1. Introduction
Studies have shown that land cover and land use in a watershed impact both the quantity and quality of water in streams, larger rivers, estuaries and bays (Huang & Klemas, 2012; Baker, 2003). For example, Huang & Klemas (2012) found that less erosion occurs on land use with dense vegetation cover than on bare soil, and that urban areas discharge rainfall more rapidly due to impervious surfaces. In the same study they also found that some models predict that watersheds with greater than 50% agricultural land use or 20% urban land use have severely degradation water quality.
This study examines the land use impacts on water quality in two watersheds in Langley/Aldergrove and Abbotsford, British Columbia. These watersheds differ in flow regime and input sources. Bertrand Creek, which runs from Aldergrove to the Nooksack River in Washington State, is influenced by urbanization and agriculture runoff. The Canadian portion of its watershed includes just over 50 km2 of land and 18 km of mainstem channel (Pearson, 2004). It is a very flashy system due to compact, clay-rich, glacio-marine soils in large portions of the watershed and some reaches run dry during summer droughts (Pearson 2004). The riparian zones of some reaches are forested while others lack woody vegetation completely. Pepin Creek, the watershed immediately east of Bertrand Creek, also drains into the Nooksack River. It is impacted by gravel mining, but also runs through forested parkland and recently restored riparian areas. The Canadian portion of its watershed includes approximately 21 km2 of land and 6.4 km of channel (Pearson, 2004). It is predominantly groundwater fed from a glacial moraine and maintains a base flow of approximately 200 l/s. The riparian zones of the upper reaches are partially forested but are surrounded by gravel mining and the lower reaches are well forested or vegetated. These watersheds were selected because they are both home to two endangered freshwater fishes, Salish Sucker (Catostomus sp.) and Nooksack Dace (Rhinichthys sp.), and water quality has been identified as a major threat to their recovery (Fisheries and Oceans Canada, 2012). They are also used as spawning and overwintering habitat for Coho (Oncorhynchus kisutch), and resident Cutthroat Trout (Oncorhynchus clarkii).
To test the hypothesis that land uses, such as agriculture and urbanization, have negative impacts on water quality, this study uses a GIS spatial statistical tool to assess Bertrand Creek and Pepin Creek, which are subjected to various land use practices (urban, rural, agriculture, industry and forest).
This study examines the land use impacts on water quality in two watersheds in Langley/Aldergrove and Abbotsford, British Columbia. These watersheds differ in flow regime and input sources. Bertrand Creek, which runs from Aldergrove to the Nooksack River in Washington State, is influenced by urbanization and agriculture runoff. The Canadian portion of its watershed includes just over 50 km2 of land and 18 km of mainstem channel (Pearson, 2004). It is a very flashy system due to compact, clay-rich, glacio-marine soils in large portions of the watershed and some reaches run dry during summer droughts (Pearson 2004). The riparian zones of some reaches are forested while others lack woody vegetation completely. Pepin Creek, the watershed immediately east of Bertrand Creek, also drains into the Nooksack River. It is impacted by gravel mining, but also runs through forested parkland and recently restored riparian areas. The Canadian portion of its watershed includes approximately 21 km2 of land and 6.4 km of channel (Pearson, 2004). It is predominantly groundwater fed from a glacial moraine and maintains a base flow of approximately 200 l/s. The riparian zones of the upper reaches are partially forested but are surrounded by gravel mining and the lower reaches are well forested or vegetated. These watersheds were selected because they are both home to two endangered freshwater fishes, Salish Sucker (Catostomus sp.) and Nooksack Dace (Rhinichthys sp.), and water quality has been identified as a major threat to their recovery (Fisheries and Oceans Canada, 2012). They are also used as spawning and overwintering habitat for Coho (Oncorhynchus kisutch), and resident Cutthroat Trout (Oncorhynchus clarkii).
To test the hypothesis that land uses, such as agriculture and urbanization, have negative impacts on water quality, this study uses a GIS spatial statistical tool to assess Bertrand Creek and Pepin Creek, which are subjected to various land use practices (urban, rural, agriculture, industry and forest).