Reconnections: Urban Runoff from Rooftops and Roadways to the Sea

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by Eddie Harris, Santa Barbara Urban Creeks Council

A recent email from Margie Bushman alerted me to the pervious concrete driveway pour at Owen Dell and Melanie Yanke’s house. I had heard about this method of using familiar materials to construct parking surfaces in a way that allows percolation of runoff into the substrate, and I was interested in learning about it. Owen and Melanie live near me on the mesa, so on the day that the pour took place I made sure I was there. I wore an old pair of levis and took along a pair of gloves, only because my experience has been that a scenario of this type is likely to result in my participation as a laborer, in setting forms, or as a finisher or cleaning up. This was not the case at Owen and Melanie’s pour. They had everything all formed and ready for the pour, and a crew of professionals was on hand to do all of the work. Along with local landscape architects, and restoration professionals, contractors, and folks from local agencies, I just watched and learned. This was the first use of pervious concrete for a residential project in the state, and Owen used the opportunity to educate the community. Two weeks later, when the concrete had cured, I went back to watch as maximum water pressure was applied to the driveway from a garden hose to demonstrate its capacity for absorption. It leaks like a sieve. If you have not yet seen how pervious concrete instantly sucks up water and delivers it to underlying soils, you may want to contact Owen for more information, or for a demonstration. Access his website at www.owendell.com/watershed.html, or email him at This e-mail address is being protected from spambots. You need JavaScript enabled to view it . And if you want to learn more about how pervious concrete might be used as part of a comprehensive watershed planning approach to solving serious problems within the urban topography, I invite you to read on:

The narrative actually begins about a century ago, when people arriving in Santa Barbara and throughout California from other regions of North America began to create hard surface improvements without first understanding the land where they had chosen to settle. They knew that land was cheap, and that the climate here was comfortable, but they did not understand that water was a scarce commodity that needed to be carefully managed. They knew that fertile soils here supported a range of vegetation from coastal wetland plants to native grasses and coastal sage scrub, and chaparral and oak woodland to lush riparia. But they did not understand that soils and plant communities and the anadromous steelhead trout that were numerous in the coastal streams depended on infiltration of infrequent and random rainfall across the full expanse and breadth of each watershed. The structure of the land, and hydrologic function within each of the various watersheds were not to be well understood until much later.

And so people began to pave, and for many years this seemed like a quite reasonable thing to do. Concrete and asphalt were the preferred materials that they used, because both were inexpensive and readily available, and they solved immediate problems. Concrete and asphalt could be used to efficiently rid the land of the nuisance of runoff from infrequent storms, and both were quite suitable for driving and parking motor vehicles on, as people and the economy of the nation became dependent on the automobile. Subsidized highway systems brought more people, and the paving continued. A point was reached where the land could no longer absorb and store and move water in the way that had been defined over eons by geological processes and gravity, and in the way that all living things had come to depend on. The hydrologic system, being out of balance, began to behave in ways that confounded the people who lived here. Fish disappeared. Aquatic systems began to smell bad. Creeks became fouled nuisances. Their banks also began to become armored with concrete, and some were placed underground in conduit. Much of the wetlands were filled. We are just beginning to realize the seriousness of these mistakes; the tragedy wrought by a century of paving.

Today people across the south coast are asking tough questions about how to repair important natural systems. Some like Owen and Melanie are experimenting with solutions. All of us know plenty of good reasons why groundwater stores and streams and coastal systems should be rehabilitated. Among these reasons are: Clean and sustainable water resources for human use, clean recreational waters, productive fishing resources for food, support of a complex food web and habitat for many important species, as well as flooding safety and aesthetic and passive recreational needs. These are the necessary services and benefits that healthy, functioning aquatic systems provide.

Can aquatic resources be made to function once again, at least to a level that sustains basic services and benefits that are important to our survival? With people like Owen and Melanie to show us the way, and with innovative use of materials such as pervious concrete, there is a reason to believe that positive change can take place, over time. With careful and comprehensive watershed master planning by local agencies, there is reason to think that important options can be left open, specific actions can be planned for, and that one day watersheds will recover.

The use of pervious concrete can make a substantial contribution to recovery, if its use proliferates as building material for outdoor parking areas, walkways, and perhaps curbs and roadways. But it is only part of the solution, and it does have limitations. For example, its effectiveness is limited by the permeability of the soil that underlies it. It should be applied over porous soils such as sandy loam, or other porous bedding materials in order to be of benefit in transferring runoff from rooftops and roads into the ground. Also, its performance is diminished if its porous spaces become clogged with sediments. So it may not be a good choice if used in a location where it will receive sediment laden floodwaters. But as part of well planned landscape or infrastructure design, it presents a number of creative options. It can be used to capture water from the sky, or runoff from downspouts, and to distribute that water directly into the soil, or via a french drain, into a bioswale or garden, or parkway.

Pervious concrete is only one of several options that can be used to recharge groundwater. Other options may be more suitable for a particular site. Bioswales, for slowing and retaining runoff are an ideal solution where there is room for their use. In addition to recharge of groundwater, a bioswale also performs biofiltration, removing pollutants that may be present in runoff. Bioswales also can be complementary to gardening and landscaping design throughout our arid region. Dry wells and cisterns are other choices that can help to retain water and slow the release of runoff into the soil. These are all solutions that will help to balance the hydrologic deficit over time, if implemented as part of new development and redevelopment throughout the urban terrain. A comprehensive master plan for a particular watershed would include these options as best management practices and developmental standards.

