WETLANDS, Vol. 23, No. 3, September 2003, pp. 577–589
q 2003, The Society of Wetland Scientists
PAST AND FUTURE IMPACTS OF WETLAND REGULATIONS ON PLAYA
ECOLOGY IN THE SOUTHERN GREAT PLAINS
David A. Haukos1 and Loren M. Smith2
1
U.S. Fish and Wildlife Service
MS 2125
Texas Tech University
Lubbock, Texas, USA 79409-2125
2
Wildlife and Fisheries Management Institute
MS 2125
Texas Tech University
Lubbock, Texas, USA 79409-2125
Abstract: Playa wetlands provide functions critical to the existence of life on the High Plains portion of
the Great Plains, including surface drainage, aquifer recharge, and wildlife habitat. These small, circular,
isolated depressional wetlands with closed watersheds have a dynamic, unpredictable hydroperiod, which is
essential to the maintenance of biodiversity. Most numerous in the Southern High Plains of northwestern
Texas and eastern New Mexico, playas have been impacted by sedimentation, pit excavation, road construction, industrial and municipal wastewater, feedlot runoff, urban development, overgrazing, and deliberate
filling. Despite being declared, as a wetland class, jurisdictional ‘‘waters of the United States’’ since 1977,
regulations and laws for conservation of wetland functions have seldom been applied to playas. The January
2001 Supreme Court decision, Solid Waste Agency of Northern Cook County (SWANCC) v. United States
Army of Corps of Engineers, likely eliminated federal regulation of impacts covered by the Clean Water Act
in all but a few playas. Although still subject to the Federal ‘‘Swampbuster’’ provision enacted by the 1985
Food Security Act, extended natural dry periods allows for frequent cultivation and other activities in playas
without incurring violation, contributing to the continued degradation of playa functions. None of the states
with significant numbers of playas have regulations for the conservation of playa functions. Suggestions for
the successful future conservation of playas and their associated functions include (1) increased promotion
and implementation of existing federal and state conservation programs specifically for playas; (2) proposed
state regulations for playa conservation; (3) recognition of agricultural impacts on wetland determinations;
(4) creation of Wetland Management Districts to preserve intact, functioning playas; and (5) increased public
education on the value of playas.
Key Words:
playa wetlands, regulations, Southern High Plains
INTRODUCTION
wetland occurring primarily in the High Plains region
of the western Great Plains. Each occurs within a
closed watershed and, as the term recharge implies,
only receives water naturally from precipitation and its
associated runoff. Significant natural loss of collected
water is only through evaporation, transpiration, and
infiltration.
Although some geologists disagree about the processes involved in playa formation, Great Plains playas
are formed and maintained through a combination of
dissolution of subsurface basin material and wind deflation (Osterkamp and Wood 1987, Gustavson et al.
1995, Reeves and Reeves 1996). Playas are also characterized as sinks for material transported by precipitation runoff and have unpredictable hydroperiods with
extended dry periods. Further, conflicting biological
Few wetland scientists outside of the Great Plains
can accurately describe playa wetlands. For example,
Mitsch and Gosselink (2000) and the National Research Council (1995) have inaccurately defined playa
wetlands by comparing them to prairie potholes in the
northern Great Plains, indicating differences only in
geologic origin (Smith 2003). Playas differ from other
freshwater wetlands in hydrology, soils, plant communities, landscape location, and other ecological attributes (Smith 2003). Geologists also have struggled
with definitions of playas (Motts 1970, Rosen 1994),
but few of their definitions are of value to wetland
scientists because of the lack of consideration of playa
ecological structure and function. For purposes of this
paper, a ‘‘playa’’ is a shallow depressional recharge
577
578
opinions concerning the ecological structure and function of playas dominate the literature. Such incongruity
about the origin, hydrology, and ecology of playas has
resulted in frequent confusion when applying and enforcing regulations and laws that should pertain to
these unique wetlands.
Within the Great Plains, there are probably more
than 30,000 playas, but the majority, at least 25,000,
occur in the Southern Great Plains from southeastern
Colorado and southwestern Kansas south through the
Southern High Plains (SHP) of eastern New Mexico
and west Texas (Guthery et al. 1981). This area is
commonly referred to as the Playa Lakes Region
(PLR). Within that region, approximately 20,000 playas occur in the SHP of New Mexico and Texas, with
nearly 90% of these in Texas. We recognize that playas exist elsewhere (e.g., Rainwater Basin playas in
south-central Nebraska; LaGrange 1997), but because
the majority of playas occur in the SHP of Texas and
most data on playas have been gathered there, we focus on impacts of regulations primarily to playas of
that area.
Playas in the SHP are circular (Luo et al. 1997),
average 6.3 ha in surface area (Guthery and Bryant
1982) and occur in one of the most intensively agriculturally-impacted regions (i.e., combination of cultivation and livestock grazing) of the Western Hemisphere (Bolen et al. 1989). Excluding a few riparian
corridors, playas are the dominant surface hydrographic and topographic feature in the 82,000 km2 SHP.
Although occupying less than 2% of the SHP, functioning playas are keystone ecosystems serving as biological refugia and critical sites of biodiversity in this
semi-arid and intensive agricultural region of the Great
Plains (Haukos and Smith 1994, Smith and Haukos
2002). Additional critical functions of playas on the
SHP include collection and storage of flood waters,
exclusive recharge points for the Ogallala Aquifer, and
sanctuary for native plants (Haukos and Smith 1994,
Haukos and Smith 1997, Smith 2003).
As the terminus of most watersheds in the SHP,
activities occurring in a watershed have the potential
to impact a playa. Probably the most prominent impact
has been the vast amount of sediments entering playas
via water erosion of cultivated watersheds (Luo et al.
1997, 1999). However, impacts also include pesticides
and metals associated with runoff from agricultural activities (Irwin et al. 1996, Thurman et al. 2000, Dennehy et al. 2002). Playas also receive runoff from confined animal feeding operations (CAFO; feedlots), military and industrial associated pollutants, and treated
wastewater. With playas being the main points of the
limited recharge to the underlying Ogallala Aquifer,
material that drains into playas has the potential to
contaminate the aquifer (Zartman et al. 1996, Litke
WETLANDS, Volume 23, No. 3, 2003
2001). Any such contamination has human health implications.
Because scattered individual playas collectively
form the basis for diversity of the region, impairment
of the function of an individual playa contributes to
the decline of biodiversity across a much larger area
than only the impacted wetland. Therefore, successful
conservation of playas and associated flora and fauna
is dependent upon protection of as many playas as
possible in the landscape rather than just attempting to
identify the ‘‘best’’ playas and concentrating efforts
on just a select few wetlands.
