Lost River - Karst Information Portal

miles (Bassett, 1976 and 2000) to the north
of the Lost River Basin. See Figure PP for the
limits of this sub-basin in a new map by Bassett
(2000). It is the most upstream of the two rises.
The True Rise of Lost River is a less picturesque
and less accessible feature located about 0.75
miles to the south (Figure 60 and 61).
The Orangeville Rise and the Rise of Lost
River would have been flooded to a depth of
about 15 feet by a proposed Soil Conservation
Service dam on Lost River near Prospect. The
project was defeated in the early 1970s by a
coalition of environmental groups, cavers,
and landowners whose property would have
been flooded. Horton Hobbs and Robert
Armstrong, along with many other cavers,
were instrumental in preparing documentation
and arguments for the National Speleological
Society as part of the still-active Lost River
Conservation Task Force of the NSS. The
Soil Conservation Service once had long-term
plans to make drainage improvements to the
Lost River basin, and a private landowner once
purchased much of the Lost River downstream
of the rises with the idea of creating a resort
lake via a dammed impoundment. The rises
supposedly would not be inundated, even
at high lake levels. The Orangeville Rise was
given to the Indiana Karst Conservancy by
The Nature Conservancy in 1998 (verbal
communication, 2007, Keith Dunlap) and,
like Tolliver Swallowhole and Wesley Chapel
Gulf, has been declared a National Natural
Landmark by the National Park Service.
[Downstream from the Orangeville Rise,
the Lost River valley widens considerably and
is filled to a depth of several feet with alluvium.
Powell (1963) speculated that the rises,
interpreted to be alluviated, might once have
been open gravity-flow springs during early or
middle Pleistocene time. In recent years Powell
and others have re-thought this hypothesis
because diving of the True Rise showed that it
is over 180 feet deep, far below the bottom of
the alluviated channel of Lost River. See Figure
61. (KS)]
The drainage basin supplying the
Orangeville Rise has been delineated, generally
Lost River Field Trip
at least, by the dye tracings discussed previously.
The Orangeville Rise is known to drain much
of the Crawford Upland north of Orangeville,
as well as a large section of the Mitchell Plain
north of the Dry Bed. Based on the dye tracing
work, the Rise is believed to drain over 49
square miles of the basin. The hydrology of
the area is a little more complex than was once
thought. During periods of excessive rainfall,
much of the water supplying the Rise leaks
to the surface via several storm water rises
(Mathers Rises) located principally along the
Dry Bed in SW ¼ , Sec 34, T3N, R1W, about 3
miles to the north. (See Figure 44.)
The water issuing from the Orangeville Rise
surges upward about 20 feet from openings
under a ledge of Ste. Genevieve Limestone
which forms an overhang about 110 feet across.
Turbid storm waters boil up with great force,
and flood backwaters frequently overflow the
deeply incised surface channel downstream
from the spring and cover the bedrock face
above the spring. A minimum flow of 9 cubic
feet per second (cfs) and a maximum flow of 185
cfs were reported by Bassett (1976, pp 80 and
83). Maximum discharge at the Rise probably
does not exceed 250 cfs. Great variation of flow
is characteristic of most karst springs, especially
those fed by large or extensive cavern systems.
The valley of Lost River downstream of the
Orangeville Rise (and True Rise) is alluviated
to a depth of 20 to 30 feet. Most of the valleyfill
material is alluvium and colluvium of
Pleistocene age.
In 1973 the chemical character of the
water emerging at Orangeville was calcium
bicarbonate. Calcium is the dominant cation,
making up 71.7 to 80.7 percent of the total
cation molality, with a mean of 75.9 percent.
Bicarbonate is the main anion, totaling from
80.7 to 88.3 percent of the anion molality, with
a mean of 85 percent. Sulfur isotopic studies
show a mean isotope 34S (SO 4 ) of 11.51 %,
indicating shallow flow input and low residence
time of the water.
The True Rise of Lost River is located 0.75
miles south and downstream of the Orangeville
Rise. It consists of a channel about 100 feet
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