Stream - Riparian Rapid Assessment

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categories, such as "functional/non-functional", or "yes/no", can be subjective and difficult to repeat in the same way from one year to the next, or when conducted by different observers. In addition, dichotomous scoring systems often are not able to provide sufficient insight into the ecological processes that may be affecting the ability of the system to provide (or not provide) desired functions that would indicate whether active restoration efforts might be necessary. We used a review of existing assessment and monitoring protocols, extensive external peer-review, and our own individual research experiences to create a five point scale for each variable. The maximum score (5 points) is given when that component of the system is fully functional and healthy, and is what would be found in a similar reach that has not been heavily impacted by humans. The miiumum score (1 point) is given when the component is completely non-func- tional, and when it is not capable of providing the desired ecosystem value of that variable.' Reference Reaches Every stream will have its own geologic and watershed characteristics that will necessarily limit both its potential geomorphic form and its ultimate ecological function. For example, streams in narrow bed-rock canyons will never develop the same number of meanders and floodplain width as will similarly sized streams that run through broad alluvial fans. For this reason, we suggest that whenever possible, the stream reach under evaluation should be compared to a ref- erence reach, and the scores given be scaled with respect to that reach. Reference areas should have similar geomorphic, fluvial and biological characteristics to the study reach, and should be as free as possible of current and past human impacts. When this type of reference reach is not available, ratings should be based upon what the observer would expect to see if all physical and ecological processes were occurring without human impact, while allowing for natural dis- turbance processes that may be characteristic of the system. GeogNaphic Application The RSRA protocol presented here was developed specifically in reference to small and medi- um sized stream reaches in the Colorado Plateau and in the adjacent areas of the American Southwest. It applies most directly to low and mid-gradient watercourses, and therefore will be most useful in the lower and middle elevation watersheds of this region. Large streams and rivers, as well as those at high elevations in mountainous regions that have high gradients, are often subject to forces and conditions that are not fully considered here and therefore may not be adequately described by this protocol. However, with only slight modification, the RSRA should be applicable to many other parts of the American West, as well as to other arid and semi-arid regions of the world. The range of scores used in the RSRA method from 1 to ~ is similar to the functional condition judgments used b~ the US Bureau of Land Management and other agencies in their '`Proper Functioning Condition' (PFC) asscss- ment protocol (USDI 1998). In that se stem, streams are rated as ranging from either "not in proper functioning condition," which ~~-•ould be equivalent to mean scores of 1-2 in the RSRA. to "in proper functioning condition," which would be equip-alert to means scores of 4-~ in the RSRA. Intermediate scores in the RSRA protocol (>2 - <4) can be considered to be equivalent to the "functional at rislc~' rating in the PFC protocol. Additional discussion of the similarities and differences bcriveen the RSRA and PFC sure°e~~ protocols is given in Stevens et al. (2000. 7