The SCQI survey is based on the concept of the stream crossing density index (SCDI) used in the Watershed Assessment Procedure (WAP) (Government of BC 1999). The assumption in the WAP is that the risk to water quality increases as the density of stream crossings within a watershed increases. The stream crossing density index assumes that every crossing is a problem from the point of view of erosion and sediment delivery. Although this is a useful index to highlight potential for cumulative effects, it does not consider the actual quality of erosion and sediment control (ESC) or effective de-activation measures that may have been implemented at a particular stream crossing. Consequently, the numerical value of such an index will always increase with increasing activity within a watershed. Thus, such an index cannot evaluate progress towards the achievement of a specified goal, this being an explicit requirement of many forest management certification schemes (e.g. CSA). Consequently, it became necessary to develop an index that would document and evaluate problems as well as successes. The index must provide an incentive to improve practices by documenting those practices that achieve the desired goals. The SCQI method was designed to be such an index. The SCQI method is based on the concept that the impact of stream crossings on water quality can be reduced through effective erosion and sediment control practices, and that this can be evaluated and scored. As with the SCDI, each crossing within a watershed is, at priori, assumed to be having a negative impact on water quality. However, the theoretical negative impact of this stream crossing can be reduced if the crossing is evaluated in the field and does not show any signs of erosion and sediment transport to the stream. Using this method of evaluation a crossing that shows substantial problems receives an individual crossing score of one (1). As the quality of a crossing improves, the score is reduced, eventually reaching zero (0). This can effectively eliminate the crossing from the 'erosion and sediment producing' inventory. As the scores for the individual crossings are reduced, so is the SCQI for that watershed. This mechanism provides an incentive to implement good ESC measures. The SCQI method also provides valuable data that can be used to identify specific problem sites or areas. This enables the forest manager to implement proper ESC measures in areas where it is required. By addressing specific problems, the negative impact on water quality will be reduced and the overall SCQI score for that watershed will also be reduced. It also enables forest licensees to focus their resources to areas that will receive the greatest benefits. Specific problem crossings were identified in sub-basins with a high or very high SCQI and a summary of the problems were also provided in the report. In addition, the SCQI method provides a way to monitor progress in regards to water quality. The SCQI values calculated in this report could be used as a baseline to monitor the relative improvement of forest practices within the Moberly Watershed. P. Beaudry and Associates Ltd.
P. Beaudry and Associates Ltd.. 2003. Survey of small and large sediment sources within the Moberly Watershed Dawson Creek Forest District. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2003MR175
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), Stream, Conservation, British, Columbia
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