Corps AirGround Combat Center [MCAGCC], Twen-
represented strongly reducing conditions.
tynine Palms, California (Lichvar and Pringle 1993), are
Domed mudcracks with algal flakes. This feature
Deadman Lake, Dry Lake, Emerson Lake, Lavic Lake,
was observed at WSMR and other areas of the
and Mesquite Lake. They range in size from about 70.82
desert southwest with prolonged water ponding.
to 1092.65 hectares (175 to 2700 acres).
Oxidized rhizospheres in sparsely vegetated areas.
None of the playas on the MCAGCC were three-
Ponded water (in OHW definition).
parameter wetlands, so the OHW line was used to de-
Drift lines (in OHW definition).
termine the limits of jurisdiction. Ponded water and other
Smooth, gray, level surface on playa or pan. A
indicators, including mud cracks, drift lines, vegetation,
smooth level surface is associated with ponded
topography, and soil texture, were used to establish the
surfaces. The gray tone is associated with reduced
OHW line. Other indicators included ruts made by off-
surface conditions resulting from ponded water.
road vehicles (ORV) during previous wet periods. The
Mud cracks filled with wicked salt (on alkali flats).
latter indicators were observed at the edge of ponded
In areas where water ponds the longest, zones of
water and were applied elsewhere after the water had
mud cracks with salt crystals protrude about 1 to
receded. Interestingly, the soft playas (nonjurisdiction-
2 cm (0.39 to 0.78 in.) above the surface.
al) were found neither to pond water nor to have ground-
Polygonal patterns in salt pan surfaces filled with
water closer than 1 m (3.28 ft) from the surface.
protruding salt crystals to heights of 1 to 3 cm (0.39
to 1.18 in.).
Fort Bliss, Texas, and New Mexico (FBA)
Rubberized surface (on alkali flats). In depressional
The playas at FBA (Lichvar and Sprecher 1998) gen-
landscape positions within the alkali flats,
erally lacked one or more of the three parameters of a
cryptobiotic soil surfaces have a rubberized tex-
wetland; consequently the OHW line was used to de-
ture.
termine the limits of jurisdiction. Ponded water and other
Secondary indicators included
indicators of hydrology were used to establish the OHW
Thematic Mapper (TM) satellite image with areas
line; other indicators included mud cracks, drift lines,
of ponded water combined with a level, smooth
algal crusts, and soil surface features. Secondary indi-
surface.
cators included hummocks, which develop as a result
Sloped pans. Sloped, flat surfaces located
of moist soil processes; and the presence of Cow Pan
downslope of dune fields had pans that were
Daisy (Verbesina encelioides), which is common on the
unvegetated and lacked hydric soil indicators, but
pans. Gas holes (a surface collapse feature described
were moist in the upper 15.24 cm (6 in.) of the soil
by Stone [1956]) were located on the surface of the pla-
without immediately preceding rains.
yas along with other indicators of ponded water. These
Unvegetated landform (on dry lakes). The dry
were typically 0.30480.4572 m (11.5 ft) across and
lakes scattered throughout stabilized dune areas
15.2430.48 cm (612 in.) deep. They are reportedly
were a depressional landform feature typically de-
found on other playas in the southwest as well.
void of vegetation due to high salt content soils
and seasonal ponding.
White Sands Missile Range (WSMR),
Patterned ground (on salt pans). Large mudcrack
New Mexico
polygons scattered across the salt pan surface.
A number of site-specific indicators for OHW were
10YR 5/3 streaks and blotching on salt pans. In
developed (Lichvar and Sprecher 1999). Ponded water
these high-salt-content soils, these faint iron seg-
and other indicators (mud cracks, drift lines, algal flakes,
regations indicated seasonal fluctuation of near-
soil surface features, flow channels, sulfur stained sur-
surface groundwater.
faces, and bed and bank morphology) were used to
Large salt crystals (restricted areas). Soil profiles
determine OHW. Primary indicators were as follows:
with salt crystals greater than 2 mm (0.08 in.) at an
Surface colors or blotches of black, green, or gray,
occurrence of 5% or more have been observed at
often accompanied by an odor of H2S. Some of
sites with saturated soils during wet seasons.
the pans and playas have a high content of gypsif-
Raised and mounded rings (on alkali flats).
erous material; as a result of shallow ponding, it is
Sierra Army Depot, Nevada
assumed sulfur is being reduced and creating col-
ored streaks or blotches.
Basic assumptions for indicators were made as fol-
Iron segregation. Redoximorphic segregation fea-
lows (Doub and Colberg 1996): For vegetation, salt grass
tures develop under aquic conditions because of
was regarded as "facultative" for playa edge--grow-
ing inside and outside of playa boundaries. Atriplex
chemical reactions in the soils; while the segrega-
tion of iron was not prominent, the authors felt it
spp. were considered "facultative upland," rarely grow-
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