Finally, the vast majority of playas (. 99%) are in
private ownership and, therefore, lack protection that
might be provided by nonprofit conservation organizations or governmental agencies. Consequently, conservation of these wetlands is integral to the existence
of life in the region. Conservation success will ultimately depend on the implementation and enforcement
of sound, comprehensive, and realistic governmental
regulations (e.g., incentives, laws) that recognize and
are pertinent to private ownership.
The 9 January 2001 United States Supreme Court
decision, Solid Waste Agency of Northern Cook County (SWANCC) v. United States Army Corps of Engineers, reduced the protection of playas and other isolated wetlands under Section 404 of the Clean Water
Act, which gives the United States Army Corps of
Engineers (USACE) authority to issue permits for the
discharge of dredge or fill material into ‘‘waters of the
United States.’’ The principal finding of the Court was
that use or potential use by migratory birds did not
constitute sufficient justification for a wetland to be
declared a ‘‘water of the United States’’ subject to the
provisions of Section 404 of the Clean Water Act. The
use of the Migratory Bird Rule was the principle authority leading to the declaration of most playas as
‘‘waters of the United States.’’ Only a small percentage of playas, and most prairie wetlands, could possibly be considered ‘‘waters of the United States’’
based on the criteria remaining after the court decision:
(1) being navigable or adjacent to navigable waters
and their tributaries; (2) physically occurring on the
boundary of two states or tribes; (3) fostering other
forms of interstate commerce (e.g., commonly used by
interstate or foreign travelers for recreation); and (4)
within impoundments of waters defined as ‘‘waters of
the United States.’’
Our objectives are to (1) critically examine the impacts of past (pre-SWANCC) incentives and regulations pertaining to playas and their ecology, (2) postulate potential impacts of the SWANCC decision on
playa conservation efforts, and (3) suggest playa conservation approaches in light of potentially changing
regulatory conditions. To accomplish these objectives,
Haukos & Smith, PLAYA WETLAND REGULATIONS
we highlight U.S. Department of Agriculture (USDA)
farm programs and raise issues based on extensive
work in playa systems in the SHP since 1984. The
USDA material is unpublished and may soon be altered because of changes in agency policies. Further,
the views presented here are solely our own as are any
inadvertent mistakes made in interpreting implementation or enforcement of regulations associated with
playas. Unfortunately, the current lack of specific
USACE policy or criteria on the jurisdictional status
of isolated wetlands following the SWANCC decision
hinders the comprehensive assessment of the potential
impact of the decision on playas. We believe that the
presented material will serve as a foundation for future
conservation efforts of playas throughout their range.
THE EFFECTS OF ISOLATION ON THE
ECOLOGY OF PLAYAS
Compared to other isolated wetlands, relatively less
is known of basic playa ecology. Although baseline
inventories of flora and fauna are available, measurements of basic ecological rates are few (e.g., Anderson
and Smith 2002), with hypotheses addressing perceptions of total production, energy flow, nutrient cycling,
biodiversity, competition, and predation within these
ecosystems remaining to be tested. The closed watersheds and isolated environmental events (e.g., precipitation, runoff) defining playas contributes to spatial
and temporal differences in the importance of ecosystem functions even among adjacent wetlands (Hall et
al. 1995, Willig et al. 1995).
Without playas, biodiversity of the PLR would be
limited to a small number of species (Haukos and
Smith 1994). The interspersion of playas in the landscape provides islands of biodiversity exploited by a
wide range of floral and faunal species with the ability
to adapt and respond to the unpredictable playa environment. Further, the spatial and temporal environmental changes result in continually shifting plant and
animal community associations within and among playas.
Mammal and avian species are the most conspicuous, easily recognizable, and temporally persistent
components of playa fauna. At least 37 mammal species use playas for some or all of their life cycle (Haukos and Smith 1994). The variety of habitats provided
by playas supports a broad array of avian species.
There are a minimum of 185 avian species in 41 families reported in playas (Haukos and Smith 1994). Playa habitats of the PLR are used by birds for wintering,
migration, and breeding (Haukos and Smith 1994, Davis and Smith 1998, Conway 2001, Seyffert 2001). For
waterfowl and other waterbirds, playas are vital to
populations of midcontinental North America (Iverson
579
et al. 1985, Davis and Smith 1998, Conway 2001,
Haukos 2001). The spatial isolation of these wetlands
contributes to uniqueness of mammal and bird populations in playas. For example, eastern cottontail rabbit
(Sylvilagus audubonii J.A. Allen) and ring-necked
pheasant (Phasianus colchicus Linnaeus) populations
form isolated populations associated with specific playas and limited interplaya movement occurs (Scribner
et al. 1989, Scribner and Warren 1990).
Recent examination of amphibian populations has
provided some evidence of the influence of isolation
on playa ecology. Thirteen amphibian species have
been reported in playas, with geographic distribution
currently documented for 11 species (Anderson and
Haukos 1997). Species composition of amphibian
communities differ among playas and within playas
across years (Anderson et al. 1999), indicating that
amphibian species may respond differently to environmental cues that are playa specific. Further, Gray
(2002) found that spatial positioning of playas in the
landscape was as important as surrounding land use as
influences on amphibian demographics. Unfortunately,
it is not known explicitly how amphibians survive dry
periods in playas.
Playas are essential for the persistence of invertebrates in the PLR. Greater than 124 aquatic invertebrate taxa (mostly insects) with a variety of life histories have been reported in playas (Anderson 1997,
Hall et al. 1999). Few taxa have been described to
species, but preliminary examination of numerous invertebrate specimens indicates a potential for a number
of previously undescribed species (J. Cokendolpher,
personal communication). Anderson (1997) found that
(1) most playa wetland invertebrates tolerated wide
ranges of physicochemical variables, indicating that
playa-specific biotic factors were responsible for the
presence or absence of a taxa and (2) many aquatic
taxa had multiple mechanisms of surviving dry periods
in playas to increase the probability of long-term persistence. The mechanisms for species persistence include (1) drought-resistant eggs or larval stages, (2)
aestivation during drought periods, (3) maturation process tied to temperature and water levels, (4) life-stages resistant to dessication, and (5) burrowing (Anderson 1997, Hall et al. 1999). Habitat persistence, a playa-specific feature related to the temporal extent of an
environmental condition that is usually related to a soil
moisture status including flooded, moist, and dry,
which determines plant composition and structure, influences invertebrate communities as species richness
and diversity increase with time (Hall et al. 1999).
