This data release contains water chemistry data used to create a total dissolved solids (TDS) map of the Paskapoo hydrostratigraphic unit (HSU). The data were acquired from the following public sources:
1. the Alberta Government's Alberta Water Well Information Database (AWWID)
2. a previous Alberta Geological Survey water sampling project reported in AGS Special Report 81
Data have been processed, relevant records selected, and outliers removed to compile this dataset.
The potential for up to approximately 566 m (sometimes approximately 1131 m) of horizontal accuracy error for water wells may also introduce errors in the surface elevation, which is derived from the provincial 25 m DEM, based on the location of the well. This error is likely on the order of plus/minus 5 m, but may be 10s of metres in areas where there are large changes in elevation. Any error in elevation may influence the allocation of the well as well as sampling location. These sources of error are not unique to this study and are encountered in any hydrogeological study that uses the AWWID, unless further refinement of well locations is undertaken.
The mid-point of the sampled interval is a calculated value and its accuracy is dependent on the accuracy of the measured depths and elevations provided in the well header. These values are somewhat inconsistent for the water wells because many of them are not surveyed.
Process steps for selection of chemical analysis from water wells:
1. Water well records with completion interval and/or total depth information, and complete chemical analysis, were selected;
2. Chemical analyses from completion intervals longer than 15 m were excluded;
3. Chemical analyses were allocated to the Paskapoo HSU based on the completion interval, or the total depth of the well if completion interval was not available;
4. Chemical analyses from wells with completion intervals straddling the bottom of the Paskapoo HSU were excluded, unless they were from wells in data-poor areas and it was verified that less than 30% of the completion interval extended into the formation directly above or below the HSU, but not into any other formation;
5. The acceptable charge balance error was constrained to ±10%;
6. Chemical analyses which reported CO3 and pH <8.3 were excluded;
7. The concentration of total dissolved solids (TDS) was determined either by summing the concentration of major constituents (if available), or by using the TDS values as reported in the source dataset (if major constituents were not available);
8. Outliers were manually removed during the mapping process based on substantial difference in screen depth, and unexplained anomalous values.
Process steps for selection of formation water analyses from compiled sources:
1. Any records where the sampled interval was identified as the Paskapoo HSU were included in the initial dataset.
The final dataset includes only those records that were used in the production of the final TDS surface.
Details about the screening process can be found in the following reference: Jensen, G.K.S., Rostron, B., Palombi, D. and Melnik, A. (2013): Saskatchewan Phanerozoic Fluids and Petroleum Systems project: hydrogeological mapping framework; in Summary of investigations 2013, Volume 1, Saskatchewan Geological Survey, Sask. Ministry of the Economy, Misc. Rep. 2013-4.1, Paper A5, 10 p. URL http://publications.gov.sk.ca/details.cfm?p=80100 [October 2014].