Principia has digitized 12,799 pages of monthly field forms and monthly depth-to-water (DTW) maps to assist in reconciling discrepancies between the Rio Grande Water Conservation District (RGWCD) and the USGS National Water Information System (USGS) databases. The water-level database for the RGWCD is available at http://www.rgwcd.org/wl/index.htm. A list of the RGWCD wells is available here.
As an example, review the web page for RG01 (381742105571801). The web page consistes of an index map showing the general well location relative to the RGDSS model boundary, a specific well location map, pertinent well information in tabular form, hydrographs at two time scales, and finally a water-level data table. The water-level data table consists of Date, Depth-to-Water, Elevation & Data Source columns. Links in the date columns open the water-level documentation, where available. The documentation consists of scanned versions of the monthly field maps and/or the field data sheet for each measurement depending on availability.
These two types of documentation provide different levels of information. The monthly depth-to-water maps are a compilation of data from actual field measurements and as such are secondary sources. Where these are the only available documentation and differences occur between the RGWCD and USGS databases, the differences are noted but no recommendations are provided. As a specific example, scroll down the RG01 (381742105571801) water-level data table to 12/08/1983. There are two entries on this date: 4.43 from the RGWCD database and 4.93 from the USGS database. Clicking on the date opens the Monthly Field Measurement Map for 12/1983. The measured DTW is shown next to well RG01 (381742105571801) in the northern portion of the map as 4.43. Therefore this record was logged as a discrepancey between the two databases with no recommendation for specific changes to the records for well RG01 (381742105571801).
The field sheets, however, are considered primary documentation and for records where the database differs from the field sheet, changes to the database are recommended. As an example of this scroll down the water-level data table for RG01 (381742105571801) to 06/19/1989. Clicking the link on that date opens the field sheet for that measurement which indicates that the correct value should be 2.67 not 3.67 as listed in the USGS database. The recommended change is shown on the corrections page for RG01 (381742105571801).
During this review process, all identified errors in the RGWD database were corrected based on the approach described above. Early date discrepancies were assumed to be correct in the USGS database and the RGWCD database was updated accordingly.
All of the changes recommended at this time are listed in the specific well corrections pages linked from the bottom of this page. As additional information becomes available, additional changes may be required.
Several of the changes recommended for the USGS database are a bit subjective as demonstrated by this example. At well RG08 (380128105484401) on 2/13/1996 the USGS database has a depth-to-water of 3.38 ft and the RGWCD has a depth-to-water of 3.39. A review of the field sheet indicates that both values were actually measured but the field personnel selected the second measurement. I have defaulted to the selected measurement in each case while the value entered in the USGS database varies when there are multiple measurements. The difference is not significant in many of the cases (typically 0.01 ft as in the above case); however, it would be prudent to agree on which values should be used in these cases.