More than 340 plant species have been recorded in
playas (Haukos and Smith 1997). There are no endemic plant species in playas of the PLR. Many of the
species are commonly found in other wetland and ter-
580
restrial systems, yet are similar in their ability to persist despite the potentially extended periods of environmental conditions unsuitable for establishment in
playas.
Because of the lack of interconnecting waterways,
playa-specific seed banks dictate the extant plant community during any environmental condition (Haukos
and Smith 1993). At any point-in-time, species occurrence in playas is dependent on three factors: (1) the
composition of the available seed bank (i.e., viable
seed in a position within the soil capable of germinating), (2) the environmental conditions of previous
years that dictated species presence and replenishment
of the seed bank, and (3) the environmental conditions
of the current growing season that regulates germination and seedling growth from the seed bank (Haukos
and Smith 1993). Smith and Haukos (2002) documented species-area relationships and the impact of
watershed land use on playa flora throughout the PLR,
concluding that (1) species richness and diversity of
wetland plants was related to playa area, with habitat
persistence being the main factor affecting species
richness, (2) cultivation of surrounding watersheds
corresponded to an increase of annuals and exotic species in the playa, and (3) a turnover of an average of
33% of the species occurred during growing season
with playas. Even under constant environmental conditions, species had different temporal emergence
strategies for persistence in playas (Haukos and Smith
2001).
Identification of ecological gradients of plants in
playas depends upon the scale of examination. Within
playas, plants do not distribute along an elevational
gradient (Haukos and Smith 1994), primarily because
the playa basin is flat. As expected, a plant community
gradient was found when examining the playa and its
watershed when the transition from upland to wetland
resulted in a change in the plant community (Hoaglund
and Collins 1997). At the landscape level, we have
identified changing plant associations in response to
both growing season and rainfall gradients (D.H. Haukos and L.M. Smith, unpublished data).
All flora and fauna using playas are adapted to the
changing environmental conditions that characterize
the PLR. Stabilization of the playa environment over
time reduces diversity within individual playas, which
will reduce the biodiversity of the surrounding landscape. Because the playa ecosystem primarily depends
on resident species (e.g., plants, invertebrates, and amphibians) being able to persist despite harsh environmental conditions for initiation and maintenance of
ecological functions, any alteration of the playa hydroperiod that hinders the ability of the species to respond to changes in the environment will have drastic
effects on all species dependent on playas to exist.
WETLANDS, Volume 23, No. 3, 2003
HISTORY OF ABUSES TO PLAYAS
Physical Changes
The largest abuse to the integrity of playa ecosystems of the PLR has been, and continues to be, sedimentation (Luo et al. 1997). Sedimentation, although
preventable, has largely been a passive byproduct of
watershed cultivation and water erosion (Luo et al.
1999). In a study of playas with cropland and grassland watersheds, Luo et al. (1997) found that playas
with cultivated watersheds contained sediment volume
averaging .100% of their original hydric-soil defined
volume. This has caused a dramatic decrease in playa
hydroperiod and altered floral and faunal communities
associated with naturally functioning playas (Haukos
and Smith 1994, 1997, Smith 2003).
Playas have also been subjected to a number of
physical modifications that have altered their hydrology. The most common modification has been cultivation and pit excavation. Guthery and Bryant (1982)
found that 43% of playas, primarily the smaller wetlands, had been disked or cultivated. Results from another study indicated that 75% of playas were cropped
or disked for weed control (Guthery et al. 1982). Guthery et al. (1981) estimated that 70% of the playas
greater than 4 ha had been modified by construction
of relatively deep pits. Most of these were constructed
to concentrate irrigation water runoff (pumped from
the Ogallala Aquifer) and precipitation runoff in cultivated areas. The water could then be recirculated on
crops at a much lower cost than if pumped from the
aquifer. The presence of pits decreases the water available to the entire playa, thereby influencing hydroperiod and thus life-cycle events for the biota. In some
instances, these pits increase the area of the playa basin
that could be cultivated (Smith 2003). This type of
modification occurs in playas primarily in Nebraska.
In some grassland areas (e.g., USDA Forest Service
National Grasslands), small pits are often excavated
for livestock watering areas. Finally, many pits have
been constructed to deepen areas and maintain permanent water to raise fish bait or allow recreational
fishing.
Since the Guthery et al. (1981) study, the construction of new pits in the SHP has essentially ceased due
to changes in irrigation practices and, in part, to enforcement of wetland regulations. Because of the declining Ogallala Aquifer (Dennehy et al. 2002) and
significant increases in the cost of pumping aquifer
water, most farmers have changed from row-flood irrigation to center-pivot or under-ground drip irrigation.
These irrigation systems use less water and have little
runoff. Unfortunately, changing of irrigation systems
has not resulted in stemming the decline of the Ogallala Aquifer, with an increasingly significant number
Haukos & Smith, PLAYA WETLAND REGULATIONS
of farmers discontinuing irrigation each year because
of the inability to pump sufficient water to grow a
crop. Therefore, the need to construct new pits to concentrate water for reuse has been discontinued and use
of previously existing pits has lessened. However,
some landowners continue to maintain (i.e., remove
sediment) existing pits for purposes other than a source
of irrigation water.
Other physical modifications to playas include island construction, intentional filling, and road construction. Island construction and intentional filling
have occurred primarily in the Great Plains north of
the SHP. Islands were constructed in many playas on
the USDA Forest Service National Grasslands ostensibly to improve waterfowl nesting. In general, this has
negatively influenced playa hydrology. Also, some
small playas have been completely filled with upland
soil to expand cultivation. Impacts due to road construction have been the greatest on the SHP, where
playas occur in the greatest density and avoidance is
not economically feasible. Many playas have been
split as the result of road construction, resulting in
filled areas and permanent changes to playa hydrology.
Further, road ditches serve as a point source entry into
playas for materials contained in watershed runoff,
thus fostering accumulation of sediment and other materials.
Historically, plants in playas were grazed seasonally
by many wildlife species, including pronghorn (Antilocapra americana Ord), elk (Cervus elaphus Linnaeus), and bison (Bison bison Hamilton-Smith). Any
grazing by wildlife today is generally by small mammals, although pronghorn and deer (Odocoileus spp.)
continue to forage in grassland playas. In playas surrounded by cultivation, livestock are often maintained
exclusively within the playa basin. In grassland situations, livestock often congregate in playas because of
early growth of plants, increased plant production
compared to surrounding areas, and favorable microclimate during harsh weather. Under these situations,
playa vegetation is greatly reduced through consumption and trampling. This has been a common occurrence that negatively influences habitat.
