Wind River Basin hydrostratigraphy

The Wind River Basin hydrogeologic units defined for this study are described below, youngest to oldest (Plate II, far right column). Bracketed […] classifications below are from the Statewide Framework Water Plan (WWC Engineering, 2007). Below the major alluvial aquifer at the land surface and above the thick, widespread Upper Cretaceous Cody major confining unit are three Tertiary or Upper Cretaceous major sandstone aquifers (Split Rock, White River, Lance) and two major confining units (Indian Meadows, Meeteetse-Lewis); the aquifers are generally accessible in the central basins. Below the Cody confining unit and above the Precambrian basal major confining unit, lower Mesozoic and Paleozoic hydrogeologic units include one major sandstone aquifer (nugget) and five major limestone aquifers (Tensleep, Madison, Darby, Bighorn, Flathead); these aquifers are generally accessible in and near outcrop along the basin margins.

Where present with sufficient thickness, Quaternary unconsolidated deposit aquifers – alluvium and terrace, landslide, eolian, and glacial deposits – constitute important [Major] aquifers in the basin. Upper Tertiary bedrock aquifers crop out only along the southernmost margin of the Wind River Basin. Lower Tertiary and Upper Cretaceous aquifers are lenticular, discontinuous sandstone bodies that are hydraulically isolated to varying degrees by interbedded finegrained confining units. The Tertiary and Upper Cretaceous hydrogeologic units above the Cody [Major] confining unit include, youngest to oldest:

  • the Split Rock [Major Sandstone] aquifer
  • the White River [Marginal] aquifer
  • the Aycross–Wagon Bed confining unit [Marginal aquifer]
  • the Wind River [Major Sandstone] aquifer
  • the Indian Meadows [Major] confining unit
  • the Fort Union–Lance aquifer, including:
    • the Fort Union [Minor] aquifer
    • the Lance [Major Sandstone] aquifer
  • the Meeteetse–Lewis [Major] confining unit
  • the Mesaverde [Minor] aquifer, including:
    • the Teapot [Minor] Sandstone aquifer
    • the Middle confining unit
    • the Parkman [Minor] Sandstone aquifer
    • a confining unit (Wallace Creek tongue of the Cody Shale)
    • the Fales [Minor] Sandstone aquifer

Immediately below the Cody [Major] confining unit, the lower and middle Mesozoic aquifers and confining units aquifer system is composed of [Major], [Minor], and [Marginal] aquifers and confining units dominated by sandstone, siltstone, and shale lithologies. While some of the aquifers are lenticular and discontinuous, they are generally more continuous and laterally extensive than the lower Tertiary and Upper Cretaceous aquifers above the Cody Shale. The lower and middle Mesozoic aquifers and confining units include substantial confining units that hydraulically isolate some component aquifers of the system. The lower and middle Mesozoic aquifers and confining units aquifer system includes, youngest to oldest:

  • the Frontier [Minor] aquifer, including:
    • a basal confining unit
  • the Mowry–Thermopolis [Major] confining unit, including:
    • the Mowry [Major] confining unit
    • the Muddy Sandstone aquifer (locally interbedded within the Mowry and Thermopolis shales)
    • the Thermopolis [Major] confining unit
  • the Cloverly [Minor] aquifer
  • the Morrison confining unit [Minor aquifer]
  • the Sundance–Nugget aquifer, including:
    • the Sundance [Minor] aquifer
    • the Gypsum Spring confining unit [Marginal aquifer]
    • the Nugget Sandstone [Major Sandstone] aquifer
  • the Chugwater–Dinwoody [Marginal] aquifer and confining unit, including:
    • the Chugwater [Marginal] aquifer, including:
      • the Popo Agie confining unit
      • the Crow Mountain [Marginal] aquifer
      • the Alcova confining unit
      • the Red Peak [Marginal] aquifer
    • the Dinwoody confining unit [Marginal aquifer]

Although included here in the lower and middle Mesozoic aquifers and confining units (Plate II), the Dinwoody Formation is variously considered the uppermost unit of the underlying Goose Egg-Phosphoria aquifer and confining unit. The mostly Permian Goose Egg–Phosphoria [Minor] aquifer and confining unit separates the Lower and middle Mesozoic aquifers and confining units system from the Paleozoic aquifer system.

The Paleozoic aquifer system includes Pennsylvanian through Ordovician carbonate aquifers that are well known for producing high volumes of groundwater at and near the flanks of the Laramide uplifts surrounding the basins where permeability has been structurally enhanced by solutionenlarged solutionenlarged fractures. The component Paleozoic aquifer system hydrogeologic units are, youngest to oldest:

  • the Tensleep [Major Limestone] aquifer
  • the Amsden [Marginal] aquifer
  • the Madison [Major Limestone] aquifer
  • the Darby [Major Limestone] aquifer
  • the Bighorn [Major Limestone or Minor] aquifer

The Paleozoic aquifer system is underlain by the Cambrian Gallatin–Gros Ventre confining unit, the Cambrian Flathead aquifer, and the Precambrian basal confining unit, described as follows:

  • the Gallatin–Gros Ventre confining unit, including:
    • the Gallatin confining unit [Minor aquifer]
    • the Gros Ventre confining unit [Minor aquifer]
  • the Flathead [Major Limestone] aquifer
  • the Precambrian basal [Major] confining unit

The Precambrian basement complex is a marginal aquifer locally where it is exposed and fractured in the cores of the Laramide uplifts, where thin and disconnected soil, deeply weathered bedrock, and shallow fractures provide transmissive zones. Where these conditions do not exist at land surface, and virtually everywhere in the subsurface, the Precambrian basement is the basal confining unit for the structural groundwater basins in the WBRB and throughout Wyoming.

Reference View complete Wind/Bighorn Basin Water Plan