| Abstract/Description or Keywords |
To support the Elk Valley Water Quality Plan (the Plan), a water quality model was developed using GoldSim, that estimates concentrations of water quality constituents of interest at locations in the Elk Valley. Monthly historical flow datasets at locations in the Elk River, the Fording River and local tributaries with mining disturbance were required to support the calibration and validation of the water quality model. Future flow scenarios were used to support the initial evaluation of how conditions may change in the future as a result of mining in the Elk Valley. The majority of tributary watersheds in the Elk Valley are ungauged or have limited monitoring data that are representative of total watershed flows. Good-quality regional flow data are available, however, from active and discontinued Environment Canada stations. The required flow datasets were therefore derived using a combination of methods, depending on location, availability and suitability of observed flow data. Hydrologic analyses involved the simulation of historical and future flows for tributaries directly affected by historical mining activities, or that may be affected by future mining activities, and for the regional watercourses identified by Ministerial Order No. M113 issued by the BC Minister of Environment to Teck. An empirical approach was used to derive monthly flows for ungauged watersheds, given the hydrologic regime (i.e., seasonal runoff is typically snow-dominated) and the amount/type of available data. Four different flow series were identified as representative of natural areas (derived from two representative watersheds: LCO Dry Creek and Hosmer Creek). One flow series was selected to represent mining land types (Cataract Creek). The Fording River and Michel Creek were defined in detail (i.e., at the sub-watershed level) using the flow model. This detailed definition was prepared because of the existing and potential future mining operations and potential mitigation opportunities, and thus the potential for changes in hydrology and water quality at the local (sub-watershed) scale. Flows at the mouths of Fording River and Michel Creek are gauged and the data was used for model calibration and verification of simulated flows. Flows along Elk River and Line Creek, as well as inflows to Lake Koocanusa, are gauged and can be characterized by existing flow records, pro-rated flow records (based on watershed area), or a combination of modelled tributary flows and observed records. Following derivation of flows and statistics for historical conditions, a future flow simulation was conducted. Methods were similar to the historical flow simulation method; however, representative hydrographs were based on statistical flow scenarios rather than a time series of monthly average flows over a historical period. GoldSim was also used to build a flow model to simulate three future scenarios for each watershed: mean monthly flow; high monthly average flow, based on 1-in-10-year high-flow statistics; and low monthly average flow, based on 1-in-10 year low-flow statistics. All flow statistics were generated using data from 1995 to 2010. Statistics were developed for calendar months, with each month developed independently. |