Water Quality and Quantity
There are only a few laws or regulations addressing
water quality and quantity flowing into playas of the
PLR. Because playas are the terminus of closed watersheds, some are being used as storage for runoff
from Confined Animal Feeding Operations, urban
storm water collection sites, and evaporation basins for
municipal and industrial wastewater. Playas used for
feedlot runoff receive large loads of solids, nutrients,
oxygen-demanding organic matter, and salts (Sweeten
581
1994) that drastically change the structure and function
of playas. The state of Texas Water Code, Subtitle D
Water Quality Control, 26.048, Prohibition of Discharge to a Playa From a Concentrated Animal Feeding Operation, defines a playa as ‘‘a flat-floored, clayey bottom of an undrained basin that is located in an
arid or semi-arid part of the state, is naturally dry most
of the year, and collects runoff from rain but is subject
to rapid evaporation’’ (emphasis added). The regulation, enacted 1 September 1993, does not prohibit the
discharge from a feedlot into a playa since ‘‘a concentrated animal feeding operation authorized to discharge agricultural waste into a playa or to use a playa
as a wastewater retention facility for agricultural waste
under this chapter before the adoption of rules under
this section may continue that discharge into the playa
or use of the playa for the retention of agricultural
waste after the adoption of those rules.’’ Most feedlots
were established prior to 1993. The only requirement
in this rule is the annual testing of ground-water wells
for chlorides and nitrates.
Although most specific feedlot permits prohibit
flooding past the playa clay layer, in reality, overflows
occur frequently following heavy rainfall events (Irwin
et al. 1996). Such events have the potential to contaminate the underlying Ogallala Aquifer through recharge
(Osterkamp and Wood 1987, Zartman et al. 1996).
Feedlot operations were historically restricted to beef
cattle. Since 1990, however, there has been a dramatic
increase in other CAFOs, including dairies and swine
(Dennehy et al. 2002). These operations either directly
discharge into or occur in the watershed of a playa,
where there is a significant chance of runoff into the
playa.
Because playas naturally function in the collection
and storage of storm waters, most urban areas make
playas the focus of storm water management. Typically, playas are excavated to increase basin holding
capacity, thus creating additional capacity for surfacewater storage, creating permanent surface water in all
but the severest of droughts. By creating a permanent
water situation and eliminating the required wet-dry
cycles found in healthy playas, such modification destroys the functionality and associated biodiversity of
a playa.
The city of Lubbock, Texas defines a playa lake as
‘‘a lake with sufficient water storage capacity to contain the combined volume of its own drainage basin,
as well as the volume contributed from upstream playa
lakes for the 100-year 24-hour storm event and the
predicted water surface elevation is 0.5 feet or greater
below the lake’s natural overflow crest elevation. . . ’’
(Code of Ordinances, Chapter 21 Planning and Development, Article II. Flood Hazard Area, Division 1.,
Section 21–16). Such a definition creates a regulatory
582
situation in which playas must be excavated when urban development occurs to accommodate the increased
runoff that results with development. In 1999, the Texas State Legislature passed a law (under Local Government Code) specifically addressing the role of playas in urban storm water runoff (Title 13. Water and
Utilities, Subtitle A. Municipal Water and Utilities,
Chapter 401. Water Control by Municipalities, Section
401.001. Control of Harmful Excess of Water by Municipality With Population of 150,001 to 239,999).
This law gave ‘‘. . . municipalities with a population
of 185,000 or more the authority to regulate filling of
a playa lake within the municipality’s extraterritorial
jurisdiction as a means for the effective management
of storm water runoff to prevent: (1) harmful flooding
or (2) excess surface water.’’ Title 13 further stated
that ‘‘a regulation adopted under this section may not
(1) interfere with normal agricultural practices, including moving soil, berming for tail water reuse, plowing,
seeding, cultivating, and harvesting for the production
of food or fiber; or (2) prohibit any practice or activity
that does not decrease the water holding capacity of a
playa lake.’’
Wastewater from sewage treatment plants is frequently pumped into playas. In recent years, this practice has diminished because it is apparent that such
activities may be impacting the playa environment
(MacRae 1997). Similar to storm water storage, establishment of permanent water in playas effectively turns
the wetland into an evaporation reservoir. In 1991, the
Texas Natural Resources Conservation Commission
(TNRCC) issued a policy statement that includes ‘‘. . .
the discharge from an existing industrial or domestic
wastewater treatment facility that is authorized to use
and has used a playa lake, which does not feed into
any other surface water in the state, as a wastewater
retention facility before July 10, 1991, the effective
date of TNRCC adoption of related revisions to the
Texas Surface Water Quality Standards, 30 TAC
Chapter 307, shall not be subject to meeting such standards or other requirements for discharges to waters in
the state.’’ Further, ‘‘If groundwater contamination
from the discharge is detected, a corrective action plan
shall be developed and remediation measures shall be
required.’’ This policy applied in Lubbock, Texas,
where use of a playa for wastewater discharge was
discontinued following discovery of elevated nitrate
levels in nearby ground-water wells. The policy further
requires that wastewater discharge into a playa not authorized prior to 10 July 1991 must meet current surface water-quality standards.
In June 1998, TNRCC amended Chapter 309 Domestic Wastewater Effluent Limitation and Plant Siting, Subchapter B: Location Standards where wetlands
are defined as ‘‘those areas that are inundated or sat-
WETLANDS, Volume 23, No. 3, 2003
urated by surface water or groundwater at a frequency
and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally included swamps, marshes, bogs, playa lakes, and similar areas.’’ In Section
309.13, it states ‘‘that a wastewater treatment plant
unit may not be located in wetlands.’’ We assume that
‘‘unit’’ also includes discharge points, potentially playas. However, (h) in Section 309.13 contains the statement ‘‘For a permitted facility undergoing renewal of
an existing permit with plans and specifications approved prior to March 1, 1990, for which no design
change is requested, the facility will not be required
to comply with the requirements of this subsection’’
allowing for the continued discharge into a playa if
previously approved.
