and corridor networks; and raising water quality.
  • 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 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.

Build Staff Capacity

Conduct pilot studies and publish the results and lessons learned to increase awareness and provide specific examples of how alternative stormwater management solutions perform. One specific need is additional examples that quantify infiltration rates in different areas to supplement existing knowledge.

An ordinance can help local jurisdictions incorporate climate change projections or green infrastructure incentives into local legislation. For example, the City of Seattle developed a citywide model ordinance for stormwater management using green infrastructure

See more about Seattle's citywide model ordinance.

This will help to complement existing staff knowledge and expertise.

Offer incentives for engineers or contractors to use green infrastructure designs, rather than relying on pipe-based systems.

Training can help to better equip staff to assess green infrastructure proposals. For example, the U.S. Environmental Protection Agency offers a Green Infrastructure Webcast Series. USEPA and other federal agencies and nongovernmental organizations have formed the Green Infrastructure Collaborative, a network to help communities more easily implement green infrastructure.

Creating such a list can help connect experienced professionals with potential projects that could benefit from alternative design solutions.

Provide Public Awareness and Coordination

Adopt more stringent policies such as stormwater fees and requirements for developers to manage water onsite to the maximum extent feasible. Similarly, require developers to make decisions informed by future climate, and local governments to incorporate climate change into decision-making processes.

On-the-job training and continuing education opportunities, which can help to increase the climate literacy of existing staff and ensure timely application of research designed to address decision-maker needs. Also, use educational projects in schools or at community centers as opportunities to disseminate climate change information to the public.

Collaboration through activities such as tree planting or installing rain gardens can be an effective adaptation measure. In all work with individuals and community groups, be sensitive to hot button topics that may distract from the purpose of the conversation and the issues that the work intends to address. For example, if climate change is a highly political issue, it may be useful to steer the conversation towards observed and projected changes for specific endpoints of concern (e.g., changes in 25-year storm event or the intensity of brief downpours) or green infrastructure's cobenefits to a community's livability and economic vitality. Focusing on issues of vulnerability and future weather changes can help to move discussions forward and avoid some of the potential barriers that arise when using the term "climate change."

(e.g., interdepartmental meetings, workshops, webinars, online forums). Ensure that senior management is on-board and that the administrative and fiscal mechanisms of the city enable interdepartmental collaboration.

If the market offers innovative stormwater solutions or climate resilient developments that are attractive and effective, the public will more likely favor these best available options. A developer-driven solution may be most effective in an area that is rapidly changing. For instance, the recently developed Celebrate Senior Center in Fredericksburg, Virginia, is using 65 bioretention areas and 15 water quality swales to treat 43 acres of manicured landscape. Stafford County anticipates that this project will demonstrate that green infrastructure solutions can offer amenities that increase the value of the landscape while managing stormwater onsite.

These networks connect communities at varying stages of implementation and include the Great Lakes Adaptation Assessment for Cities (GLAA-C), Urban Sustainability Directors Network (USDN), American Society of Adaptation Professionals (ASAP) and the Great Lakes Saint Lawrence Cities Initiative.

Use redevelopment projects as onsite demonstrations of ways to adapt to climate change using LID, green streets, or environmental site design. Such demonstrations will make these approaches highly visible to the public, politicians, decision makers and project partners.

USEPA, as well as NOAA and other federal agencies provide tools, guides and case studies of green infrastructure projects conducted with a large number of communities across the country.

Source Documents

These strategies are adapted from the following existing website: U.S. Environmental Protection Agency, Centers for Disease Control and Prevention, and other federal resources. Please view these strategies in the context provided by the primary source document: