Ground-Water Atlas of Colorado Special Publication 53

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Colorado Geological Survey WATER 1EVELSIA091FER CHARACTER /ST /CS Studies by Geldon (1989) indicate that ground -water flow is gener- ally from west to east in the southern part of the basin. The 1978 potentiometric surface in the Cuchara- Poison Canyon aquifer of the southern Raton Basin is shown in Figure 6.7 -7. The 1981 potentio- metric surface in the Raton - Vermejo- Trinidad aquifer of the South- ern Raton Basin is shown in Figure 6.7 -8. In Huerfano County, water can generally be found in the Cuchara- Poison Canyon aquifer at depths of less than 200 feet in the outcrop areas. The aquifer may, however, be dry to a depth of several hun- dred feet where the area is highly dissected by igneous intrusive rocks, as in the vicinity of the Spanish Peaks. (McLaughlin, 1966). The 1989 depth to water in the southern part of the basin is shown on Figure 6.7 -9. The depth to water is deepest in the southeastern part of the basin, where it is more than 200 feet below ground sur- face at higher elevations. 105° 104 °30' 37° 30' � 1 I HUERFANO j 1\ 1 I SI Ritey guilar I I 6 00 r' S v - J ^g00 00 00 ` N OD 1 0 ,� /area Trinidad ` @. Trinidad / pur8afoare I to � / Rifer 1 I LAS ANIMAS I ) /—/ l COLORADO .�I. .. ../ ..._...�..�.._.._.. .._.--- -- -- -i- - --._. NEW MEXICO Modified from Geldon, 1989 EXPLANATION —7200— Potentiometric surface contour; contour interval -200 feet; datum —sea level Figure 6.7 -7. Potentiometric surface in the Cuchara- Poison Canyon aquifer, May 1978, southern Raton Basin. DRAFT There are nearly 1,370 water wells of record, with the Colorado Division of water Resources (DWR), in the Colorado portion of the Raton Basin. The distribution of those wells and wells used in historical U.S. Geological Survey investigations is presented in Figure 6.7 -1. The depth distribution of permitted wells of record with DWR is shown on Figure 6.7 -10. This figure shows that deep- er wells are generally concentrated along the eastern margin of the basin, with shallow wells dominating the central portion of the basin. Wells in the southern portion of the basin are not shown because the lack of a land -grid survey in this area precludes the plotting of well locations. The majority of the permitted wells in the Raton Basin are less than 150 feet deep, with 90 percent of all wells completed at depths less than 450 feet (Figure 6.7 -11). The mean depth for the wells in this data set is 188 feet, and the median depth is 115 feet. 37' 105° 104° 30' HUERFANO } 1 m No � ° I 1 n+ S Apishapa � PdG i1 �voo 00 = r J J I 1p y� a � r �_ �r Limdad � � // pu'8atoire/ Trinidad 1 I I TtiveY Lake O U LAS ANIMAS I t ) l/ N COLORADO rIp .. .✓ NEW MEXICO — . - - - - -- EXPLANATION Modified from Geldon, 1989 7000— Potentiometric surface contour; contour interval -100 feet; datum —sea level Figure 6.7 -8. Potentiometric surface in the Raton- Vermejo- Trinidad aquifer, April —July 1981, in the southern Raton Basin. GROUND -WATER ATLAS OF COLORADO The depths to water reported in the DWR database for given well depths vary tremendously due to the large areal extent and the varying ages of the data. A scatter plot of reported depths to water versus well depths is presented as Figure 6.7 -12. In an attempt to reduce the variability of this data, a moving average trendline has been applied to the water -level data. This trendline indicates that the water level in any given well may be anticipated to occur at about one -third of the well depth common to an area. 37' 105° 104' 30' H U E R F A N O 1 m o ID ml' /- (0 ..s g�ilar ml S Ape >ltapa r 3 \ QaG P it — h Tnnidad Trinidad /E1:r rake 00 1\ LAS ANIMAS ) ..�..L..�.._ .._.._., COLORADO.. ._..._.:. NEW MEXICO ••_.. —• EXPLANATION Modified from Geldon, 1989 Depth to Water in Feet Less than 100 ® Area where aquifers 100 to 200 are covered by Huerfano Formation More than 200 Figure 6.7 -9. Depth to water in the southern Raton Basin. SP 53