HISTORY OF PLAYA REGULATIONS
In the 1982 Army Corps of Engineers’ regulations
for implementation of Section 404 of the Clean Water
Act (33 CFR 323.2 (a3)), playas were included in the
definition of ‘‘waters of the U.S.’’ as part of the Clean
Water Act in the statement ‘‘All other waters such as
intrastate lakes, rivers, streams (including intermittent
streams), mudflats, sandflats, wetlands, sloughs, prairie
potholes, wet meadows, playa lakes, or natural ponds,
the use, degradation, or destruction of which could affect interstate or foreign commerce. . . ’’ This declaration energized the ongoing debate on the potential
for Federal government intrusion into the local and
state regulatory activities associated with playas. Despite being specifically mentioned in the definition,
few playas actually met the jurisdictional criteria at
that time as expressed by Barrows (1981:103) ‘‘For
the purposes of our regulations (i.e., USACE), some
playas would be classified as natural lakes’’ with natural lakes being ‘‘a standing body of open water that
occurs in a natural depression.’’ He further indicated
that ‘‘there is little question that a playa is a natural
depression; however, because of their ephemeral nature not all playas are natural lakes’’ and summarized
that ‘‘to have a natural lake there must be an open
body of water and that body of water must exhibit
persistency or be continuous in nature.’’ Therefore,
rather than identifying and protecting natural playas
from impacts, these conditions actually resulted in the
protection of nonfunctional playas in which the essential wetting and drying periods necessary for production, habitat development, and other ecological properties were eliminated.
Haukos & Smith, PLAYA WETLAND REGULATIONS
Changing Appreciation of Playas
A key to understanding the impacts of regulations
on playa ecosystems stems from the prevailing societal
attitudes on the value of these wetlands. For example,
Wyatt and Smith (1981:99) of the High Plains Underground Water District (HPUWD) stated ‘‘Private landowners and the state water districts agree that enhancement of playas means their modification to reduce
evaporation potential and regain cropland subjected to
periodic inundation’’ and ‘‘Private property rights
which include playa water-use rights are sacred to
landowners in the High Plains and, if challenged, all
appropriate legal remedies will be used to protect such
rights.’’ However, as ground water continues to decline, increasing the cost to pump water to grow crops,
and because commodity prices have remained low,
water district personnel and others have recognized the
potential of functioning playas as a source of income
for landowners. For example, Steiert (1998) calculated
that the gross value of wildlife-related pursuits in the
Texas High Plains was worth $182.5 million, with
hunting valued at $109.4 million. Playa-related wildlife are responsible for much of this income (Steiert
1998).
Section 404 and Playas
Prior to 1986, little attention was focused on playa
regulation. By the mid 1980s, at least 90% (our estimate) of the playas on the SHP had been anthropogenically impacted by pits and ditches, roads, storm
water excavations, collection of wastewater, dumping
of trash, livestock watering, overgrazing, and incorporation into feedlot operations. In 1986 and 1988,
respectively, the USACE (51 Fed. Reg. 41217) and
the Environmental Protection Agency (EPA: 53 Fed.
Reg. 20765) adopted the ‘‘Migratory Bird Rule’’
through expression in regulation preambles. The rule
explained that waters that are used or would be used
as habitat by migratory birds are ‘‘waters of the United
States’’ and, as such, subject to provisions of Section
404 of the Clean Water Act. This increased the potential authority of the USACE to regulate seasonally wet
playas, in addition to their previously stated existing
authority to regulate only playas containing permanent
water.
Despite use of the Migratory Bird Rule to declare
playas ‘‘waters of the United States,’’ site-by-site examination of the criteria necessary to declare a playa
jurisdictional was required because of the high degree
of variation among playas in meeting USACE criteria.
These criteria include presence of (a) hydric soils
(Randall, Lipan, and Ness clays in SHP playas), (b)
hydrophytic vegetation (see Haukos and Smith 1997),
583
and (3) surface or near surface inundation for 14 consecutive days during the growing season (hydrology)
in 50% of the years.
There have been relatively few requests for Section
404 permits from the USACE for activities involving
playas (Petrie et al. 2001; P. Hatcher, USACE, personal communication). It is difficult to assess numbers
of permit requests directly associated with a playa because of the method of record keeping, but for the Fort
Worth District of the USACE, which covers most of
the SHP (and most of the playas, .19,000), there are
an estimated 230 records of playa determinations under Section 404 since 1986 (P. Hatcher, USACE, personal communication). Prior to SWANCC, jurisdictional determinations of the vast majority of playas resulted in the wetland being considered ‘‘waters of the
United States’’; those not determined to be jurisdictional were eliminated from the designation due to extreme modification or sedimentation.
Farm Bill Provisions and Playas
In 1985, the Wetland Conservation incentive provision (Swampbuster) of the Food Security Act (Farm
Bill signed into law 23 December 1985) was established. Swampbuster, an incentive program, was designed to fill gaps of Section 404 of the Clean Water
Act on agricultural land by reducing or eliminating
Federal Farm Bill subsidies to landowners that altered
the hydrology of a jurisdictional wetland to make it
possible to grow a commodity crop. The major causes
of wetland loss, including drainage, ditching, and
channelization, were not regulated by Section 404, creating a need for Swampbuster to address these on agricultural lands. Specifically, producers are not eligible
for Farm Bill Program benefits if they make it possible
to plant an agricultural commodity on wetlands that
were converted by drainage, leveling, or anyother
means after December 23, 1985 or if they convert a
wetland for the purpose of agricultural commodity
production after November 28, 1990.
The definition of a jurisdictional wetland for Farm
Bill purposes includes (a) a predominance of hydric
soil, (b) inundation or saturation by surface or ground
water at a frequency and duration to support a prevalence of hydrophytic vegetation typically adapted for
life in saturated soil conditions, and (c) under normal
circumstances, supporting a prevalence of such vegetation. The hydrology aspect is the most frequently
debated criteria regarding jurisdictional determinations. The USDA National Food Security Act Manual
states ‘‘If the area is a playa, pothole, or pocosin [it
must be] inundated for a least 7 days or saturated for
at least 14 consecutive days during the growing season
. . . ’’
584
Evaluating the influence of Swampbuster on playas
is problematic because data are stored by USDA Farm
Services Agency (FSA) farm number, and only wetland area is recorded. Of the 60,000 farms in Texas
SHP and panhandle as of January 2002, 13,525 had
jurisdictional wetlands totaling 103,117 ha (C. Coffman, Natural Resources Conservation Service
[NRCS], personal communication). Conservatively,
dividing this area by the average playa size indicates
that 16,367 playas of the 19,339 playas in Texas were
declared jurisdictional under Swampbuster. Few determinations have been made in native grassland situations, so these playas were not included in the above
estimates. Swampbuster does not restrict activities if
the following conditions are met: (1) production is
made possible as a result of a natural conditions, such
as drought, (2) water regimes are not manipulated, (3)
woody vegetation is not removed, and (4) normal tillage practices are used that do not fill, level, or otherwise cause conversion of the wetland. Given playa hydrology, these provisions often allow playas to be cultivated.
