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Well Location and Percent Dakota Yield
Wells with Water Rights
Water in Kansas may be appropriated for beneficial use subject to vested and existing senior water rights for a variety of uses. Water rights are not required for "domestic" uses such as household purposes, livestock as part of operating a farm (fewer than 1,000 confined head of cattle and less than 15 acre-ft [18,500 m3] of use), or irrigation over less than 2 acres (0.8 ha) (Kansas Department of Agriculture, 2011). Wells with water-right permits are mainly for larger-capacity production for irrigation, industrial, municipal, large feedlots, and other purposes, although a "domestic" well may also file to have the implied domestic water right under Kansas law quantified. The Division of Water Resources (DWR) in the Kansas Department of Agriculture collects and checks data on the location and reported water use for wells with appropriation rights. The DWR stores its water-right data in an Oracle-based relational data-base management system called the Water Rights Information System (WRIS). The Kansas Geological Survey (KGS), in cooperation with the DWR, developed an online interactive website, called the Water Information Management and Analysis System, or WIMAS, to query and analyze WRIS-based data (http://hercules.kgs.ku.edu/geohydro/wimas/index.cfm).
The point of water access and control associated with a water right is known as a point of diversion (PD). Usually only one well is associated with a PD, although some PDs are batteries of two or more wells tied together. The WRIS includes aquifer codes for many PDs that have groundwater rights. Aquifer codes include those for the Dakota Formation, Kiowa Formation, Cheyenne Sandstone, confined or unconfined Dakota aquifer, combinations of the Dakota aquifer with alluvial or Ogallala aquifers, and the Jurassic Morrison Formation, as well as other aquifers. Up to three aquifer codes can be associated with a PD.
The first step in determining the locations of wells partially or solely in the Dakota aquifer was to search and download data for all PDs in WRIS with the aquifer codes listed in table 1. The only Dakota-related codes in table 1 that were actually found were 330-333 and 340-343. Some of the PDs with these codes also included the codes 75 (Ark River [IGUCA]), 100 (Quaternary System), 112 (Tributary alluvium), 113 (Main stem alluvium), 115 (Terrace), 144 (Meade Grand Is Fm), 130 (Illinoisan Stage), 180 (Undifferentiated Kansan/Nebraskan), 200 (Tertiary System), 210 (Ogallala aquifer), 211 (Ogallala Formation, 400 (Jurassic-Triassic systems), 420 (Dockum Group), and 500 (Permian System). The data were subdivided into PDs located within the extent of substantial saturated thickness of the High Plains aquifer (HPA) and those located outside of the extents of the High Plains and alluvial aquifers.
Table 1--Aquifer codes used for points of diversion search of completions in the Dakota aquifer system.
| Aquifer code | Aquifer name |
|---|---|
| 94 | Dakota-Cheyenne |
| 330 | Dakota Aquifer System (unconfined) |
| 331 | Dakota Formation |
| 332 | Kiowa Formation |
| 333 | Cheyenne Sandstone Formation |
| 340 | Dakota Aquifer System (confined) |
| 341 | Dakota Formation |
| 342 | Kiowa Formation |
| 343 | Cheyenne Sandstone Formation |
| 95 | Cheyenne-Jurassic-Triassic |
| 300 | Cretaceous System |
| 92 | Alluvium-Dakota |
| 93 | Ogallala-Dakota |
| 64 | Bedrock |
| 99 | Rock |
The next step involved using the Kansas Master Ground-water Well Inventory (http://hercules.kgs.ku.edu/geohydro/master_well/index.cfm) to determine which of the PDs have well-log records. The KGS had recently developed the system, which indexes the water rights, drillers' logs, and depth-to-water data together. This allows water usage along with water-level changes to be associated with geologic sources when the data records are available. The Kansas Department of Health and Environment (KDHE) has required well drillers to file water well completion records (WWC5 forms) for all types of constructed, reconstructed, and plugged wells since 1975. Lithologic logs are a part of the drillers' records. The KGS stores the drillers' logs and has developed an online interactive data base of the log information (http://www.kgs.ku.edu/Magellan/WaterWell/index.html). The data extracted from WRIS were then subdivided into data sets of PDs with and without WWC5 well logs.
