The Minnesota County Well Index

Database Dictionary

The Minnesota County Well Index Database

Overview

The County Well Index (CWI) geodatabase developed by the Minnesota Geological Survey (MGS) and is maintained in cooperation with the Minnesota Department of Health (MDH). CWI contains basic information for over 557,000 water-wells, and borings drilled in Minnesota. The data is derived from water-well contractors' logs of geologic materials encountered during drilling. Confirmed locations and geologic well records are available for over 380,000 of the wells. Available data also includes casing, screen and pump information.

The relational database management system (RDBMS) used for storing the data is Oracle

Spatial

Coordinate System
The well location coordinates (x,y) are stored in Oracle using ESRI Spatial Database Engine (SDE). The spatial data coordinate system is Universal Transverse Mercator (UTM), Zone 15, NAD83, and units in meters.

Well Locations
Well locations (x,y) are input after a well has been field verified. This involves the following steps:

Determine the approximate location from any locational information provided with the data - name, address, PLS (Township, Range, Section and Quarter Sections).
Find the actual well.
Verify that the well found is the well referenced in the log or data (The unique number is the correct unique number) by the well tag on the well, by asking the owner or a neighbor, if possible, about the well's construction date, the depth, the driller, the well use, and the owner's name and address.
GPS the well and/or plot the actual location on a topographic quadrangle map.

Without an accurate location, a well record and the associated quality and condition data we have worked so hard to correlate are of little value. It is not possible to describe or map the geology and ground-water conditions of an area unless the data are located geographically. Furthermore, the accuracy of the "picture" or interpretation of the ground-water conditions and environment relies directly upon the accuracy of the locations of the data.

Minnesota Unique Well and Boring Number System

The Minnesota Geological Survey developed the unique number system for wells and other subsurface drill hole features in the 1970's to establish a standardized means for referencing data to them. The unique number assigned to each well or drill hole represents the official state identifier. Once assigned, the number is never used again; it is "unique" to that well or drill hole. Minnesota Unique well or Boring numbers are automatically assigned when the driller fills out the Minnesota Department of Health's Well and Boring Record on which the number is pre-printed. Wells drilled prior to the development of the well code in 1974 were not originally assigned numbers. These records, originally kept in driller's files and assorted county and state agency collections, are loosely referred to as the "historic logs". These records were assigned unique numbers by the Minnesota Geological Survey. The table below indicates how Minnesota Unique Numbers have been assigned.

MN Unique Numbers			Description
1	-	9,999	Minnesota Department of Transportation (MNDOT) Soil Borings
10,000	-	19,999	Water Wells
20,000	-	49,999	Mining Companies Exploration Borings
50,000	-	99,999	Minnesota Department of Transportation Exploration Borings
100,000	-	199,999	MDH Well Management Well and Boring Records (printed)
200,000	-	258,000	Historical Well Records
258,001	-	270,000	MDH – Public Water Supplies and historical well records
270,001	-	299,999	Historical Well records
300,000	-	399,999	Historical mining exploration borings & current unsuccessful boreholes
400,000	-	875,000	MDH Well Management Well and Boring Records (printed)

1B Unique Numbers (AKA W-Series Unique Numbers)
If no log exists for a well, it is not assigned a standard 6-digit unique number. Instead, it is assigned what is referred to as a “1B” number, a series number starting at 1,000,020,001. This number replaces the “W-Series” number formerly used in CWI to reference records with no down-hole log. Wells with old W-Series numbers have had 1B numbers below 1,000,020,000 assigned but the W-Series numbers have been preserved in the alternate id table so they can be seen when viewing CWI records and when referencing the log to maps or documents that use the original W-Series number. To reference the new number in written reports, the number is referred to as “1B-xxxxx”, where xxxxx is replaced with the last six digits of the number. MGS coordinates assignment of 1B numbers to minimize the possibility of numbers being assigned more than once, or two different 1B numbers being assigned to the same well. Upon request, and after receiving proper location documentation, the MGS will provide 1B numbers for wells to county staff, well drillers, agency staff, or others involved in county ground-water data collection.

Scanned Construction Logs

Although not all construction logs are available in a electronic format, there are currently two sources for obtaining a scanned image for a construction log.

Minnesota Department of Health - http://apps.health.state.mn.us:12000/pdf/all/WN/00517750 Click on link or copy and paste into browser. Replace 517750 with your unique number.

Minnesota Geological Survey - http://mgsweb2.mngs.umn.edu/welllogs/190471.pdf Click on link or copy and paste into browser. Replace 190471 with your unique number.

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