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Reimagining Urban Waterways: Arroyo Seco Channel Transformation



The Challenge

The Cities of Pasadena and South Pasadena faced a watershed moment - quite literally. With 5,005 acres of drainage area feeding into the Arroyo Seco channel, they needed to balance water quality objectives, flood control, and community desires. The challenge was clear: transform spaces along the channel into multifunctional assets that could capture stormwater, improve water quality, and enhance the urban landscape. This wasn't just about managing runoff; it was about reimagining the role of urban waterways in the face of climate change and growing community needs.


Our Approach

This project isn't just about two cities or one channel. It's a blueprint for how we can reimagine urban waterways as multifunctional green infrastructure. By integrating stormwater management with community spaces and ecological restoration, our goal was to set a new standard for urban water resilience. 


Here's how we're transforming the Arroyo Seco Channel:


  1. Optimization Analysis: We conducted our unique optimization analysis to determine the perfect balance of BMPs that achieve water quality objectives while maximizing return on investment.

  2. Community-Responsive Design: We listened to community feedback and relocated the infiltration basin to create a more natural design with shallower depths and room for passive recreation. 

  3. Multifunctional Solutions: Our design includes an infiltration basin to intercept flows from San Rafael Creek and rehabilitation of the existing San Pascual BMP, creating opportunities for groundwater recharge and water reuse.

  4. Ecological Enhancement: Native, drought-tolerant landscaping will improve aesthetics, provide wildlife habitat, and offer recreational spaces. 

  5. Innovative Water Reuse: Treated water from the San Pascual basin will be reused for irrigation at a nearby golf course. We're closing the loop on urban water cycles, making every drop count.


Key Takeaways

  • Large-scale impact: Managing runoff from a 5,005-acre drainage area

  • Community-centric design: Adapting plans based on local feedback

  • Multifunctional BMPs: Balancing water quality, flood control, and recreational needs

  • Ecological restoration: Incorporating native landscaping for habitat and aesthetics

  • Water reuse innovation: Treating and repurposing water for local irrigation


Project Highlights

Our optimized system includes:


  • San Rafael Creek infiltration basin for groundwater recharge

  • Rehabilitated San Pascual BMP with added outflow filter

  • Arroyo Seco channel diversion improvements

  • Native, drought-tolerant landscaping for aesthetics and habitat

  • Water reuse system for nearby golf course irrigation

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