California water use and availability is “not sustainable”. Due to recent rainfall, we have an abundance of water available. But, it’s important to remember that Southern California is a desert and it won’t be long before we see drought conditions again. Rather than wait for supplies to deplete, it’s important that we take necessary steps to conserve and use water wisely.
Panelists were brought together to cover this topic from a variety of angles. I was there to focus on the many design solutions that can be used to meet the new legislative requirements for a variety of property types, including retail, commercial, hotel, parks and residential. Joining me on the panel were Ian Adam (Fuscoe Engineers), Commissioner Paula Daniels (author of the LID Ordinance), and Marsha Prillwitz (AB 1881 background and adoption). The following were key take-a-ways from the panel discussion.
- AB 1881 is a statewide Model Ordinance. Therefore, it is up to local jurisdictions to determine whether it makes sense to adopt it. Local jurisdictions were given the option of adopting the Model Ordinance, creating their own ordinance that meets 1881 goals or demonstrating why they should be exempt based on local climate and water-use history. For this reason, many jurisdictions have their own set of requirements.
- LID should be officially approved in the next couple weeks and effective next year.
- In Southern California, potable water is a luxury. One third of Southern California’s water supply is imported from Northern California and its route includes the biggest lift in the world over the Tehachapi’s. In the event of a large earthquake, the Northern California water supply could be at great risk. Additionally, Los Angeles is fortunate to have a water basin. San Diego does not have one and must rely on recycling and desalinating water. In Los Angeles we have the option to recharge the water table. For these reasons, Daniels believes LID is critically important to the future of LA’s water supply.
- The LID Ordinance offers solutions by priority: starting with infiltration, then capture and re-use and last high efficiency filtration. The first is the best option for retaining the first ¾” of rainfall onsite as required by the ordinance. Should a property be unable to meet the requirement using those three options, they can capture water off-site i.e. medians and public parkways or as a last resort fall back to SUSUMP requirements.
- The viability of greenroofs was debated. New technology is being developed quickly and there are new options out there that would solve some the past challenges of installing greenroofs in Southern California. Challenges include reliance on irrigation to supplement the lack of steady rainfall in our region and fire hazard concerns from utilization of low water-use plant material. Rooftop succulent gardens are one option with new materials being developed that retain and evenly distribute water more efficiently. More innovation on the technology-side is needed to make greenroofs a go-to option in Southern California.
For the benefit of those who were unable to attend the session, below are the design recommendations I presented for each ordinance:
Water Efficient Landscapes -1881
1. Pick Right Plants for the Right Uses (Improve Plant Selection)
- Native revegetation on Slope Projects
- Hydrozoning plant material
- Synthetic turf and groundcover as turf substitute
- Community Vegetable Gardens
- Roof Gardens
- Rain Gardens
2. Pick the Right Irrigation for the Right Place (Improve Irrigation)
- No overhead within 24” of hard surfaces
- Set maximum applied water use for each site
- No run-off or low head drainage
- Reclaimed water use and/or Rainwater Storage and Use
- Utilize new technology in irrigation equipment (Smart Controllers)
- No Spray Irrigation in areas of 8’ or less
- Precipitation rates of 0.75” per hour or less
3. Grading / Soil Management
- Mulch to retain soil moisture
- Design low lying areas for water infiltration
- No turf on 4:1 slopes or greater
- Design permeable hard surfaces
- See LID for more detailed descriptions
A Variety of Solutions -LID
1. Reduce Stormwater Runoff
- Permeable Paving
- Retention Basins
- Promote Rain Harvesting
- Roof Gutter Drain into Planter Areas
- Roof Gardens
- Mitigate Offsite to handle onsite impacts
2. Improve Water Quality
- Planted Bioswales
3. Improve Groundwater Recharge
- Rain Gardens
- Infiltration Structures
4. Reduce Offsite Erosion
- Keep .75” Storm Event on site
- Curb and Gutter Drain into Bioswales
- Slope revegetation with non-irrigated natives