To facilitate examination of the data relative to other information, such as aquifer extents (for the High Plains, alluvial, and Morrison-Dockum aquifers), the data extracted from WRIS were converted into shapefiles using ArcGIS (http://www.esri.com/software/arcgis/index.html) and viewed in ArcGIS Explorer (http://www.esri.com/software/arcgis/explorer/index.html). Additional shapefiles were created from data extracted from WRIS for PDs that are located within the extent of the Dakota aquifer but that have aquifer codes other than those in table 1 and also for PDs that have no aquifer code. As for the PDs with Dakota aquifer codes in WRIS, individual shapefiles were created for PDs with and without WWC5 records.
WWC5 records include well depth. WRIS records for some PDs include reported well depths. Well depths from both sources were used to filter data extracted from WRIS for those PDs with other aquifer codes and without codes that are located within the HPA extent and that had depths greater than 50 ft (15 m) below the depth to the bedrock surface underlying the HPA. Excel spreadsheet files were also created for the different types of data sets for examination of data from WRIS associated with the PDs, such as DWR identification number (the PD number for the same location with multiple PDs with different water rights or for replacement PDs for the same water right), water-right number, water-right identification number, legal location (township, range, section, section qualifiers), and DWR aquifer codes. The initial Excel files included the link to the online WWC5 data base for PDs with well-log records along with well depths, where available. WWC5 links and well depths were added when additional information on well depths and matches between PDs and well logs were found.
A variety of information in WWC5 records for permitted wells was examined to estimate the percentage of the recent yield (during the several years before 2012) for each well determined to be drawing water from the Dakota aquifer. This information included the completed well depth, depths of the screened intervals and of grout seal, the top depth of Dakota units below overlying strata based on the lithologic log, the static water level, water levels after a pumping test, the relative permeabilities and thicknesses of lithologic units acting as aquifer units (e.g., sand, gravel, sandstone), and any other relevant information such as whether Dakota sandstone took water during drilling. For wells located outside the HPA extent, the location relative to the extent of the Dakota aquifer confined by overlying upper Cretaceous strata and the salinity of water in the upper Dakota aquifer were also considered. For wells located within the HPA extent, the bedrock surface depth (from Macfarlane and Wilson, 2006) at the well location was used to assist in interpretation of the lithologic log if the log description did not clearly indicate the HPA-Dakota strata contact. After determination that a well was screened in both the Dakota aquifer and overlying unconsolidated sediment, the approximate depth of the static water level expected during the winters of the several years before 2012 was compared to that for the contact between Dakota and overlying strata. For those wells that were completed before this period, the static water level was estimated based on values for nearby wells with recent WWC5 records or on measurements in the online KGS data base WIZARD (http://www.kgs.ku.edu/Magellan/WaterLevels/index.html). This water level was used to determine the relative thickness of the saturated HPA contributing to the well yield relative to the sandstone thickness of the Dakota aquifer contributing to the yield.
The following subsections describe in more detail the types of files and the information considered for estimating the percent Dakota yield out of the total yield of a well:
1. PDs with DWR Dakota codes within the Dakota aquifer extent
A few locations of PDs with Dakota aquifer codes were found to be outside of the Dakota aquifer extent; these were deleted from the spreadsheet files. WWC5 well-log records for a few PDs indicated that the well had been plugged; these were also deleted from the files.
a. PDs with WWC5 logs
The first information examined in a WWC5 record was the completed well depth, the bottom of the deepest screened interval, and the top depth of Dakota stratigraphic units below overlying strata based on the lithologic log. The location of grout interval(s) was considered to determine whether screened intervals only in the Dakota aquifer were sealed from overlying units. Wells completed entirely in the Dakota aquifer or the Dakota aquifer and some underlying Morrison-Dockum aquifer were assigned 100% yield from the Dakota aquifer.
After determination that a well was completed in both the Dakota aquifer and overlying unconsolidated sediment, the approximate depth of the static water level expected during the winters of the several years prior to 2012 was compared to the Dakota-overlying strata contact. WWC5 forms include the static water level measured at the time of well completion. For those wells that were completed before this period, the static water level was estimated based on values for nearby wells with recent WWC5 records or on measurements in the online KGS data base WIZARD. This water level was used to determine the relative thickness of each aquifer contributing to the well yield. If the water level was at or below the contact of the Dakota aquifer and an overlying unconsolidated aquifer, then the well yield was assigned as 100% Dakota. Substantial declines in water levels in the HPA during the last few decades have caused many older wells that were originally screened in both the HPA and underlying sandstones to decrease in production and produce a substantially smaller fraction of their yield from the HPA and a larger proportion from the Dakota aquifer.
