| Urban Runoff (Part 2 of 2) | Close Window |
| by Eddie Harris | |
| “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.” The concepts expressed below 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 manage carefully every drop of water that falls from the sky, both for our own benefit and that of other creatures who make use of this land. Our success here depends on our ability to plan our watershed activities in a way that conforms to the natural design and structure of the land. The first part of this article in the January/ February edition talked about how recharge of groundwater, a natural function lost within urbanized areas, may be recovered over time. Owen Dell, Melanie Yanke, and others have shown us ways to augment groundwater resources. Assuming that these methods are adopted as developmental standards, how do we go about fixing the other very serious problems in our watersheds? This second part provides some insights. What can be done about those streams that have been placed underground in conduit? Sadly, for the most part, very little 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 demands 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. 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 determine where such measures might be taken. Understanding the structure of the aquatic system that existed before the urban buildup is an important key to approaching the question of if and where daylighting might be of significant benefit. Potential may exist 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 laying foundations and building 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 might include daylighting of a segment of the storm drain system, where such actions are of benefit to water quality, or to augment groundwater resources or where daylighting may help to reduce flooding risks. Where there are surface streams that remain in the urban setting, there is often hard bank armament, invasive plants that deplete habitat, flooding problems, and trash and pollutants. Stream banks become eroded, and channel dimensions are altered, further reducing the stream’s ability to transport sediments efficiently. Careful analysis of conditions and corrections over time, through removal of armament, restoration of a natural stream contour, readjusting channel dimensions and stabilization of control points can best be accomplished by the water resource agency that is responsible for maintenance within the channel, as part of a systematic and comprehensive watershed planning program. When redevelopment is proposed, and where there is a planning agency that is receptive to making positive change, needs can be addressed by asking property owners, applicants and investors to repair damaged segments of the stream and the riparian buffer that may lie within the boundary of their project. 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. 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 marsh that they once served. Where possible, reconnection and restoration must be made, so that function can return. Our tidelands will never again extend as vast estuaries and marshes on the coastal plain as they once did. But they can function again, and they must, if we are to attain clean water goals, and if we are to live sustainably within this region. Rehabilitation and restored circulation through remnant coastal systems where possible may be accomplished through systematic watershed master planning. 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. |
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| Eddie Harris of SBUCC can be reached at eharris@silcom.com or go to http://www.sb-urbancreeks.org/. | |