Proceedings - Teaching and Learning Centre - Simon Fraser ...

Fraser River Action Plan 3rd Research Workshop
Nitrogen and Phosphorus in the Upper Fraser River
in Relation to Point- and Diffuse-Source Loadings
P.A. Chambers and T.D. French
National Hydrology Research Institute
Water quality studies on the Fraser River have focused largely on contaminants and their effect on fisheries and
primary production, particularly in the reach between the town of Hope and the estuary. By comparison, few
studies have addressed water quality issues in the upper reaches of the Fraser River. The objective of this study
was to evaluate trends in nitrogen (N) and phosphorus (P) chemistry in the Fraser River from the headwaters to
Hope. Anthropogenic nutrient loading to the Fraser River upstream of Hope was found to be highly regionalized
with loading being minimal to the reach extending from the headwaters to Hansard, greatest between Hansard
and Marguerite (16x10 4 m 3 /d from indirect pulp mill discharge; 1x10 4 m 3 /d from direct and 2.5x10 4 m 3 /d from
indirect sewage discharge).
Total P export increased from an average of 7 tonnes/yr near the headwaters (Red Pass) to 10,337 tonnes/yr at
Hope, with 85% of the TP export at Hope occurring during the high flow season and only 15% during low flows.
N export also increased from an average of 113 tonnes/yr near the headwaters to 13,217 tonnes/yr at Hope.
Anthropogenic sources contributed 13% (11% from pulp mills and 2% from municipalities) and 5% (4% from
pulp mills and 1% from municipalities) of the total P load at Marguerite during low and high flow seasons,
respectively. The anthropogenic contribution to total P export at Hope was 12% and 3% over the same flow
regime, whereas anthropogenic contributions were negligible upstream of Prince George.
Conclusions
While anthropogenic sources contribute only a small fraction of the nutrient load in the upper Fraser River (