If a well could possibly have a mixture of yield from the Dakota and other aquifers, the lithologic log and other information in the WWC5 record were examined in more detail. This included determining whether the well was screened in both the other aquifer(s) and the Dakota aquifer, was screened only in the other aquifer(s) but completed into the Dakota aquifer with a gravel pack in the annular space around the casing, or screened only in the Dakota aquifer but included a gravel pack around the casing in the other aquifer(s). A greater weight to the percentage of yield from the Dakota aquifer was given for those wells screened rather than only gravel packed in Dakota strata. The depth of grout sealing the annular space of the well within the overlying unconsolidated aquifer was part of the consideration for those wells with gravel pack above the screened interval(s). In some cases where pumping test data existed for a well in a WWC5 record, the pumping rate and the water level at the end of pumping were considered. Larger pumping rates such as above 1,000 gpm and water levels that remained in the overlying aquifer suggested a larger percentage of well yield derived from the overlying aquifer than the Dakota aquifer and vice versa.
The general character of the lithologic log was examined to estimate the percentage of total yield that would probably be produced based on a recent static water level. The hydraulic conductivity of the Dakota aquifer based on 22 field hydraulic tests of supply and observation wells ranges from 3.6 to 88 ft/day (1.1-27 m/day) and has a geometric mean of 12.5 ft/day (3.8 m/day). The hydraulic conductivities of core samples of Dakota sandstone in a site in central Kansas vary greatly, from less than 1 ft/day (0.3 m/day) to more than 100 ft/day (30 m/day); most of the values fall in the range 1-100 ft/day (0.3-30 m/day) (Macfarlane, Doveton, and Whittemore, 1998). Hydraulic conductivities used in a regional model of the Dakota aquifer in the central Midwest ranged from less than 10 ft/day (3 m/day) in westernmost Kansas to about 50 ft/day (15 m/day) for the easternmost portion of the aquifer in Kansas (Helgeson, Leonard, and Wolf, 1993). In comparison, the hydraulic conductivities of sediments in the HPA of southwest Kansas are about 20 ft/day (6 m/day) for fine to medium sand, 100 ft/day (30 m/day) for medium to coarse sand, 200 ft/day (61 m/day) for sand and gravel, and 300 ft/day (91 m/day) for gravel based on a calibrated groundwater flow model that used lithologic descriptions from WWC5 records (Liu et al., 2010). U.S. Geological Survey (USGS) values for HPA sediments are 50-80 ft/day (15-24 m/day) for fine to medium sand, 90 ft/day (27 m/day) for coarse sand, 160 ft/day (49 m/day) for sand and gravel, and 200-350 ft/day (61-107 m/day) for fine to coarse gravel (Guttentag et al., 1984).
Well drillers usually record sandstones of the Dakota aquifer as "sandstone," although a few instances of "brown rock" for the sandstone are also present in the lithologic logs. For a well driller to recognize a sandstone that would be productive for a well, it was assumed that the hydraulic conductivity would be approximately equivalent to fine to medium sand. Although Dakota sandstone can have chemical precipitates (mainly ferric oxide or oxyhydroxides and calcite) partially filling pore spaces, the strata can also include fractures that increase permeability. In some subsurface portions of the Dakota, the sand is uncemented and no precipitate fills pore spaces.
When examining the lithologic log in a WWC5 form, the total thickness of sandstone was estimated as the sum of the intervals designated only as sandstone, plus approximately two-thirds of an interval with sandstone and other lithologies (such as shale, soapstone, or limestone) in which sandstone was listed first, plus about one-third of those intervals in which the sandstone was listed after some other terms. On some logs, the driller included a description of the relative permeability of Dakota sandstone strata (such as poor, fair, good, very good); on others, the driller indicated the percent sandstone in an interval of multiple lithologies; and on several logs, the driller listed relative percentages for both HPA aquifer units and Dakota sandstones. A number of lithologic logs indicated one or more intervals of the Dakota aquifer that "took water" or where circulation was lost. More weight was given to these sandstone intervals than others without such indication. All of this detailed information was used, where present, to assist in the percent yield calculation.
