Economics of Stormwater Capture and Its Multiple Benefits

Date / Time:
Tuesday, Sep 15 2:35pm to 3:05pm
Track / Session:
Track: Funding and Financing / Session 3
Short Description: 
Incorporating multiple benefits into economic evaluations demonstrates that stormwater capture is economically feasible and can provide opportunities to build co-funding partnerships.

Stormwater is an increasingly important and undervalued water supply option in California. Yet, stormwater management remains underfunded throughout the state. As climate change increases the risk of both droughts and floods, stormwater capture offers a significant opportunity to invest in stormwater management generally, while improving water sustainability and community resilience.

Purpose and Engagement: In this presentation, we will outline the key findings from our recent research on the levelized cost of stormwater capture in California and highlight opportunities for stormwater managers to co-invest in stormwater management to simultaneously address water quality, flooding, and water supply.

Our research demonstrates that stormwater capture investments may be more economically feasible than expected and can support co-investments among water and non-water agencies (See: Cooley, et al., 2019; Diringer, et al., 2020). In addition, we will describe a path forward for stormwater managers, including incorporating multiple benefits into water management partnerships and decisions. To engage the audience, the presentation will include on-the-ground examples for stormwater managers and highlight resources available for incorporating multiple benefits into their own work.

Summary of Tools, Ideas, and Concepts: In our recent research, we evaluated the levelized cost of 50 proposed stormwater capture projects in California, characterizing the projects by water source, process, and water supply yield. In addition, we incorporated co-benefits of projects into the analysis to examine the net benefit of proposed projects. When incorporating the reported co-benefits of the projects, the expected levelized cost of these projects decreased dramatically. For projects that reported even a limited number of additional benefits, the net levelized cost of urban stormwater capture decreased from $1,030 per AF to $150 per AF, with some of the projects demonstrating a net benefit.

In addition, we examined the project beneficiaries to highlight opportunities for cost-sharing among public agencies. While the projects examined were primarily driven by flood control and water supply, there were substantial opportunities to leverage additional funds through the co-benefits provided. In summary, inclusion of additional benefits will simultaneously provide a better understanding of net benefits of water management and opportunities for developing partnerships around shared outcomes.

In collaboration with a diverse group of stakeholders, the Pacific Institute has developed a framework for incorporating multiple benefits into water management decisions (See: Diringer, et al. 2019). Using stormwater capture as an example, we will highlight how to identify, evaluate, and communicate the multiple benefits of stormwater management to build co-funding partnerships and leverage funds for community and environmental benefits.

Conference Theme: As we “envision the future,” stormwater capture can capitalize on periods of intense rain and advance water supply reliability while improving water quality, reducing flood risk, and providing important environmental and community benefits. In turn, these co-benefits can help leverage essential funding toward stormwater management that can support healthy waterways and communities.

Cooley H, et al. (2019). The cost of alternative urban water supply and efficiency options in California. Environ. Res. Commun. 1 (2019) 042001.

Diringer SE, et al. (2019). Moving Toward a Multi-Benefit Approach to Water Management. Oakland, Calif.: Pacific Institute.

Diringer SE, et al. (2020). Economic evaluation of stormwater capture and its multiple benefits in California. PLOS ONE 15(3): e0230549.

Primary Speaker:
Sarah Diringer, Pacific Institute