Given the location of the intake, there are potential water quality issues and saline water migrating upstream. They define their allowable withdrawals based on the combined streamflow of three gauges: the Peace River and two of its tributaries.
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USGS Streamflow gauges on the Peace River.
The two graphs below represent streamflow in 2012. The red line represents the minimum withdrawal of 130 million gallons per day. Streamflow in the Peace is variable, and that’s visible in this graph.
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Water flow in 2012 in the Peace River.
Salinity is also monitored at multiple locations along the river.
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Salinity recording stations along the Peace River.
The next figure represents conductivity at three locations. Note that conductivity mimics flow. Salinity increases during low flow, increasing conductivity and vice versa. The green area represents drinking water standards: when the conductivity is above the green area, the water requires treatment. At higher conductivity levels, desalination is necessary in order to meet the drinking water standard. Since we’re not outfitted for desalination, we don’t withdraw water during those time periods. Instead, we draw on the Aquifer Storage and Recovery systems.
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Bottom conductivity in the Peace River in 2012.
In terms of sea-level rise, there are several different scenarios. For this work, five scenarios were selected and models developed to project a range of possible flow-dependent salinity relationships for the future.
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Projected potential probabilities in sea-level rise.
The figure below takes the five scenarios shown in Figure and depicts the relationship between total dissolved solids and streamflow. The water use permit doesn’t allow diversion when flow is less than 130 CFS.
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The five scenarios relating streamflow (CFS) and water quality (TDS).