Lecture 34

Dakota Regional Aquifer

Swenson, 1968

GSA Bull V.79

P.163-182

Outcrop on Black Hills

	very narrow
	16 inches of precipitation per year.
	few streams cross
	Began drilling 1896

South Dakota ~ 100,00 gpm (Darton, 1908)

1960 40 gpd (36 mgd from flowing wells)

Much more discharge than recharge-Why?

Meinzer - Compressibility and elasticity of aquifer.

Removing water from storage.

"Head will decline before cone intercepts western outcrops of sandstone."

Dakota is actually a few separate aquifers.

Madison Group is below Dakota Aquifer.

	Madison has much dissolution at outcrop areas.
	Streams lose all flow across recharge area.
	Madison paleo karst at depth eroded near Missouri River,

Flow from Madison up into Dakota

	increase in Na+ and Cl-
	decrease in Ca+2 and SO42-

Schematic cross section showing major aquifers and confining layers.

(Swenson, 1968) GSA Bull. v. 79 p. 163-183.

Major aquifer systems in South Dakota.

Schematic cross section showing minor aquifers and confining layers

overlying Dakota Aquifer.

Minor aquifer systems above the Dakota Sandstone.

Virgin potentiometric surface for the Dakota Aquifer, as mapped by

Darton (1909).

Isopach map of the Madison Group.

Types of water in the Dakota Sandstone and equivalent strata, and

limestones of the Madison Group in South Dakota.

Simulated virgin flow conditions (from Bredehoeft et al., 1983).

Schematic diagram of ground-water flow in the Great Basin.

Common relationships between ground water and surface water in

the Great Basin Region.

Figure 9.39 Ground-water regions of the United States. Source:

R.C. Heath, U.S. Geological Survey Water-Supply Paper 2242, 1984.

ENV 302 - Lectures