Middle Rio Grande Research Articles

The future of water in a desert river basin facing climate change and competing demands: A holistic approach to water sustainability in arid and semi-arid regions

Study regionThe Middle Rio Grande (MRG), defined by the portion of the basin from Elephant Butte Reservoir in New Mexico to the confluence with the Rio Conchos in Far West Texas, U.S.A. and Northern Chihuahua, Mexico. Study focusThe future of water for the MRG and many other arid and semi-arid regions of the world is challenged by a changing climate, agricultural intensification, growing urban populations, and a segmented governance system in a transboundary setting. The core question for such settings is: how can water be managed so that competing agricultural, urban, and environmental sectors can realize a sustainable future? We synthesize results from interdisciplinary research aimed at “water futures”, considering possible, probable, and preferable outcomes from the known drivers of change in the MRG in a stakeholder participatory mode. We accomplished this by developing and evaluating scenarios using a suite of scientifically rigorous computer models, melded with the input from diverse stakeholders. New hydrological insights for the regionUnder likely scenarios without significant interventions, relatively cheap and easy to access water will be depleted in about 40 years. Interventions to mitigate this outcome will be very costly. A new approach is called for based on “adaptive cooperation” among sectors and across jurisdictions along four important themes: information sharing, water conservation, greater development and use of alternative water sources, and new limits to water allocation/withdrawals coupled with more flexibility in uses.

Water quality in three potential drought refuges in an arid-land river: assessing habitat suitability for at-risk fish species

Drought is a common disturbance in arid-land streams and rivers. The survival of aquatic species depends on access to refuge habitats where water quality remains high. Over the past century, modified flow regimes and altered watershed and instream characteristics have led to the extinction and endangerment of numerous fish species endemic to the southwestern United States. We assessed the water quality of potential drought refuges in the Middle Rio Grande (MRG), with an emphasis on suitability for the endangered Rio Grande Silvery Minnow (RGSM). We examined three types of potential drought refuges: three agricultural return drain outfalls; three isolated pools that remained during streamflow intermittency; and a reach with perennial flow below an agricultural diversion dam. All potential refuges are known to contain RGSM and other fishes. Two out of three drain outfalls, one out of three isolated pools, and three out of ten kilometers of perennially wetted stream below a dam met basic water quality criteria necessary to support RGSM populations. These findings suggest that refuge habitability is context dependent, that generalizations regarding the suitability of a specific refuge type should be avoided, and that careful assessment is required to determine if a specific location will support fish assemblages. Although some areas may contain water, they may represent ecological traps if fish are exposed to poor water quality conditions compared to other potential refuge habitats.

Use of restored floodplains by fishes of the Middle Rio Grande, New Mexico, USA

AbstractNearly 1600 ha of habitat have been restored at 300 floodplain sites of the Middle Rio Grande (MRG), New Mexico, USA, as part of a cooperative effort of the Middle Rio Grande Endangered Species Collaborative Program to conserve the endangered Rio Grande silvery minnow (RGSM). These riverside sites are designed to inundate during spring run‐off and create ephemeral habitats for other aquatic and riparian species. This study of four restored floodplain sites in May–June 2017 found that of 14 fish species captured with fyke nets, common carp (41%), red shiner (32%), RGSM (16%) and white sucker (9%) dominated total numbers. Adult RGSM included 42% gravid females, 36% ripe males and 22% spent females, suggesting that this endangered species was spawning in and near these floodplains. Larval sampling also showed that restored sites and adjacent mainstem banklines were being used as nursery habitats, where RGSM larvae dominated six and nine species with 80% and 74% of total numbers, respectively. System‐wide proportions of RGSM larvae by phase suggest that larvae leave the floodplains and move to mainstem banklines beginning as late mesolarvae and metalarvae (14–22 days post‐hatch), and most depart by the juvenile stage. Altogether, 15 fish species were encountered in restored floodplain sites in 2017, compared to 16 species reported in concurrent annual mainstem monitoring. This study and others show that most fish species of the MRG move onto restored and natural floodplains equally in spring, and many use these habitats for spawning and as larval nurseries.

