Sediment Lead Loads in the Niagara River, 1986–1992

The problem of estimating sediment lead loads from Lake Erie to the Niagara River and from the river to Lake Ontario is considered. Using weekly data for the period 8 May 1986 to 12 October 1992, autoregressive time series models containing terms for trend and seasonality were developed for the average daily load at the head (FE) and mouth (NOTL) of the river, as well as for the load ratio and difference between the two sites. The estimated average load at the Fort Erie station decreased dramatically from 230 kg/day in 1986 to a roughly constant level of approximately 87 kg/day thereafter, the lowest value of 74 kg/day being reached in 1992. At the Niagara-on-the-Lake station, daily load declined gradually throughout the measurement period, from 110 kg/day in 1986 to 65 kg/day in 1992. Thus, by 1992, there was little difference (9 kg/day) in the loads at the two sites, suggesting that the major contribution of sediment lead to the Niagara River was from Lake Erie.