The total thickness of productive HPA or alluvial sediments overlying Dakota units in a well completed in both of these aquifers was estimated by summing the thicknesses of fine sand through gravel units recorded on a lithologic log. A foot of fine sand was assumed to be equivalent to about a half-foot of Dakota sandstone, fine to medium sand about the same as a unit of sandstone, medium to coarse sand about twice that of sandstone, sand and gravel approximately four to five times that of sandstone depending on the description of the sand and gravel, and gravel about six times that of sandstone. Similarly to the estimates for the Dakota sandstone, the thicknesses of productive units in the overlying unconsolidated aquifer that were listed as secondary to fine-grained lithologies (clay, silt) were assumed to be about one-third of that interval. Mixtures of productive lithologies--for example, fine to medium sand and gravel--were adjusted accordingly.
The percent yield of the Dakota aquifer from the total well yield was estimated as the sum of the Dakota sandstone divided by the total equivalent of overlying productive HPA or alluvial sediment plus the Dakota sandstone sum. If the percentage was less than 5%, the contribution of the Dakota aquifer to the well yield was assumed to be insignificant and the well was not designated as producing from the Dakota. A percentage greater than 5% but less than 14% was generally rounded to 10%; several wells with between 14% and 16% were designated to have 15% Dakota sandstone yield. Percentages of about 16% and above were rounded to the nearest 10%. A percentage greater than 95% was considered to be essentially all Dakota sandstone yield with insignificant contribution from overlying unconsolidated sediment. The accuracy of the values depends on the quality of the lithologic logs, the interpretation of the logs and other data, and the assumption of relative hydraulic conductivities for the different strata. The estimated uncertainty in the percentages is ±10% for the 10-20% and 80-90% ranges and ±20% for the 30-70% range for most of the wells with well logs.
In the early stages of the percent well yield determination, the estimates were less accurate than later because the process improved with experience. Estimates improved as more time was spent in calculating the relative yield of all the permeable units in an overlying unconsolidated aquifer and in the Dakota aquifer. For wells in the HPA area, if a WWC5 record indicated that a lithologic log was attached and no such log was actually attached, an estimate of well yield was assigned based on available information. For example, if the interval between the HPA bedrock depth and the bottom of the completed well exceeded the saturated thickness of the HPA, then 70% HPA and 30% Dakota yield was assigned initially. Later, the percent yield value assigned for records without attached logs was based on additional information for wells surrounding that well
b. PDs without WWC5 well logs
For PDs located outside of the extents of the High Plains and alluvial aquifers, the location was examined relative to the confined and unconfined Dakota aquifer and to the water quality in the upper Dakota aquifer to make sure that the location was consistent with a supply well in the Dakota. These wells were assigned a percent yield of 100% for the Dakota aquifer.
For PDs located within the HPA extent that included a reported well depth in WRIS, the depth below the bedrock surface underlying the HPA was considered in the percent yield estimation, along with information for nearby wells in the Dakota that have WWC5 records. The WRIS data for a PD sometimes include well depths reported for different years that do not agree with one another. Based on comparison with well depths in WWC5 records, the earliest reported depth value appears to be more accurate; later values sometimes were substantially different as well as being obviously erroneous. A shapefile of contours for the bedrock surface with a 25-ft (7.6-m) interval was used in ArcGIS Explorer to facilitate the examination. The depth of the bedrock surface based on WWC5 lithologic logs was also considered for some wells in the same or adjacent sections to help determine actual bedrock depth because of the uncertainty in the mapped bedrock surface. More weight was given to a depth based on a lithologic log contact because the bedrock surface coverage is a regionally averaged coverage and locally can be in error by as much as 50 ft (15 m) or more.
The uncertainty in the percent Dakota for these wells is expected to be substantially greater than for the wells with well-log records. Although some of the wells to which some Dakota yield was assigned may have substantially less or even no significant Dakota yield, this is probably offset by other wells that could have some yield from the Dakota that were not identified based on the above procedure and available information. This would be the case for those wells that have reported depths less than 50 ft (15 m) below the actual bedrock surface but that are also screened in sandstone, and for wells completed to a depth of greater than 50 ft (15 m) below the actual HPA bedrock surface in areas where local contours in the bedrock surface map of Macfarlane and Wilson (2006) are deeper than actual.
If no depth information exists for a PD with a DWR Dakota code, then the percent Dakota was estimated based on an average of the values for the surrounding wells that include the Dakota aquifer.