Okay, now that Owen and others have shown us some ways to augment groundwater resources, and assuming that if these methods are adopted as developmental standards, how do we go about fixing the other very serious problems in our watersheds? What can be done about those streams that have been placed underground in conduit? Sadly, for the most part nothing can be done. The expense of buying up land to restore streams that have been buried makes this a difficult part of the recovery process, particularly as real estate and housing costs continue to escalate. However, opportunities to "daylight" sections of the storm drain system do occasionally present themselves. In other parts of California, and in other states, there are examples of storm drain daylighting that have produced some very nice results. Daylighting of storm drains has brought about benefits that are recognized as assets to communities such as Berkeley and Seattle and other cities.

Here in this region, there is also potential for daylighting of storm drain segments. Analysis of each watershed should be undertaken by the local water resource agency in order to determine the appropriateness of daylighting, and to focus a study on where such measures might be taken. Understanding the structure of the aquatic system that pre-existed the urban buildup is an important key to approaching the question of if and where daylighting might be of significant benefit. Potential may exist in lowlying areas where fill was used to drain a marshy area in order to extend infrastructure or to create land for other uses. Other potentials may exist at the convergence of small drainages, where two or three smaller storm drains come together to empty into larger conduit. Sometimes these topographical features are now used as parks, golf courses, airports, or other open space, since typically these sites present difficulties in building foundations and structures. Necessary to implementing a daylighting solution is availability of some land at the site where a retention basin or a restored segment of the aquatic system may be reintroduced into the landscape. A comprehensive watershed master plan would include taking specific actions such as daylighting of a segment of the storm drain system, where such actions are of benefit to water quality, and to groundwater resources or where daylighting may help to reduce flooding risks.

A possibility for daylighting of a former stream that is now buried and largely forgotten presents itself when large redevelopment projects are proposed for a project site that includes buried conduit within its boundary, and when there is a planning agency that is receptive to making positive change. Study the maps of the area, and try to be aware of developmental proposals as they come under review by the planning agency. This is an advocacy process, and requires timing, patience, and luck.

Where there are streams that remain in the urban setting, there is often hard bank armament, invasive plants that are inappropriate, trash and pollutants, and flooding problems. There is typically an imbalance in sediment transport caused by modifications throughout the watershed that increase runoff and disrupt flow regimes. Stream banks become eroded, and channel dimensions are altered, further reducing the stream’s ability to transport sediments efficiently. Addressing these problems is done through careful analysis of conditions and making corrections over time, through removal of armament, restoration of a natural stream contour, readjusting channel dimensions and stabilization of control points. This work can best be accomplished by the water resource agency that is responsible for maintenance within the channel, as part of systematic and comprehensive watershed planning program. Restoration of the stream buffer within a widened setback is also usually necessary, and can be accomplished as opportunities are presented. When redevelopment is proposed, and where there is a planning agency that is receptive to making positive change, needs can be addressed by asking applicants and investors to repair damaged segments of the stream and the riparian buffer that may lie within the boundary of the project. Restoration needs within a particular watershed should be identified and included as actions to be taken as opportunities and resources allow, and as actions that might be taken by willing property owners. A comprehensive watershed master plan would identify restoration needs, and would target corrective actions to be taken over time.

On the shoreline, where each watershed interacts with the sea within the intertidal zone, there are other problems that have resulted from urbanization. The remnant coastal resources have been greatly diminished in size, and sadly, are seriously depleted biologically. They no longer function as breeding ground and nursery for species that were once abundant. Many of these resources, neglected, maligned, disconnected, and routinely bulldozed and drained as nuisances, have potential to once again become biologically productive links between the fresh water and marine ecosystems. In some cases streams have become disconnected from the coastal lagoon or estuary that they once served. Where possible, reconnections and restoration must be made, so that function can return. Our tidelands will never again extend as vast lagoons and marshes on the coastal plain like they once did. But they can function again, and they must, if we are to be serious about clean water goals, and about living sustainably within the limits of the natural world.

Rehabilitation and restored circulation through remnant coastal systems where possible can and must be addressed through comprehensive watershed master planning of each watershed on the south coast. Reconnection of remnant systems made over time can correct conditions to facilitate restored hydrologic function. Rehabilitation of the coastal resource can be a significant part of cleaning up water pollution, as well as giving important species a place to reproduce in numbers, and returning to them the place where their young can mature before facing predators and risks that await them in the open ocean. A model for reconnection and restoration of the coastal resource can be seen at Ash Avenue in Carpinteria. This outstanding project that returned life to a highly degraded wetland system came about through the efforts of the local authority on restoration of aquatic systems, Wayne Ferren. Similar salvage of intertidal systems may be possible at the mouths of other streams on the south coast, where there is desire on the part of residents to make positive change happen.

The concepts expressed here are all parts of a systematic watershed approach to achieving environmental sustainability throughout the region. Prior to the arrival of Europeans in large numbers, life flourished here. There was great diversity of species, and great abundance. Aquatic Life flourished because water moved across the land and within the land in a specific way that each species could depend on, as the behavior of species was shaped by evolution. For large numbers of humans to continue to occupy this land, our wasteful practices cannot continue. We must begin to carefully manage every drop of water that falls from the sky. Our success here depends on our ability to begin to plan our watershed activities in a way that conforms to the natural design and structure of the land. That process is facilitated through the systematic watershed planning approach that is a common thread through the paragraphs above.

Our success also depends on people such as Owen and Melanie to pioneer new ideas, and on people like Wayne Ferren to demonstrate that positive change can come about. And on people like Margie to distribute information and connect people who are in search of solutions with ideas and with each other.

"You are a visitor here, and you are welcome.
Come to understand this land.
You will no longer be a stranger
when you have learned to live within its natural laws.
And when the land has healed, you will belong."