FAQ: Arboretum Waterway Flood Protection and Habitat Enhancement Project

Frequently Asked Questions

Phase two of our multi-year Arboretum Waterway Flood Protection and Habitat Enhancement Project will begin in Fall 2022. Phases three and four will be constructed in Fall 2023. Below are a set of questions that are frequently asked about this project; we hope you find them helpful. Learn more

  • What are the different phases of the project?
  • The Waterway project was designed in phases to allow for implementation over time, while leaving portions of the Waterway wet for wildlife and visitors. See the diagram of the phases.
    Phase 1  Phase 1 starts at the east end of the Waterway, near downtown, and continues through the Redwood Grove to Wyatt Deck Bridge. Construction of this phase was completed in 2017 with revegetation in 2018.
    Phase 2 
    Phase 2 starts where Phase 1 ends, encompasses Lake Spafford and continues to the Native American Contemplative Garden. We expect to begin construction here in summer of 2022 with revegetation following in winter and spring of 2023.
    Phases 3 and 4 – Phases 3 and 4 start where Phase 2 ends and continue to the west end of the Waterway. These phases will be under construction in the summer of 2023, with revegetation following in winter and spring of 2024.
  • Is the Arboretum Waterway the same as Putah Creek?
  • No, the Arboretum Waterway is a pond located in the historic channel of the North Fork of Putah Creek.  It used to be part of the historic, natural Putah Creek, but starting in the 1870s the creek was diverted to the south of campus and city of Davis to prevent frequent flooding of local farms. That is why the Arboretum Waterway is considered part of the historic channel — it is a relic of what used to be. Now, the Arboretum Waterway is essentially a man-made pond — both ends are dammed, its water flow manipulated, and the banks sculpted. It is the lowest spot on campus and now functions as a basin for capturing storm water. All central campus storm drains empty into the Waterway. To prevent campus flooding, excess water spills over a weir on the west end; it is then pumped through a pipe to the natural Putah Creek and eventually meets up with the Sacramento River. This flood prevention system only indirectly connects the Arboretum Waterway to Putah Creek.
  • Why is the Waterway green?
  • Algae makes the water look green. Algae is a natural part of water bodies in the Central Valley of California and many other places around the world. These photosynthetic aquatic organisms thrive in the Arboretum Waterway because of the conditions the Waterway provides: warm, slow moving, nutrient rich water.
  • What changes will occur with this project?
  • Similar to the first phase of the project, located from the east terminus of the Waterway to Wyatt Deck Bridge, the future phases will have several outstanding features. The banks will be transformed from crumbling concrete to earth slopes with native plants that gradually enter the water. Weirs will be added to create elevation changes within the Waterway that, with the addition of a re-circulation pump, will create continuous water flow throughout the Waterway. Emergent marsh vegetation will be planted next to the weirs and along the banks, creating a more natural look to the Waterway. In some places the channel will be narrowed to create wetland habitat and reduce water residence time. (See also the FAQ below: “How will the improvement be accomplished?”)
  • Where did you get the idea for this design?
  • The inspiration for the design of the Waterway is Putah Creek which you can still find as part of the campus’s Putah Creek Riparian Reserve located on south campus. Like Putah Creek, there will be vegetation along the Waterway, as well as in the water including some naturally-occurring duckweed and algae, albeit in much smaller amounts. (To learn more about the Arboretum Waterway’s history and lack of connection to Putah Creek read the first FAQ “Is the Arboretum Waterway the same as Putah Creek?”)
  • Why are we doing this project now?
  • We are redesigning the Waterway to function better from a storm water collection standpoint, as well as from an ecological and aesthetic standpoint. This redesign prepares for the impacts of climate change, protects campus from flooding, and creates research, education and professional training opportunities. With funding secured, now is the time to complete this project.
  • How will the maintenance and enhancements be accomplished?
  • Dam creation – Within the Waterway, temporary coffer dams will be installed and the water within the damned area will be pumped dry. Fish and turtles will be moved to the other side of the coffer dams where there is still water. This will take place under the supervision of a wildlife biologist.