2. PDs within the Dakota extent and with DWR aquifer codes other than the Dakota aquifer or with no aquifer code
a. PDs with WWC5 well logs outside the HPA and alluvial aquifer extents
The WWC5 record was examined to verify that the well was screened in Dakota strata and to determine whether the screened interval included any overlying consolidated material that is saturated. Nearly all of these wells were assigned 100% Dakota. If a well included overlying permeable sediment, the procedure in section 1a was followed for estimating the percent Dakota yield. Several wells with no aquifer code were found to be completed in the Dakota aquifer.
b. PDs within the HPA extent and with well depths greater than 50 ft (15 m) below the bedrock surface underlying the HPA
If a WWC5 record exists for the PD, the well depth in the well log record was used and the procedure in section 1a was followed to estimate the percent Dakota yield. For wells without WWC5 records but with a reported WRIS depth, the procedure in the second paragraph in section 1b was followed. Several wells with aquifer codes other than for Dakota system strata were found to include the Dakota aquifer. Many wells with no aquifer codes were found to be partially or solely completed in the Dakota aquifer.
The procedures in section 2 could miss characterizing wells that produce partially from the Dakota aquifer within productive parts of the HPA, that have no Dakota-related aquifer code assigned by the DWR, and that have no well log or reported depth. USGS and KGS reports on sandstone aquifers in southwest Kansas and KGS bulletins on the geohydrology of selected counties, which were published during the mid-1960s to mid-1980s (Bayne et al., 1971; Fader et al., 1964; Hodson, 1965; Kume and Sponazola, 1982, 1985; Lobmeyer and Weakly, 1979; McNellis, 1973), were examined for records of wells producing primarily or partially from the Dakota aquifer. These records were compared to the list obtained by the above procedures and to WRIS and WWC5 records; more than a dozen wells were added based on this additional review.
Wells without Water Rights
Wells in Kansas classified as for "domestic" uses do not need a water right. Wells that pump water primarily from the Dakota aquifer for "domestic" uses tend to be distributed in areas outside the extents of alluvial aquifers and the HPA. For example, Bayne et al. (1971) listed 210 wells used for some water supply purpose in Ellsworth County in 1961. Of these, 181 were used for domestic and stock purposes and the 29 others were used for public supply, industry, and irrigation. Domestic and stock wells in the list that produced solely or primarily from the Dakota aquifer numbered 136 (75% of the total domestic and stock wells, 65% of the total wells). Most of the other sources of water were alluvium and terrace deposits of the Smoky Hill River valley that cuts diagonally across the county and thinly saturated deposits of the HPA in southwest Ellsworth County.
WWC5 records for 1975 to early March 2012 for Ellsworth County include a total of 596 wells constructed for domestic (457), lawn and garden (116), and feedlot/livestock (23) use (table 2). Stockwatering rights exist in WRIS for eight points of diversion from groundwater in Ellsworth County, of which seven are active. Three wells also have domestic rights; one of these is no longer an active point of diversion. The priority dates for all of the water rights are 1979 or after. If the eight stockwatering and three domestic wells with water rights are subtracted from the 596 total, then 585 wells were constructed during 1975-2012 for uses that would be classified as "domestic" by Kansas water law and that do not have quantified water rights. The primary water source for about 60% (351) of these wells is expected to be the Dakota aquifer based on the 65% proportion for 1961 and the general appearance of the distribution of wells with WWC5 records on a county map. If the annual rate for constructing Dakota "domestic" wells without quantified water rights between 1962 and 1975 was about the same as the average rate for 1975-2012, then approximately 133 wells would have been drilled during 1962-1975. Thus, the total number of Dakota wells constructed for "domestic" purposes would have been about 620 based on 136 for the 1961 list in Bayne et al. (1971), 133 for 1961-1974, and 351 for 1975-2012. Plugging records in the WWC5 data base for domestic, lawn and garden, and feedlot/livestock uses sum to 237 for 1975-2012. If 60% (142) of these were assumed to have drawn water predominantly from the Dakota aquifer, then the number of current Dakota wells in Ellsworth County would be approximately 480. This number was further reduced by 5% to reflect wells that were either plugged before WWC5 records began in 1975 or are currently inactive, giving a total of about 450 currently active "domestic" wells drawing part or all of their water source from the Dakota aquifer.
Similar data were used to estimate the number of wells classified as for "domestic" uses with primarily a Dakota aquifer source in Ottawa and Rush counties. Mack (1962) listed 175 wells used for some supply purpose in Ottawa County during 1957-1958. Of these, 164 were for domestic and stock purposes and the 11 others were for public supply and irrigation. Domestic and stock wells producing solely or primarily from the Dakota aquifer numbered 136 (83% of the total domestic and stock wells, 78% of the total wells). McNellis (1973) listed 222 wells used for some supply purpose in Rush County during 1959-1960. Of these, 60 were domestic and stock wells and the 162 others were used for public supply, industry, and irrigation. Domestic and stock wells producing solely or primarily from the Dakota aquifer numbered 26 (43% of the total domestic and stock wells, 27% of the total wells).