In 1994, a Memorandum of Agreement among the
Environmental Protection Agency, U.S. Department of
Agriculture, U.S. Department of Interior, and the Department of Defense gave the NRCS initial wetland
determination authority on agricultural lands. This essentially eliminated the presence of the USACE from
the playa region for jurisdictional determinations (but
not permitting). This agreement was an attempt to alleviate some of the inconsistencies between Section
404 and Swampbuster. However, the policy of the
NRCS was that any out-of-the-ordinary requests (i.e.,
other than normal farming practices or practices covered under an USACE Nationwide Permit) were referred to the USACE for action (C. Coffman, NRCS,
personal communication).
Since the 1985 Farm Bill (Food Security Act of
1985), there have been a number of conservation programs introduced by the United States Department of
Agriculture that could apply to playas. The most successful program in the SHP and other playa areas is
the Conservation Reserve Program (CRP), with enrollment greater than 1.2 million ha in Texas alone
(Berthelsen and Smith 1995). The CRP has assisted
landowners in establishing permanent cover (grasses
and forbs) on Highly Erodible Lands and provides an
annual rental payment for the duration of the contract.
Unfortunately, during initiation of the program, many
playas were included in the program, resulting in the
wetlands being treated as uplands and planted to similar grass mixtures. Much of the original CRP area,
including playas, was planted to exotic old world bluestem (Bothriochloa ischaemum Rupr. ex Fisch. &
Mey.) or weeping lovegrass (Eragrostis curvula
WETLANDS, Volume 23, No. 3, 2003
(Schrad.) Nees) that have become established in the
landscape and are starting to invade many areas including playas (Haukos and Smith 1997).
Another important program was the Debt Cancellation Conservation Easement, which provided a voluntary opportunity for farm program participants with
loans secured by the former Farmers Home Administration (currently a part of FSA) to qualify for cancellation of a portion of their indebtedness in exchange
for a conservation or wetland easement. The U. S. Fish
and Wildlife Service (FWS) was the usual recipient of
the ‘‘inventory tracts,’’ with an option of fee transfer
and conservation easements of the properties. Currently, there are nine conservation easements and three
fee-title inventory tracts in the SHP under control of
the FWS National Wildlife Refuge System. Not all
contain a playa, but each has a wetland on the property. However, there is no active management or restoration occurring on these tracts. Regrettably, the
FWS is not interested in assuming management authority for more of these tracts because of (1) lack of
funding to fence, sign, and maintain the properties; (2)
perceived low value of small isolated tracts, and (3)
the low priority of playas in land acquisition (C. Ault,
FWS, personal communication). Through the late
1980s and mid-1990s, numerous landowners were involved in this program. However, the Texas FSA is
now screening loans to limit potential defaults. Fewer
defaults will mean fewer potential FWS management
easements (M. McCollum, FWS, personal communication).
In the 1990 reauthorization of the 1985 Food Security Act (Food, Agricultural, Conservation, and
Trade Act of 1990), the Wetland Reserve Program
(WRP; not funded until 1992, with all states eligible
starting in 1995) was established, which offers landowners payments for restoring and protecting wetlands
on their property. The 1996 Federal Agriculture Improvement and Reform Act created the Environmental
Quality Incentive Program (EQIP) and Wildlife Habitat Incentive Program (WHIP). Unfortunately, despite
interest by landowners in these programs, few successful contracts exist for tracts that include playas.
Only three landowners in Texas with playas have filed
an intention for consideration of a WRP contract as of
January 2002 (C. Coffman, NRCS, personal communication). There are several purported reasons for the
lack of successful conservation contracts associated
with playas: (1) the amount of CRP area limiting available area to be enrolled in a county—especially WRP
(i.e., CRP area caps apply to other conservation programs), (2) discouragement of application by landowners by others, (3) fear of government control or
influence on the agriculture operation, (4) lack of flexibility within the programs limiting area eligible for
Haukos & Smith, PLAYA WETLAND REGULATIONS
participation (e.g., in WRP only twice the area of hydric soil can be applied to upland area surround the
wetland), and (5) lack of local promotion by USDA.
The tremendous success of these programs in other
agriculture-dominated areas points to a high probability of success in the PLR, given appropriate support
and implementation.
State Regulations
Although most states include playas as waters of the
state, there are no state laws or regulations that are
specific to these wetlands (Petrie et al. 2001). The few
regulations existing in Texas were previously discussed. In the remaining PLR states, playas are rarely
mentioned in state regulations, and any reference to
conservation of these wetlands is vague at best. The
Division of Water Resources in the Kansas Department of Agriculture has the authority to administer water rights (surface and underground) in times of shortage to protect a water-right holder from impairment to
beneficial use of water by junior water-right holders
(Huntzinger 1998), which may impact conservation
and management of playas. In Oklahoma, ground water is deemed private property belonging to the surface
owner and subject to limited regulation, but stream
water is considered public property and subject to appropriation (Beldon 1998), and isolated standing water
is not mentioned in the regulations. Landowners are
required to use ground water for a beneficial use (including fish and wildlife propagation) and report water
use annually (Beldon 1998). However, prior to declaring fish and wildlife propagation a beneficial use,
regulators in Oklahoma successfully halted pumping
of aquifer water for use in playa management.
IMPACTS OF SWANCC ON PLAYAS
The full impact of the SWANCC decision on the
conservation of playa wetlands may not be evident for
several years, as Federal and state agencies reevaluate
their respective roles in regulation of isolated wetlands. Further, any impact would only be realized if
the previous regulations were effective in the conservation of playas. Historical application of Section 404
of the Clean Water Act had little impact on conservation of playa wetland ecology in the PLR. There is
evidence that enforcement of Section 404 in Nebraska
prevented the conversion of many Rainwater Basins
during the 1990s (LaGrange 1997). However, we believe that the SWANCC opinion has probably removed
most playas from any potential future regulation under
the Clean Water Act by elimination of the Migratory
Bird Rule, including not only Section 404, but also
Section 402 (National Pollution Discharge and Elimi-
585
nation System of the Environmental Protection Agency, which controls point source discharge into ‘‘waters
of the United States’’), and the Section 311 oil-spill
program. If pollution of a playa results in contamination of a drinking water source (e.g., Ogallala Aquifer), then Section 1431 of the Safe Drinking Water
Act, which authorizes the EPA to take emergency action to protect the source of drinking water, may be
appropriate. The remaining requirements for declaration of jurisdiction under the Clean Water Act apply
to just a few playas. Indeed, we believe that ,1% of
the playas could meet the remaining jurisdictional criteria: interstate location, adjacent or connected to navigable waters, or a significant nexus to interstate commerce (see Petrie et al. 2001 for a similar conclusion).