    Concrete edge removal – The concrete edges will be removed and replaced with gentler slopes to be vegetated with California native plants. These plants, with spreading rhizhomes and deep roots, will prevent erosion, filter sediment and provide wildlife habitat.
    Earth Work – After the water is pumped out of the project area, soil will be moved within the channel to reshape the contours of the Waterway.
    Weir building – Additional weirs will be constructed, giving an additional 15-inch drop from the Lake Spafford to the far west end of the Waterway. The elevation difference will allow the water to cascade over the weirs, keeping the water flowing and creating conditions that are less favorable to algae and duckweed growth. After the Waterway is dredged and rough graded, these weirs will be constructed. Some weirs will be concrete with a steel lip over which the water will flow. Others will be built using rocks as part of our Waterway Stewardship Learning by Leading™ student internship. Only about six inches of the weir will be visible above the water, so they will be small relative to the creek banks.  Both upstream and downstream of the weirs, there will be emergent marsh plants installed, creating a soft, natural look.
    Pump installation – The water re-circulation will be made possible through the installation of a series of pumps and underground water lines. The pumps will be in a vault and will not be audible.
    Bank building – Some parts of the banks will require additional soil to create gentle slopes along the water edge, suitable for planting. This soil will also provide a place for emergent marsh plantings to grow at the water’s edge.
    Plant establishment and care – Vegetation will be planted upstream and downstream of the weirs, including along the re-graded banks and newly-created floodplains. This will be emergent marsh and wetland vegetation at the water’s edge to protect against erosion and provide habitat. The plants along the banks of the Waterway will be installed as part of our student Learning by Leading Program. There will also be opportunities for community plantings. Prior to construction, some areas of the banks will need to be cleared of vegetation, some plants will be transplanted, and some trees will be pruned to allow equipment access.

  • What can I expect during construction?
  • During construction, some lower pathways will be inaccessible. Detours for bikes and pedestrians will be in place. There is the possibility of some odor of decaying material as the work area is drying out. Through the use of pumps to remove the water quickly, odors will be minimized by speeding the drying.
  • When is construction starting?
  • The construction time frame for phase 2 of this project is Summer 2022 through Fall 2023, with revegetation in the Winter and Spring of 2023. Phases 3 and 4 will be constructed in summer 2023, with revegetation in the Winter and Spring of 2024. However, multiple variables outside of our control affect this timeline. We will keep you informed of our progress and any changes to these dates via our email newsletter, The Leaflet. Sign up to receive it here.
  • What is going to happen to the wildlife?
  • The wildlife that can’t move on their own, such as fish, turtles, and crayfish, will be moved — under the supervision of wildlife experts — to parts of the Waterway that will still be filled with water during construction. Birds, including ducks, and other wildlife that can move quickly on their own will migrate to adjacent areas naturally. An exclusion fence will prevent turtles from re-entering the construction area. After construction is complete, animals will naturally repopulate the restored Waterway.
  • Where does the funding come from?
  • The financing for this project is through $5.4 million in Proposition 68 funding through the California Natural Resources Agency, with a $2.5 million campus match.
  • What is the long-term plan for the Waterway?
  • The long-term plan is to create an emergent marsh, open water, and riparian forest habitat area which will increase the wildlife habitat dramatically. The area will be stewarded for plants, wildlife, and flood protection. The west end of the Waterway project area is also planned to have a boardwalk and viewing platforms, for which we are currently raising donor funds.
  • Where can I find out more information about this project?
  • Online: Updates about the project will be available on the UC Davis Arboretum and Public Garden website at arboretum.ucdavis.edu/waterway.
    Email: To stay informed about this project and its progress, as well as future phases of the Arboretum Waterway Flood Protection and Habitat Improvement Project, please be sure you are signed up to receive The Leaflet, the UC Davis Arboretum and Public Garden’s email newsletter.
    If you have any specific questions about the project, please contact Andrew Fulks at amfulks@ucdavis.edu.
  • How can I help?
  • Volunteer: After construction is completed, Arboretum and Public Garden staff, student interns, and volunteers will plant and care for wetland plants along the edges of the Waterway.
    Become a member: The Friends of the UC Davis Arboretum and Public Garden, our member non-profit organization, supports the ongoing work of the Arboretum and Public Garden, including horticultural, curatorial, and educational programs. Becoming a member helps fund the improvements to our gardens and collections, as well as our programs. Learn more about becoming a member and the many benefits.
    Stay in touch: Learn more about the Arboretum Waterway Maintenance and Enhancement Project, volunteer opportunities and more by signing up for our email newsletter here.