Articles - THE BLUE-LINE STREAM AND ITS PROGENY

Malibu's Local Coastal Program (LCP), consisting of a Local Implementation Plan (LIP) and a Land Use Plan (LUP), was adopted September 13, 2002. Until then, City planning policy considered the so-called "blue-line stream" as one planning criterion for development. The blue-line streams to which the City then made reference are those appearing on the U.S. Geological Survey 7.5-minute Topanga, Malibu Beach, Point Dume, and Triunfo Pass quadrangles. The blue lines are essentially a cartographic device to used to indicate channels that under uncertain conditions carry flows, in other words, streams, whether perennial, intermittent, or ephemeral. Such a designation probably is based simply on aerial photographs showing channel vegetation, but so far as the USGS is concerned, they have no specific hydrologic or biologic significance. Therefore, the blue-line stream has no rational relationship to recognized planning concerns. Preliminary analysis indicates that there is an average of about 2.5 miles of blue-line streams per square mile in the south slopes of the Santa Monica Mountains in Malibu. Therefore, they were to some extent a significant criterion in City planning during the period of about eleven years before adoption of Malibu's LCP.

With adoption of the LCP, reference to the blue-line stream has been eliminated in favor of, simply, "stream." Lest anyone think this provides a more rational approach to City planning, it is to be noted that the LIP (p. 27) defines a stream as:

"... a topographic feature that at least periodically conveys water through a bed or channel having banks. This includes watercourses having a surface or subsurface flow that supports or has supported riparian vegetation."

"Riparian" is not defined in the LIP, but generally, it refers to a location along a water course. Less commonly, it also refers to a location on a water body such as a pond or a lake, although in that sense, "lacustrine" is a better modifier. Of some concern is the tendency for authorities to regard any riparian vegetation as, by definition, a species worthy of protection, although why anyone would want to protect such vegetation as poison oak or nettles is difficult understand. In any event, considering the phenomena of rill flow and rivulet flow, and the generally widespread chaparral and coastal scrub communities common to Malibu, it seems that the preparers of the LIP should have been a little more definitive. Otherwise, in terms of planning, essentially all of Malibu is one sort of stream or another.

There are two planning criteria especially important with respect to streams in Malibu. One is the fact that unless demonstrated otherwise, at the expense of the applicant of course, all streams are considered to be ESHAs (LIP Ch. 4, Sec. 4.3, B, 6). For the omnivorous effects of the ESHA concept and the difficulties it poses for development in Malibu, a careful reading of the Malibu LCP and especially LIP Chapter 4 is advisable.

The other planning criterion relating to streams that is especially important regarding land development in Malibu is the distance of septic-system elements, i.e., the septic tank, the drain field, and the seepage pit, from a stream, all being 100 feet (LIP Ch. 18, Sec. 18.8, M, p. 303). Why 100 feet? Good question. The closer to a stream a source of degradation, the more likely degradation will occur, but there is nothing magic about 100 feet. As a rational approach, stream channels worthy of protection through some sort of planning policy, need to be defined based on such hydrologic variables as stream order, gradient, bed width, tributary area, ground-water recharge, vegetative species, and hydraulics, and certainly not blue ink.

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