Forsite Consultants Ltd. recently completed a fish passage assessment project within the Lillooet TSA focusing on high value fisheries watersheds. These watersheds have been identified through an assessment process conducted by the provincial government which used a combination of biodiversity and socioeconomic variables to assign priority rankings to watersheds on a provincial scale. Within the Lillooet TSA, the Tyaughton, Gun, Cadwallader, and Hurley River watersheds were all identified as high priority for fish passage assessments. The intention of this work was also to assess culvert located within these watersheds that may be acting as barriers to fish passage. These culverst are located on non-status, Forest Service, and pre- 1995 built roads.
In total, we completed 45 detailed assessments on culverted sites which were deemed to have fisheries value. We also made several hundred other determinations of non-fish bearing on other structures within these watersheds- each of these sites was field verified. Upon completion of field data collection, we completed a cost-benefit analysis for each of these structures which took in to account the cost to replace the structure as well as the amount of habitat that would be gained should fish passage be restored. The results of this process show that two sites are a priority for replacement - TY639 and TY 603- both of which are blocking access to greater than 5 km of upstream habitat.