WWC5 records for 1975-2012 for Ottawa County include 842 wells constructed for domestic (656), lawn and garden (136), and feedlot/livestock (50) use (table 2). Stockwatering rights exist in WRIS for 17 points of diversion from groundwater in Ottawa County, of which 13 are active. One domestic well has a water right. The priority dates for all but one of the stockwatering rights are 1980 and after, and for the domestic well is 2001. If the 17 stockwatering wells and one domestic well with water rights are subtracted from the 842 total, then 824 wells were constructed during 1975-2012 for uses that would be classified as "domestic" by Kansas water law. The primary source for about 70% (577) of these wells is expected to be the Dakota aquifer based on the 78% for the 1957-1958 list of Mack (1962) and the map distribution of WWC5 records (many wells appear to be in alluvial aquifer areas for 1975-2012). If the annual drilling rate for Dakota "domestic" wells for 1959 to 1975 was about the same as the average rate for 1975-2012, then approximately 265 wells would have been drilled during 1959-1975. Thus, the total number of Dakota wells constructed for "domestic" purposes would have been about 980 based on 136 for the 1957-1958 list in Mack (1962), 265 for 1959-1974, and 577 for 1975-2012. Plugging records in the WWC5 data base for domestic, lawn and garden, and feedlot/livestock uses sum to 28 for 1975-2012. If 70% (20) of these were assumed to have drawn water predominantly from the Dakota aquifer, then the number of Dakota wells would currently be about 960. Further reduction for wells plugged before 1975 or currently inactive gives a total of 910 currently active "domestic" wells producing from the Dakota aquifer.
WWC5 records for 1975-2012 for Rush County include 363 wells constructed for domestic (310), lawn and garden (22), and feedlot/livestock (31) use (table 2). Stockwatering rights exist in WRIS for six points of diversion from groundwater in Rush County, of which five are active. The priority dates for two of these water rights are 1972 and 1974 and for the others are 1975 and after. Two domestic water rights exist; the use of water is no longer active from either one. One of the domestic wells has a priority date of 1972, the other 1975. If the five stockwatering and domestic wells with priority dates of 1975 and greater are subtracted from the 363 total, then 358 wells were constructed during 1975-2012 for uses that would be classified as "domestic." The primary source for about one-fourth (90) of these wells is expected to be the Dakota aquifer based on the 27% value for the 1959-1960 list of McNellis (1973). If the annual drilling rate for Dakota "domestic" wells for 1961 to 1975 was about the same as the average rate for 1975-2012, then approximately 36 wells would have been drilled during 1961-1975. Thus, the total number of Dakota wells constructed for "domestic" purposes would have been about 150 based on 26 for the 1959-1960 list in McNellis (1973), 36 for 1961-1974, and 90 for 1975-2012. Plugging records in the WWC5 data base for domestic, lawn and garden, and feedlot/livestock uses sum to 91 for 1975-2012. If 25% (23) of these were assumed to have drawn water predominantly from the Dakota aquifer, then the number of Dakota wells would currently be approximately 129. Further reduction for wells plugged before 1975 or currently inactive gives a total of 123 active "domestic" wells in the Dakota aquifer.
The estimated number of active wells in Ellsworth, Ottawa, and Rush counties classified as for "domestic" use and producing solely or primarily from the Dakota aquifer totals more than 1,490. The number of wells for these three counties in the WWC5 data base that were constructed for "domestic" purposes during 1975-2012 is 1,801. If the total plugged wells in the WWC5 records for these counties (356) and the number of stockwatering and domestic wells with water rights with priority dates after 1974 (34) are subtracted from the constructed total, the result is a "net total" of 1,411 wells for 1975-2012. The ratio of the estimated active Dakota wells to the 1,411 "net total" is 1.05. Table 2 summarizes the data used for the above calculations.
