Uncovering, Enacting, and Adapting the Region’s Most Impactful and Resilient Stormwater Solutions

What is the preSIP?

We all want cleaner water and a healthier L.A. River. The preSIP study helps us get it sooner and more affordably by:

  • Using science and technology to uncover the best stormwater projects
  • Engaging stakeholders through a collaborative and iterative process to incorporate their goals and projects
  • Crafting an adaptive framework to make the watershed healthier over time

The preSIP is funded by $2.3M from the Safe, Clean Water Program to support smarter, collaborative planning that will provide a shared, transparent vision of where the watershed is and where it is headed.

Find Great


Plot a Clear

Design a Living

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Funded by the Safe, Clean Water Program. Access additional study reports here.

Why do we NEED the preSIP?

We know from experience that well-crafted plans can save our Cities and citizens millions of dollars!

The 2020 EWMP Adaptation Pilot Study demonstrated that by using the most up-to-date scientific understanding in the watershed and strategically placing stormwater capture projects where they are most impactful, the ULAR Group can get to a clean L.A. River at a substantial savings over previous planning approaches and recommendations. See chart below for projected Pilot Study savings by using the most project-oriented approach.

Taking this approach to the full watershed scale will require a unified approach among all of the ULAR Group’s Cities and partners. The preSIP will link all stormwater projects in the watershed through a platform that can support both understanding how far the watershed has come to this point and testing out new project ideas that will ensure its health for the future.

Pilot Study Results: Total Project Cost by Type

Compared to EWMP Capital Cost

Chart of Project Cost by Type compared to EMWP Capital Cost
Chart of Project Cost by Type compared to EMWP Capital Cost

Outcomes from the Pilot Study showed that project-focused infrastructure planning could produce the same outcomes at 27% of the cost of original EWMP estimates for the assessment watershed. IMAGINE what this means for the full L.A. River!


Constructed and Planned Projects have been Inventoried

The dashboard above is a glimpse into the inner-workings of the preSIP. All existing, constructed, and planned stormwater projects in the watershed have been accounted for to determine the baseline state of the watershed. These projects will be evaluated alongside a comprehensive accounting of all other project options to identify the ones that are the most impactful and cost-effective. Watershed managers will then be able to test out different combinations of these projects in an interactive way to envision the path to compliance that fits best. This will provide transparent accounting that can be evaluated both locally and watershed-wide to provide clarity in planning and an understandable path toward compliance.

What will the preSIP look like?

Simply put? A cleaner L.A. River.


While most of the details will take place behind the scenes, the preSIP will ultimately result in adaptive planning processes that ensure that year in and year out, the ULAR Group will be advancing the watershed to a cleaner future using the latest-available science and data, a unified planning/tracking platform, and the best multi-benefit stormwater projects throughout
the watershed.

In Partnership with the following:

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