1. “Drowning in the Desert” Revising the urban stream syndrome for the arid Southwest US

2. Stream hydrology controls stream health Poff et al. (1997) “The natural flow regime” Bioscience 47: 769-784

3. Natural ground cover 10-20% impervious 35 to 50% impervious 75 to 100% impervious Impacts of Impervious Surface From National Research Council (2008) “Urban stormwater management in the US”

4. Natural ground cover 10-20% impervious 35 to 50% impervious 75 to 100% impervious Impacts of Impervious Surface From National Research Council (2008) “Urban stormwater management in the US”

5. Natural ground cover 10-20% impervious 35 to 50% impervious 75 to 100% impervious Impacts of Impervious Surface From National Research Council (2008) “Urban stormwater management in the US”

6. Natural ground cover 10-20% impervious 35 to 50% impervious 75 to 100% impervious Impacts of Impervious Surface From National Research Council (2008) “Urban stormwater management in the US”

7. Increased imperviousness leads to… 1: Too much water being delivered to streams during storms 2: Too little infiltration and not enough baseflow during dry weather 1+2: “URBAN STREAM SYNDROME”

8. Reversing the urban stream syndrome Install distributed systems to capture/retain stormwater runoff and then… Reuse runoff in the home (e.g., toilet flushing) Infiltrate runoff to restore base flow Return runoff to atmosphere through evapotranspiration (e.g., green roofs, biofilters, constructed wetlands)

9. Reuse runoff in the home (e.g., toilet flushing) Conflicts with DHS guidelines (concern over cross-connections) Public health concerns Practicality—in southern California runoff is intense and short lived, toilet flushing goes on forever

10. Infiltrate runoff to restore baseflow Makes sense in many areas of the world Makes sense in some areas of Southern California – Deep groundwater recharge for drinking water supply BUT, baseflow in urban streams in southern California has INCREASED, not decreased over the past 100 years* – Infiltration may not be appropriate in many areas *Townsend-Small, Pataki, et al (2013) “Increasing summer river discharge in southern California, USA, linked to urbanization” Geophysical Research Letters 40:4643-4647.

11. Return runoff to atmosphere through evaporation/transpiration Green systems (green roofs, biofilters) are great but… – Concerns over long term maintenance – Plants with high ET are also unlikely to survive during prolonged dry weather Perhaps there is a role for “Wet systems” that promote evaporation (e.g., fountains, cooling systems) when needed, but can be shut off when not needed

12. Vision for Prop 84 Proposal Grand Goal: Make UCI a Zero Discharge Campus by 2020 Requires massive stormwater storage capability (up to 1500 acre feet per year) Requires new infrastructure for using the stormwater runoff Build a test facility on the UCI campus for innovative approaches to evaporate stormwater