Los Angeles Basin Study Summary Report

Changing demographics, climate change, and competing interests for available water supplies all present long-term risks to the stability and reliability of the region’s imported water.  The region recognizes that today’s challenges require an integrated water resources management approach.

For decades, this region has operated and maintained one of the most effective flood control systems in the world that protects millions of people from the impacts of flooding in the region. This system sends much of the stormwater runoff into the ocean, water that historically recharged local groundwater basins, making this region even more dependent on imported water supplies. As regulatory pressure to clean up polluted stormwater runoff continues and imported water resources diminish, this local source of water supply is becoming more and more attractive (GLAC IRWMP 2014).

Many of the region’s water management agencies have studied and planned for increasing use of local recycled and graywater supplies, ocean and brackish desalination, developing more groundwater, and implementing improved water conservation initiatives to extend existing supplies. Additionally, social trends and concerns also drive the emphasis on the use of local water supplies.

However, the one major local resource that has not been studied in-depth is stormwater and its opportunities to optimize the reliability of local supplies.

To enhance the capabilities of the existing stormwater conservation infrastructure within the Los Angeles Basin, the LACFCD began to investigate long-term projected needs and future climate conditions within the region. Given that local groundwater plays such a vital role in the region’s water supply portfolio, detailed scientific, engineering, and economic analyses were conducted to identify strategies for enhancing stormwater capture for groundwater recharge.

The LA Basin Study examined the region’s water supplies and demand, and impacts from projected population growth and changing climate in the watersheds of the Los Angeles region. The objectives of the study were to:

• Use state-of-the-art climate change analysis to develop projections of future water supply and demands in the Basin.
• Analyze how the Basin’s existing water infrastructure and its operations will perform in the face of changing water realities.
• Develop and highlight opportunities to adapt to current and future water demands.
• Conduct a trade-off analysis of identified opportunities.

Concepts ranged from enhancing the existing stormwater capture system and modifying existing facilities (including those capturing runoff for groundwater recharge), to developing new structural and nonstructural concepts that could help resolve future water supply and flood risk issues.
This Summary Report presents highlights of the critical tasks associated with this Basin Study and the results and findings produced throughout this collaborative study effort.

Full study chapters and appendices:

Plan of Study

Fact Sheet

Task 2: Water Supply and Demand

Task 3: Climate Change Analysis

Task 3.1: Development of Climate-Adjusted Hydrologic Model Inputs

Task 3.1:  Climate Change and Hydrologic Projections Appendices

Task 3.2:  Hydrologic Modeling Report

Task 3.2: Annual Hydrologic Results Workbook

Task 4: Existing Infrastructure Response & Operations Guidelines Analysis
Final Report

Task 5: Task 5 – Infrastructure & Operations Concept Analysis
Final Report

Task 6: Trade-off Analysis
Final Report

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