Incorporating Climate Change into the San Lorenzo Watershed Management Plan
In 2008, the Board of the San Lorenzo Valley Water District approved a climate change resolution committing the District to reduce greenhouse gas emissions and consider the impacts of climate change in all planning documents. The Master Water Supply and Management Plans discuss how climate change will impact local water resources. Climate change is expected to cause drier and shorter wet seasons regionally, making both water conservation and efficiency priority issues for water managers.
In April 2008, the San Lorenzo Water District (SLVWD), in collaboration with nearby water districts, sponsored a local forum titled “Tools for Addressing Climate Change and Local Water Resources.” The forum addressed three key questions:
- What are the potential impacts of climate change on local water resources?
- How can local water managers plan for these impacts?
- How can local water agencies reduce their carbon footprint?
After the forum concluded, the SLVWD Board of Directors approved a climate change resolution mandating that all future documents and plans address climate change impacts, and mitigation and adaptation opportunities.
To assess the vulnerability of the SLVWD to climate change, the District first turned to global climate models to ascertain projected regional changes. The climate models presented a drier and shorter wet season with a 3-10°F increase in annual temperatures by 2100. These findings indicate that the total amount of water available statewide will decrease, water demand will increase, and the timing of water availability will be altered. To design a water management plan capable of addressing climate change, the SLVWD reanalyzed historical hydrological conditions and water production records dating to 1984 during which the SLVWD incurred two droughts. This analysis was then extrapolated to 2030 to infer the potential effects of climate change on water resources, assuming that future climate variability reflected historical norms. By 2030, without any supplemental water resources, the Southern Service area of the SLVWD may not have enough water to fulfill water resource demands. However, it is expected that the Northern Service area will be more resilient to climate impacts; therefore, if the Northern and Southern Service areas could be connected (an “Intertie”), some future problems could be averted.
To help the SLVWD in decision-making and to prepare for changes in water resources, two scenarios were presented:
- Use supplemental water only when needed to supply the Northern Service area which would then secondarily supply the Southern Service area.
- Routinely access supplemental waters to recharge groundwater supplies even when water demands are being met.
Ultimately, scenario 2 was recommended because it allows the SLVWD to access and utilize supplemental waters to recharge groundwater reservoirs and will lessen the likelihood that the SLVWD is in direct competition with other water districts during periods of drought.
In 2010, SLVWD released Part II of the Watershed Management Plan, which outlines the goals, objectives, and policies related to the District’s approach to watershed management. Part II also includes a section on local climate change and SLVWD’s role in addressing climate change. In 2012, SLVWD released a site-specific management plan for the Olympia Watershed property (Part III). This plan reviews existing climate conditions for the site, mitigation and adaptation options, opportunities and constraints, as well as climate change management alternatives. Adaptation priorities include addressing water supply issues and protecting watershed ecosystem functions.
Outcomes and Conclusions
The SLVWD is funded primarily from water service fees from its customers. In 2017, SLVWD directed staff to prepare a climate action plan, although these efforts have yet to be completed.
Feifel, K. (2020). Incorporating Climate Change into the San Lorenzo Watershed Management Plan [Case study on a project of the San Lorenzo Valley Water District]. Version 2.0. Product of EcoAdapt's State of Adaptation Program. Retrieved from CAKE: https://www.cakex.org/case-studies/incorporating-climate-change-san-lorenzo-watershed-management-plan (Last updated October 2020)