Table 2--Well types and ratios used in the estimation of the total number of "domestic" wells in Ellsworth, Ottawa, and Rush counties.
| Well type or ratio | Ellsworth County | Ottawa County | Rush County | Sum |
|---|---|---|---|---|
| Domestic constructed | 457 | 656 | 310 | 1,423 |
| Lawn and garden constructed | 116 | 136 | 22 | 274 |
| Feedlot or stock constructed | 23 | 50 | 31 | 104 |
| Total constructed | 596 | 842 | 363 | 1,801 |
| Domestic plugged | 225 | 24 | 77 | 326 |
| Lawn and garden plugged | 5 | 0 | 3 | 8 |
| Feedlot or stock plugged | 7 | 4 | 11 | 22 |
| Total plugged | 237 | 28 | 91 | 356 |
| Constructed minus plugged | 359 | 814 | 272 | 1,445 |
| Stockwatering and domestic (WRIS PDs) | 11 | 18 | 5 | 34 |
| Net total (constructed minus plugged and WRIS PDs) | 348 | 796 | 267 | 1,411 |
| Estimated current Dakota "domestic" | 478 | 958 | 129 | 1,565 |
| Estimated current adjusted Dakota "domestic" (minus 5% plugged before 1975 or currently inactive) |
454 | 910 | 123 | 1,487 |
| Ratio adjusted Dakota "domestic"/net total | 1.305 | 1.143 | 0.459 | 1.054 |
Ellsworth, Ottawa, and Rush counties are reasonably representative of the counties in the north-central and central regions (table 3) where the Dakota aquifer is used for water supply. The usable Dakota aquifer in these regions includes both confined and unconfined strata, and unconsolidated aquifers overlying part of the Dakota are mainly alluvial systems associated with stream and river valleys. The total number of active Dakota wells used for "domestic" purposes in the north-central and central regions of Kansas was estimated by multiplying the 1.05 ratio times the "net total" wells for 1975-2012 for these regions. However, for this calculation, an adjustment must be made for the area for which "domestic" wells are summed from the WWC5 data base because not all of the counties in these two regions are underlain by Dakota strata. Thus, no wells from Clay County were considered in the north-central region to approximately balance the area of Washington County that is not underlain by the Dakota aquifer. Similarly, no wells were considered in Saline, McPherson, and Marion counties to offset the area without underlying Dakota strata in Rice County and the part of Barton County south of the Arkansas River where the HPA is essentially the only aquifer used.
Table 3--List of counties for different regions of the Dakota aquifer in Kansas.
| Kansas region | Counties in region |
|---|---|
| North-central | Clay, Cloud, Ottawa, Republic, Washington |
| Central | Barton, Ellis, Ellsworth, Lincoln, Marion, McPherson, Rice, Rush, Russell, Saline |
| South-central | Edwards, Pawnee |
| West-central | Lane, Ness, Scott, Trego, Wichita |
| Southwest | Clark, Finney, Ford, Grant, Gray, Hamilton, Haskell, Hodgeman, Kearny, Meade, Morton, Seward, Stanton, Stevens |
The total number of domestic, lawn and garden, and feedlot/livestock wells constructed from 1975 to early 2012 in the adjusted areas of north-central and central Kansas is 9,205 (table 4). The proportion of the total "domestic" wells constructed during 1975-2012 in Ellsworth, Ottawa, and Rush counties that have post-1974 stockwatering and domestic water rights is 1.89% (34 WRIS wells divided by 1,801 wells). If this percentage is subtracted from the "domestic" well total in the adjusted north-central and central Kansas areas, the result is 9,031 wells. Subtracting the total number of plugged wells for "domestic" uses (1,410) gives a "net total" of 7,621. Application of the 1.05 ratio of Dakota wells to "net total" wells for Ellsworth, Ottawa, and Rush counties gives an estimate of 8,000 "domestic" wells with a primary water source from the Dakota aquifer for these two regions (table 4).
Table 4--Well types and ratios used in the estimation of the total number of "domestic" wells in north-central and central Kansas.
