A Comprehensive Assessment of the Magaguadavic River Watershed’
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‘A Comprehensive Assessment of the Magaguadavic River Watershed’ New Brunswick Wildlife Trust Fund Report (file No.B300-024) By Tim Kelly, Aquatic Scientist Intern Introduction: Considering its application for personal, commercial, industrial and agricultural purposes, freshwater is one of New Brunswick’s most important resources. Recent flooding in December of 2010 resulted in the loss and destruction of many homes along the banks of the Magaguadavic River, and served as a reminder of the eminence of our local watershed and of the need to ensure anthropogenic activities do not detract from its natural capacity to provide a plethora of public goods and services, including the mitigation of such flood events. Generous funding support from the New Brunswick Wildlife Trust Fund (NBWTF) as well as other supporting grants, enabled Eastern Charlotte Waterways Inc. (ECW) to undertake this project in order to conduct a comprehensive assessment of the overall condition of the Magaguadavic Watershed, and to identify risks that should be addressed through future study and/or remediation in order to ensure the continued provision of valuable watershed services into the future. The Magaguadavic River is the second largest source of fresh water to Passamaquoddy Bay, next to the St. Croix River in Southwest New Brunswick (see appendix A for watershed map). “The Magaguadavic watershed covers a land area of 1806 km2 (181, 681 ha)” where a vast sequence of river, lakes, streams, with deep pools, and large riffled sections hold great ecological importance and recreational potential (1). While most project objectives have been met, others are still in progress due to an extension of the project timeline until March 31st, 2011, which corresponds with the termination of an internship for the Project Lead, whose participation was facilitated in October of 2010 by support from the Science Horizons program of Environment Canada. A more comprehensive project report will be produced at this time, which will also be made available to the NBWTF. Completed objectives include a visual riparian zone assessment including documentation of physical and chemical impediments to fish passage and habitation, the collection of benthic macro-invertebrate samples in conjunction with the New Brunswick Department of Environment to further the water classification effort, as well as strategic water quality sampling along the river to produce more current data which can be compared to baseline data collected in the 1990’s, to assess water quality of each section of the river, and in turn to locate isolated pollution sources. The data collected during these exercises as well as information acquired from stakeholders is still subject to analysis, however some preliminary results have been produced and are included here, as well as some recommendations for future study and monitoring efforts. Project Methodology: In keeping with our timeline described in the project proposal, the fieldwork was completed throughout July, August, and October of 2010. In between outings, planning days were needed for referencing maps from the various sections of river, for data entry and analysis of previously collected data, as well as assisting the New Brunswick Department of the Environment with a macro-invertebrate benthic sampling event. Permits were not required for any of these activities. Using a Global Positioning System (GPS) handheld device and a canoe, project staff from ECW traversed the entire 88.6km length of the Magaguadavic River to perform the physical river catchment survey using the environmental stream survey form available on the New Brunswick Aquatic Data Warehouse website (2). Every 500 metres from each previous point was marked for GPS coordinates and a YSI water quality meter (85/50 model) was used to gather water quality parameters at each site. Some portions of the river however were not accessible via canoe due to the presence of high risk rapids. These river reaches were instead accessed by foot, following the same procedures outlined above. A total of 164 river reaches and 17 tributaries, were assessed visually and measured for their dissolved oxygen, temperature, conductivity, and pH levels (Appendix C). The outcomes of the visual assessment were analyzed according to land cover categories, wildlife sightings, and incidence of erosion along the banks. Additional field work included the monthly collection of water quality samples for detailed analysis at ten sample sites representative of different regions of the river during the field season from June to September, 2010. With assistance from the New Brunswick Department of Environment, these sites were designated to correspond with those used for baseline studies performed in the 1990’s to enable comparisons of the physical, chemical, and bacteriological data. Selected data from these sampling events is included in Appendix D, while the procedure employed for their collection is found in Appendix D. ECW also partnered with the New Brunswick Department of Environment to collect benthic