ABSTRACT: Development of environmental performance standards for stream sediments in agricultural regions of Atlantic Canada.

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Within the Water Theme of the National Agri-Environmental Standards Initiative (NAESI), sediments have been identified as a primary stressor for which standards are needed. Elevated sediment loads in streams can impair ecological functions and alter the structure of aquatic communities. Potato (Solanum tuberosum L.) production regions of Atlantic Canada are particularly prone to soil erosion due to rolling topography, high intensity rainstorm events and conventional tillage practices. To assess the influence of watershed heterogeneity and agricultural practices on total suspended solids (TSS) in streams and to develop performance standards for sediments, field sampling programs were established in northwestern New Brunswick (NB) and in central Prince Edward Island (PEI). Watershed sizes ranged from 12–30 km2 in NB and 5–25 km2 in PEI. TSS was measured at fixed weekly and monthly time intervals and, where available, according to episodic rainfall/discharge events. GIS was used to quantify agricultural intensity within watersheds as coarse land cover (% agriculture), extent of forest cover and riparian zones, and (beneficial management practice) BMP implementation rates. Results to date indicate that background (i.e. “normal” flow periods) TSS is positively related to agricultural coverage (range: 5–95% in NB and o50–95% in PEI). In PEI, differences in BMP implementation rates help t explain some of the variation in TSS among watersheds. As fine soil particles and sediments can function as substrate for agriculturally-derived nutrients, pathogens and pesticides, trends observed for TSS are likely to be correlated with other agrienvironmental stressors at watershed scales.

Bibliography of Canadian Geomorphology