Forest Investment Account

Abstract of FIA Project 4030001

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Stream crossing quality index (SCQI) survey for 8 sub-basins of tree farm license #30 Prince George Forest District

Author(s): Beaudry, Pierre G.; Floyd, Bill; L’Hirondelle, Becky; P. Beaudry and Associates Ltd.
Imprint: Prince George, B.C. : Canadian Forest Products Ltd., 2003
Subject: Forest Investment Account (FIA), Stream Conservation, British Columbia
Series: Forest Investment Account (FIA) - Land Base Investment Program - Innovative

Abstract

One of the requirements of the Canadian Standards Association (CSA) forest certification programme is that the licensee must maintain water quality within the Defined Forest Area (DFA). The programme requires that the licensee develop an objective measure to document how well water quality is being protected. It is also required that a target be set relative to the measure so that performance can be evaluated. To meet this requirement for TFL #30, Canadian Forest Products Ltd. (CanFor) has developed an index of water quality that focuses on the evaluation of erosion and sediment delivery at steam crossings. This index has been termed the Stream Crossing Quality Index (SCQI). The value of the index is obtained by surveying all of the stream crossings within a given watershed and qualitatively assessing the potential for erosion and the delivery of sediment to the stream at each crossing. The SCQI method focuses on evaluating the addition of fine sediment to streams at stream crossing locations. SCQI scores for individual crossings (referred to as 'individual crossing scores') range between 0 and 1, depending on the potential impact the crossing is having on water quality. A score of 1 indicates that the crossing has the potential for a substantial negative impact on water quality. As the impact is reduced, the score decreases until it eventually reaches 0. The SCQI for the watershed is calculated by adding the individual crossing scores and dividing this value by the watershed area. The resulting overall watershed SCQI score provides an index of the impact that the crossings are having on the introduction of sediments to the stream network at a watershed level. This score can then be translated into a Cumulative Watershed Effects Hazard Rating based on surface erosion and delivery potential, ranging from very low to very high. The SCQI is a refinement of the stream crossing density index (SCDI), an office based exercise that has traditionally been used to determine the impact that stream crossings have on water quality within a watershed. During the 2002 field season eight sub-basins were chosen for sampling in CanFor's TFL #30 which is located in the Prince George Forest District. All of the sub-basin SCQI values were found to be substantially less than their corresponding stream crossing density index values. In the majority of sub-basins, this resulted in a reduction of the road related sediment source hazard rating from very high to moderate. For most of the sub-basins, the hazard ratings were more a function of the high density of stream crossings within the watershed, rather then the poor quality of individual stream crossings. Intensive forest harvesting within TFL #30 has resulted in high stream crossing densities within many of the sub-basins. These high densities increase the importance of using effective erosion and sediment control measures at stream crossings to reduce the potential for downstream negative impacts. The individual crossings scores are a valuable tool in identifying areas of concern for local water quality. Water Quality Concern Ratings (WQCR) of None, Low, Medium, or High were assigned to each crossing based on their individual crossing scores. The majority of the crossings that we surveyed in 2002 within TFL #30 had WQCRs of low or none. Only 7.42% of the crossings received WQCRs of high (Table 1). Most of these crossings were associated with very small streams, i.e. less than 1.5 meters in width. Even though very few crossings surveyed in 2002 had high WQCRs, some common problems were identified throughout the TFL. These include: 1) long ditchlines with exposed soil connected directly to streams, 2) sediment from the road surface directly entering streams at crossings 3) poorly deactivated crossings. Most of the problems were associated with new roads, either recently constructed or recently deactivated, that had poorly implemented Erosion and Sediment Control (ESC) measures or none at all.
Pierre G. Beaudry, Bill C. Floyd, Becky L’Hirondelle,


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Updated August 02, 2006 

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