Therefore, some of the responsibility for regulation
of playa wetlands has fallen to individual states, which
have not previously addressed them from a wetland
perspective. As previously stated, there are no current
state regulations that consider the importance of playas
as wetlands but rather as runoff collection areas. Although usually considered ‘‘waters of the State,’’ we
found only vague language relating to playas in a review of state water statutes and a lack of consistency
among states in treatment of playas.
Most observers have indicated that as long as
Swampbuster remains in effect, isolated wetlands in
agricultural settings will remain protected. However,
there are a great number of playas that occur in grasslands and smaller tracts of land where the landowners
do not participate in any Farm Bill Program. In these
instances, the loss of Section 404 protection has eliminated any potential protection of these playas, which,
at least in grassland situations, are likely the most
functional and least impacted of the remaining playas.
Estimates of the number of playas in these situations
would be difficult given the lack of data on landowners
not enrolled in a Farm Bill Program. Further, even
with Swampbuster in effect, normal farming practices
are allowed in playas provided that hydrology has not
been altered to permit such practices. Given the ecology of playas where dry conditions are common and
necessary to the existence of the wetland function, a
high percentage of playas continue to be impacted by
cultivation during dry periods even though there is a
low probability that the crops will be harvested successfully. Creation of elevated paths for passage of
center-pivot irrigation systems is permitted provided
that water can flow between the paths (e.g., culvert
installation). Irrigation pits constructed prior to 1986,
which include nearly all pits, are allowed to be maintained (i.e., sediment removal) as long as the excavated
volume is not increased over the original excavation.
Therefore, Swampbuster, as currently interpreted and
enforced, has had little impact on playa conservation
586
at the landscape level in the PLR. We also believe that
given the SWANCC decision and some of the subsequent court interpretations of the ruling, it is unlikely
that Swampbuster, as presently written, would withstand legal challenge or administrative appeals in regard to regulation of playas.
As long as municipalities continue to view playas
only as storm water collection areas, excavation of playas in urban areas will continue. Indeed, several playas
within an area recently annexed by Lubbock, Texas
have been altered such that it is unlikely that function
and structure of the wetlands could be restored easily.
Other playas in the PLR will be affected similarly by
continued urban expansion.
Effects of the loss of Section 404 protection of playas will likely be most significant in future road construction projects, nearly all of which use Federal
funds. Because of the density of playas, it is unlikely
that any road construction project could be accomplished without impacting playas. Much of the filling
of playas is the result of road construction, either
through direct filling for the road bed or directed runoff of sediment-laden water via roadside ditches.
The only playas that will not lose Federal Clean
Water Act protection are those on the National Grasslands administered by the Forest Service (,30 playas).
Any proposed impacts to playas on these areas will
continue to be subject to public review and comment
via the preparation of either an Environmental Assessment or Environmental Impact Statement required by
the National Environmental Policy Act of 1969
(NEPA). Further, these playas will remain subject to
the Wetland and Floodplain Executive Orders, as well
as the Migratory Birds Executive Order.
FUTURE NEEDS FOR THE CONSERVATION
OF PLAYAS
The keystone ecosystems of the High Plains need
protection for biological, ecological, economic, and
social reasons. Unfortunately, compared to other wetland systems, little is known about the basic ecology
of playas, making it difficult to design and implement
scientifically-based conservation and restoration techniques. However, it is recognized that any conservation of playas must include management of surrounding watersheds (Luo et al. 1997). With the immediate
threat of wetland sedimentation, any effort to protect
a playa without management of the surrounding watershed will fail (Haukos 1994).
It is evident that playas in the PLR have received
little support in the development, implementation, and
enforcement of wetland regulation efforts from a national and regional perspective. There are other wetland systems in similar situations that have received
WETLANDS, Volume 23, No. 3, 2003
widespread support of regulations in the conservation
of wetlands. Since the 1980s, playas in the Rainwater
Basin of Nebraska have received careful scrutiny and
significant protection under previous legislation, but
how changes in interpretation of that legislation will
now affect that scrutiny is unknown.
In assessing the impact of SWANCC on playas it
should be noted that the Section 404 program is a reactionary approach to conservation and was never intended to be a planning tool in the conservation of
wetlands. Unfortunately, the lack of widespread understanding of the importance of playas has led to either superficial or no consideration in most federal
planning efforts for future conservation of wetlands.
There are two other potential federal regulatory mechanisms that should apply to playas: (1) the EPA/
TNRCC Stormwater Management Program (Section
402 permits) and (2) nonpoint source pollution Section
319 permits or activities. Successful implementation of
these programs in the PLR requires understanding of
playa ecosystems.
Assuming that Swampbuster and other Farm Bill
provisions remain intact in the future, there is a need
for fundamental changes in NRCS and FSA program
policies to ensure that playas become a priority for
conservation. These changes must be made both in
policy and implementation. Scoring systems for competitive conservation funding must be changed to (1)
reflect the importance of playas and (2) place the relatively small playas on equal footing with wetlands of
other regions. On a more basic level, the primary contact of most private landowners seeking opportunities
for playa conservation is the local county NRCS and
FSA offices. Frequently, landowners are uninformed
on USDA conservation programs or even discouraged
from applying for WRP, WHIP, EQIP, and other potential conservation opportunities (e.g., FWS’s Partners for Fish and Wildlife Program, Texas Parks and
Wildlife Department’s Landowner Incentive Program),
in spite of the high success rate of conservation funding for landowners who continue to pursue conservation opportunities. Leadership within the NRCS should
emphasize to their field personnel the value of playas
to the economy, culture, and biodiversity so that field
personnel might encourage the conservation of playas
through all possible avenues. The recently enacted
2002 Farm Bill ‘‘The Farm Security and Rural Investment Act of 2002’’ provides significant increases
in conservation funding. We recommend that conservation and restoration of playas be a priority during
development and implementation of new policies and
regulations associated with this legislation. Further,
because the greatest threat to playas is sedimentation,
we urge implementation of conservation measures that
Haukos & Smith, PLAYA WETLAND REGULATIONS
address farming practices that reduce or eliminate water erosion of playa watersheds
Moreover, misconceptions about prairie wetlands
have hampered legislation and conservation. For example, Petrie et al. (2001:iii) stated that ‘‘in general,
isolated wetlands play a minor role in meeting the
needs of waterfowl areas that are important for migration and wintering.’’ This statement is contrary to existing data and biases objective consideration of the
value of playas to migratory bird populations. Prairie
wetlands, including playas, are critical to the health of
midcontinent waterfowl populations during migration
and wintering (Haukos and Smith 1994, Haukos 2001,
Smith 2003). The creation of the Playa Lakes Joint
Venture (PLJV) and other prairie joint ventures under
the North American Waterfowl Management Plan recognized this fact. Although the PLJV has no regulatory
authority, the five member states must, either jointly
or independently, propose state regulations that ensure
the continued existence of playas and the valuable
functions associated with these wetlands. Examples of
states with regulations that address isolated wetlands
include Minnesota, Wisconsin, and Oregon. Enacted
regulations should go beyond just recognizing that playas exist and are ‘‘waters of the state’’ to emphasize
or recognize the multiplicity of playa functions. An
example of such an opportunity is the state-wide water
planning in Texas required by the 1997 Senate Bill 1,
which divided the state into 16 regional water planning
areas with the task of completing a regional water plan
by January 2001. In the Llano Estacado Regional Water Management Plan, which included the Southern
High Plains (Region O), playas were recognized as an
important component of the landscape, the focal point
for water recharged to the Ogallala Aquifer, and vital
wildlife habitat (Llano Estacado Regional Water Planning Group 2001). In addition, Nebraska Title 117
does recognize playas as waters of the state and provides protection for them, but the state currently does
not have a permitting system to administer the regulation.