| Well type or ratio | North-central minus Clay County |
Central minus Saline, McPherson, and Marion counties |
Sum |
|---|---|---|---|
| Domestic constructed | 1,597 | 4,691 | 6,288 |
| Lawn and garden constructed | 297 | 1,871 | 2,168 |
| Feedlot or stock constructed | 265 | 484 | 749 |
| Total constructed | 2,159 | 7,046 | 9,205 |
| Domestic plugged | 284 | 864 | 1,148 |
| Lawn and garden plugged | 4 | 123 | 127 |
| Feedlot or stock plugged | 40 | 95 | 135 |
| Total plugged | 328 | 1,082 | 1,410 |
| Constructed minus plugged | 1,831 | 5,964 | 7,795 |
| Estimated ratio stockwatering and domestic (WRIS)/total constructed |
0.0189 | 0.0189 | |
| Estimated stockwatering and domestic (WRIS PDs) | 41 | 133 | 174 |
| Net total (constructed minus plugged and WRIS PDs) | 1,790 | 5,831 | 7,621 |
| Estimated ratio adjusted Dakota "domestic"/net total | 1.05 | 1.05 | |
| Estimated adjusted Dakota "domestic" | 1,880 | 6,120 | 8,000 |
A major portion of the south-central, west-central, and southwest regions of the Dakota aquifer (table 3) are overlain by the HPA, which is the primary source of water in these areas. Similarly to the north-central and central regions, the counties in the south-central and southwest regions were adjusted to reflect areas that are either not underlain by the Dakota aquifer or where the Dakota aquifer may not be used at all where it overlies Dakota strata. For the south-central region, WWC5 records in Edwards County were not included; thus, only Pawnee County wells were considered. In the southwest region, WWC5 records were not included for Clark, Meade, and Seward counties to offset the areas of Morton and Stevens counties that are not underlain by the Dakota aquifer.
The total number of domestic, lawn and garden, and feedlot/livestock wells constructed from 1975 to early 2012 in west-central Kansas and the adjusted areas of south-central and southwest Kansas is 8,585 (table 5). Inspection of WIMAS records for some of the counties in southwest Kansas indicates that the proportion of feedlot and domestic wells with water rights is greater than for north-central and central Kansas. Thus, the total number of "domestic" wells was reduced by 5% instead of 1.89% giving 8,156 wells. Subtracting the number of plugged wells for "domestic" uses gives a "net total" of 6,346 wells. The 1.05 ratio of Dakota wells to "net total" wells is expected to be too high a ratio for these areas because in most of the counties the HPA is the predominant water source. However, in much of these regions either not containing the HPA or with only thinly saturated HPA, the Dakota aquifer (along with some underlying Morrison-Dockum aquifer) is the main water source. A ratio of 0.5 was used as a rough estimate of the ratio of Dakota wells to the "net total" wells used for "domestic" purposes. This number was selected to be less than the ratio (0.65) of two fractions: the first (0.083) is the number of permitted water-right wells in the Dakota aquifer divided by the total permitted wells in all aquifers in south-central, west-central, and southwest Kansas; the second (0.129) is the analogous value for north-central and central Kansas. This gives an estimate of 3,170 "domestic" wells with a primary water source from the Dakota aquifer for these three regions (table 5).
Table 5--Well types and ratios used in the estimation of the total number of "domestic" wells in south-central, west-central, and southwest Kansas.
| Well type or ratio | South-central, Pawnee County only |
West-central | Southwest minus Clark, Meade, and Seward counties |
Sum |
|---|---|---|---|---|
| Domestic constructed | 657 | 1,379 | 5,067 | 7,103 |
| Lawn and garden constructed | 28 | 79 | 77 | 184 |
| Feedlot or stock constructed | 132 | 392 | 774 | 1,298 |
| Total constructed | 817 | 1,850 | 5,918 | 8,585 |
| Domestic plugged | 46 | 284 | 1,079 | 1,409 |
| Lawn and garden plugged | 7 | 3 | 101 | 111 |
| Feedlot or stock plugged | 16 | 79 | 195 | 290 |
| Total plugged | 69 | 366 | 1,375 | 1,810 |
| Constructed minus plugged | 748 | 1,484 | 4,543 | 6,775 |
| Estimated ratio stockwatering and domestic (WRIS)/total constructed |
0.05 | 0.05 | 0.05 | |
| Estimated stockwatering and domestic (WRIS PDs) | 41 | 92 | 296 | 429 |
| Net total (constructed minus plugged and WRIS PDs) | 707 | 1,392 | 4,247 | 6,346 |
| Estimated ratio adjusted Dakota "domestic"/net total | 0.5 | 0.5 | 0.5 | |
| Estimated adjusted Dakota "domestic" | 354 | 696 | 2,123 | 3,173 |
The total number of "domestic" wells with a primary source from the Dakota aquifer in Kansas is estimated as 11,200 (8,000 for north-central and central and 3,170 for south-central, west-central, and southwest Kansas).
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Kansas Geological Survey, Geohydrology
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