macro-invertebrate samples, which will be analyzed at the Canadian River’s Institute to complement previous benthic data in order to further the water classification effort for the Magaguadavic River. To encourage stakeholder participation in the project, letters were distributed to over 300 riverfront property owners to share information pertaining to the project details, while a secondary objective was the acquisition of information regarding concerns and observations with respect to the river, which were encouraged through the inclusion of a question and answer form. This letter is included in Appendix B and recognizes the contribution of the NBWTF and other project supporters. An informal questionnaire was also prepared to elicit information and encourage interest from landowners encountered during field work. Results: Water quality in the Magaguadavic River appears to be in large part unaltered from the baseline studies performed in the late 1990’s. This was expected as there have not been any significant developments along the watershed since that time. While the majority of pH values are typical of healthy aquatic ecosystems, three alarming values documented near the headwaters of the river indicate that future study should be directed at this section of river immediately below Thomaston Corner. In past studies, Piskahegan Stream demonstrated poor water quality. However, the data in this survey importantly indicated that the water quality in the stream appears to have improved, likely due to cessation of mining activity at the Mount Pleasant Mine. Given the high likelihood of a resumption of mining activity in the near future, acquisition of this current data will importantly enable monitoring of the effects of mine tailings on the health of the Magaguadavic River. Dates and locations of select data collected by ECW staff, and analyzed by the provincial are listed in Appendix F. The visual land use assessment revealed that over 90 percent of the river is enclosed by a natural, mixed forest habitat. Also included in this category are beaver ponds and wetlands located adjacent to the shoreline. The next dominant land use apparent along the river banks are occasional clearings for residential settlements, which became the dominant landscape along lower 30km portion of the river. Many of these dwellings were older, suggesting they were likely built before the implementation of legislation mandating the use of riparian zones on waterfront property. The “Other” sections that were sighted were primarily blueberry and/or cranberry agricultural sections located along the river’s edge, indicative of the potential for leaching of agro-chemicals into the river, the detection of which is unfortunately beyond the scope of this project, but which should be highlighted as an issue requiring future study. Figure 1: Land usage breakdown along the Magaguadavic riverbanks. Erosion was visible along the entire stretch of the river, though areas were documented and rated. Along the watershed, the land in most need of immediate remediation were the occasional cut banks on a river meander where the natural low gradient flow of the Magaguadavic was eroding the upstream shoreline of meanders, causing an increase of deadfall of trees to fall into the river. Possible drastic spring flooding could cause serious log jamming and flow interruptions. This could give rise to future project goals directed at remediating these erosion- prone areas to avoid natural damming of the river. Conclusion: Overall, the health of the river appears to be in either excellent or good condition with respect to water quality. The few cleared sections show little to no evidence of siltation runoff. Future settlement to the river shoreline should avoid the tendency to expose large tracts of bare soil to prevent erosion and siltation which compromises water quality. Simple steps in land development can prevent this, such as silt fencing, or the establishment of an untouched 25 metre buffer zone set back from the river’s edge. It is vital to keep this land area preserved as is, and to keep adjacent industry and populations from contributing to the deterioration of water quality, which is best achieved through raising the education and awareness of all stakeholders. The timing of this project gives great insight and background data for the watershed prior to the devastating flooding along the Magaguadavic River that took place in December of 2010. We are now better positioned to evaluate the impacts of such an extreme event, having documented the prior conditions. Furthermore, stakeholders of the Magaguadavic watershed are likely to be more receptive to discussions and efforts to monitor and maintain the health of the ecosystem, having been sharply reminded of the important role and influence of our local watershed. Although analysis of the data is ongoing, selected areas of the river have been identified as required future study, particularly those impacted by industrial activity which include the portions of the Magaguadavic closest to the new Highway 4 overpass construction, the juncture of where the river meets the Canal from Lake Utopia, as well as Piskahegan Stream.