Criteria for jurisdictional status of playas include the
identification of a hydric soil, hydrophytic plants, and
hydrology sufficient to create these soils and grow
these plants. Confirmation of hydrophytic plants and
hydrology criteria has always been difficult in playas
because of the dynamic and unpredictable hydroperiod. For example, a playa may be dry for a year or
more, with no evidence of hydrophytic plants, yet
upon filling rapidly develop wetland characteristics
that are easily recognizable. This difficulty has been
the center of the jurisdictional debate, resulting in recognition that the most consistent criteria for wetland
determination is the presence of a hydric soil—typically Randall clay and occasionally Lipan or Ness
587
clays. Future jurisdictional determinations or redeterminations centering on the presence of hydric soil may
become difficult as accumulating sediment obscures
the hydric soil. Indeed, the NRCS in Texas is attempting to reclassify playa soils and, in many instances, is
solely sampling the accumulated sediments, which
have no hydric characteristics. This results in the loss
of the main criteria for declaring a playa jurisdictional.
Therefore, it is likely that the numbers of jurisdictional
playas under Swampbuster will decrease in the future
as this work continues. We urge the NRCS to reconsider such an approach to reclassifying playa soil, recognize that accumulation of sediment sufficient to conceal the hydric soil is not natural and should not be
used as a factor in wetland determinations Further, we
encourage onsite evaluation of potential hydric characteristics in the original soil rather than recently accumulated sediment or relying on a soils map when
making future wetland determinations.
Previously, emphasis in the conservation of playas
was on assisting private landowners with management
of the wetlands within a typical agricultural operation.
It was thought that because of the unpredictable environment, large number, and small size of playas it
would be best to spread the limited amount of conservation funding across the region and not spend limited
resources on the public purchase of individual wetlands. Although a few playas have been either purchased or placed under permanent conservation easement since the inception of the PLJV, we believe that
a concentrated effort should be placed on the purchase
and permanent protection of selected playas that represent the least altered condition. We believe that the
conspicuous decline in functioning playas during the
past 15 years due to sedimentation, development, invasion of exotic species, declining above- and belowground water quantity and quality, and other impacts
must be offset by permanent protection of functioning
playas. Further, we also recommend that one or more
Wetland Management Districts (WMD), similar to
successful efforts for prairie pothole and Rainwater
Basin wetland systems, should be established in the
PLR. Further, this effort should be led by the U.S. Fish
and Wildlife Service with cooperation from the states
of the PLR. An exceptional opportunity to establish
these districts was presented by the Debt Reduction
Conservation Easements; unfortunately, as previously
discussed, this opportunity was not capitalized upon.
Given that Migratory Bird Stamps are purchased
throughout the region, it seems reasonable to invest
some of these funds (Migratory Bird Conservation
Fund) in the purchase of playas as part of a WMD.
Finally, the key to future conservation of playas is
educational efforts to promote understanding and appreciation of playas. Although acknowledged from a
588
WETLANDS, Volume 23, No. 3, 2003
national perspective, far too often, playas are dismissed as barren wastelands on a local and regional
scale. To ensure that playas continue to function and
maintain their vital role in the High Plains ecosystem,
it is imperative that local citizens recognize their value.
We have found that environmental activities focusing
on playas are readily accepted by children. It is our
belief that if the next generation embraces the values
of playas, then conservation efforts will be more successful than those being currently attempted.
CONCLUSIONS
From an ecological perspective, federal wetland regulations have had little impact on the conservation of
playa wetlands. It is recognized that discussion of the
potential of impacts of these regulations on playas and
private landowners has, to some degree, raised awareness of playas. Unfortunately, awareness has not been
coupled with an understanding of the critical roles of
playas in the continued existence of biodiversity (including humans) of the PLR. Despite the existence of
these regulations, functional playas continue to disappear at a considerable rate. Unless fundamental
changes are made in the implementation of existing
incentives or future regulations, conservation of playas
will remain a low priority. Regrettably, the lack of
baseline ecological data from unaltered playas makes
it difficult to document and monitor loss of playa function accurately. Further, because of the variation
among playas, biodiversity in the PLR is not related
to species richness of individual playas, but rather the
cumulative richness associated with playas across the
landscape. Therefore, because of the extensive alteration of playas and their associated watersheds, we
may never completely understand the role of playas in
the disappearing prairie ecosystems.
ACKNOWLEDGMENTS
We thank a number of individuals that contributed
to the composition of this paper either through discussions or reviewing the manuscript: C. Coffman, S.
Cooper, J. Cornely, J. Haskins, P. Hatcher, J. Hughes,
W. Johnson, T. LaGrange, L. Nymeyer, M. O’Melia,
J. Ray, J. Stiert, J. Thomas, and G. Valentine. L. M.
Smith was supported by the Caesar Kleberg Foundation for Wildlife Conservation. This is paper T-9–948
of the College of Agricultural Sciences and Natural
Resources, Texas Tech University.
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Manuscript received 23 August 2002; revisions received 9 December 2002; accepted 27 May 2003.