Cumulative effects take on a different meaning in Southern California. Typically, watersheds are affected by disturbances that are long term and with little or no recovery to follow. These effects are the results of urban interface development and the ever-increasing demand that our special interest publics place on these unique wildland and forested areas.

It has become commonplace that disturbance threshold values are approached or exceeded on our watersheds under existing conditions and that all development alternatives double or triple the existing disturbance value.

Most of these effects are occurring on the private lands within the watersheds. In the private sector, environmental and engineering firms reverently believe that all effects can be mitigated to nonsignificance. If not you just pour more concrete.

When doing the accounting of the magnitude of effects in a watershed, a full understanding of the conditions cannot be had by converting all disturbances to ERAs. Instead it is better to evaluate each type of disturbance by itself and then apply a factor to that impact. A clearer picture can be drawn by accounting for roads by surface types, roofs, decks, driveways, parking lots, utility corridors, hiking trails, OHV trails, grazing allotments, organizational camps, ski areas, and other types of disturbances.

We have created disturbance classes that are compared with land risk classes in matrix table. This makes a useful graphic for what types of disturbance are occurring on which land risk units.

The actual bottom line however is not the health of a watershed, nor what value was obtained for a threshold analysis, but what mitigation can be done to have a "go" project. The pervasive attitude is still what I heard sixteen years ago by a line officer at a watershed conference, "Don't tell me I can't get the logs out of the forest, tell me HOW to get the logs out of the forest." This put a lot of faith in BMP implementation. It is real easy to list the BMPs for project approval, but in Southern California actual implementation and documentation of accomplishment is rare.

My fear is that "Cumulative Effects" has become such a common phrase and is so ill defined in most people's mind, that it is for most purposes meaningless. Yet, it is tossed around by even the most unlikely groups.

Maybe in the tossing, it will find an open window and we can get on with real resource conservation using terms we can all understand.

Dennis may be reached at (714) 383-5588