Restoring Neighborhood Streams: a book that LA could use
February 19, 2018 § 9 Comments
Creekfreaks! If you, like me, have resolved to pull away a bit from the netflix-amazonprime-hulu bingefests that serve as a daily nonpharma escapist (are we really living these political times?) opiate, and if maybe you, like me, are rediscovering those magical things called books – then I have a few reads for you! They range from practical, to lyrical, to celebratory. Personally, I find them all inspirational. In today’s post, I give you –
The Practical: Restoring Neighborhood Streams; Planning, Design, and Construction
Restoring Neighborhood Streams; Planning, Design, and Construction (2016, Island Press), builds on author A.L. Riley’s decades of engagement and effort in the restoring and daylighting of streams in urban and suburban areas. This Creekfreak was especially influenced by Riley and her work. Her previous book, Restoring Streams in Cities, is well dog-eared in my library, and has been an important go-to reference for how to think about stream function and restoration design. This new book provides case studies that illuminate fundamental questions that should be the basis for planning and design of urban stream restoration:
- Is it physically feasible to restore?
- Is it financially feasible?
- Does the public support (I’d add: political will) exist to support land use changes to support a live river or stream?
In my 12 years of thinking, advocating, developing feasibility studies and even doing conceptual design for restored urban streams in the greater Los Angeles area, I found that the first two of these questions for quite a few streams – somewhere on their reaches – can be yes. The third question, however, has been challenging in our region (with two delightful exceptions – one in which I had a subconsultant role, and here’s the other, no personal role, just admiration). Riley’s book, then, is an important tool to break down some barriers in understanding, provide a common vocabulary for discussing urban stream restoration, and frame a solid, tested approach for “improving” urbanized river corridors.
While the book focuses on “neighborhood scale” stream projects, Riley does dedicate some space early in the book to ruminate on the restoration issues and opportunities of the Los Angeles and San Gabriel Rivers. Noting that engineers have long declared restoration here impossible, she observes functioning stretches of earthen-bottom river (such as the beloved Glendale Narrows, and parts of Coyote and San Jose Creeks), complete with a wide range of sediments and sufficient geomorphic development to support riparian habitat:
“they (these reaches) provide a model for removing concrete channel inverts along the other reaches of the river…Short floodwalls can be added to the higher terrace to contain the expected higher water-surface elevations for the largest flood flows…Concrete reaches can emulate the dirt-bottom sections with removal of the concrete invert and use of grade controls to support the concrete sides while allowing the river to have a functioning ecosystem…”
If this sounds at all familiar to people who have seen my talks and posts over the years – credit Riley’s mentoring. Keen observers may also note that this description doesn’t quite sound like the favored Alternative 20 in the LA River Ecosystem Restoration Feasibility Study or the gist of the Los Angeles River Revitalization Plan. It’s not. While Alt 20 proposes creative means to substantially increase habitat, it does this not through reestablishment of geomorphic processes of the LA River but through many top of channel and out-of channel improvements, including creek-like constructions (some indicated as stormdrain daylightings), terracing of the river’s concrete channel to enhance access, and some areas of widening of the river where it already has an earthen bottom. It does include some additional naturalization at the Verdugo and Arroyo Seco confluences – but large swaths of the 51 miles of concrete channel bottom were not considered or proposed for naturalization. The difference in approach does also call to mind this comment in the book:
“…(A) restoration project based on the general public’s perception of river health – that of a tidy greensward park – can preclude the public’s understanding of the importance of river environment processes such as flooding and erosion that maintain the “messy” river characteristics responsible for ecological functioning. A segment of river may meet many people’s expectations of a healthy river if the water is clear and the stream banks are not eroding. If this “tidy” appearance comes at the expense of ecological functioning, however, the hydrologic and geomorphic processes may no longer create and maintain the disturbance regime necessary to support ecological integrity.”
Had this book been a reference for the river planning process, one might imagine a plan that charted a path towards riparian function and connectivity up and downstream, anadromous fish recovery, and floodplain reconnection – with landscape enhancements for public access. It would be a different conversation than the one started by Frank Gehry, that’s for sure. But back to the book….
As Riley walks readers through actual restored and daylighted stream examples, she narrates the political, social, technical, and financial considerations that were addressed with each project. The restored streams find themselves now in street medians, parks, school playgrounds, and housing developments – messy and free streams that attract wildlife, enhance water quality, and potentially recharge groundwater. And that enhances the neighborhoods in which they flow – and that people enjoy. The book concludes with a discussion of restoration tools and strategies to help you plan your restoration projects – like our Los Angeles River?