Trade Relationships and Gene Flow at Pottery Mound Pueblo, New Mexico

Pottery Mound is a large Ancestral Puebloan site situated within the Middle Rio Grande (MRG) region of New Mexico. This article adds to our understanding of relationships between Pottery Mound, the Western Pueblos, and Mexico through use of biological distance analysis based on dental nonmetric traits. Extensive material and cultural influences, as well as migration events from Western Pueblos to Pottery Mound, have been proposed by several scholars, while others have highlighted parallels to Mexico, especially Paquimé. A total of 1,528 individuals from the U.S. Southwest and Mexico were used to examine relationships between Pottery Mound and these areas. We find no evidence of close biological similarity between Pottery Mound and the Western Pueblos or northern Mexico. Instead, the results indicate biological affinity between Pottery Mound and sites in the MRG region and Mogollon areas. This similarity suggests that although there is evidence for trade between Pottery Mound and other sites in the southwestern United States and Mesoamerica, trade may not have been accompanied by significant gene flow from those areas from which the trade goods originated. It is possible that neighboring regions, such as the Mogollon, served as intermediaries for trade between Pottery Mound and distant regions.

Effect of Hydrologic, Geomorphic, and Vegetative Conditions on Avian Communities in The Middle Rio Grande of New Mexico

We evaluated relationships among hydrogeomorphology, vegetation structure and composition, and avian communities among three subreaches of the San Acacia Reach of the Middle Rio Grande (MRG) River of New Mexico. The subreaches varied in degradation, with Subreach 1 being severely entrenched and hydrologically disconnected, Subreach 2 being the least impacted, and Subreach 3 being intermediately disturbed. Avian point count and habitat surveys were conducted to determine avian community structure and abundance, geomorphic feature, surface flooding, and vegetation structure and composition. Ground-nesting birds and low shrub-nesting birds were insensitive to hydrogeomorphic changes as they do not rely on native understory but can use exotic understory or woody debris. In contrast, canopy-nesting birds required native overstory; therefore, they were sensitive to hydrogeomorphic changes as native overstory species require surface floods to germinate and establish. Additionally, native overstory did not vary as expected as the moderately impacted subreach, Subreach 3, had more native overstory ($$ \overline{x} $$ = 30.04%, SE = ±4.57) than the least disturbed subreach, Subreach 2 ($$ \overline{x} $$= 11.20%, SE = ±1.96). These findings were a result of temporal asynchrony between hydrogeomorphic conditions and overstory composition. No subreach is unaltered and all have been affected by the hydrologic and geomorphic changes on the MRG.

Polycentricity of urban watershed governance: Towards a methodological approach

This paper makes an initial contribution towards building a polycentricity index to account for the governing of social–ecological systems. It develops three indices and an overall index, using an approach based on network science, to measure the extent to which actors develop ordered relationships to address scale mismatches in urban water governance. These indices are discussed with respect to the overarching system of rules governing actors’ decisions within the Middle Rio Grande (MRG) urban watershed. The analysis and discussions herein suggest that the governance of the MRG is a predominantly monocentric governing system with elements of polycentricity. They also suggest that polycentricity in governing the MRG urban water commons could primarily be about the politics of power and resource distribution as actors reconfigure their positionalities and align themselves and their interests strategically. The paper concludes with a succinct discussion about how quantitative measures of an overarching system of rules could be incorporated into future indices.

Water Governance Challenges in New Mexico's Middle Rio Grande Valley: A Resilience Assessment

Climate change presents an unprecedented challenge to traditional forms of water governance in the American Southwest. This Article centers on one watershed struggling to meet these challenges — New Mexico’s Middle Rio Grande (MRG). The MRG includes the urban environments of Albuquerque, Santa Fe, as well as surrounding small towns, and rural agricultural communities. This Article provides an overview of the MRG as a complex and dynamic social-ecological system and what challenges may arise under expected hydrologic changes. Employing concepts from resilience theory, it describes the challenges facing water governance in the MRG, placing particular emphasis on the current function and capacity of existing governance structures. After a basic overview of resilience as a paradigm for understanding the dynamics of an SES, it provides a brief overview of the current governance framework for the MRG. It then provides a description of the key social and ecological system elements and their associated interactions. Having identified the key social and ecological elements involved, we discuss possible key interactions among them, including “tipping points” — key thresholds that, if crossed, may threaten the long-term stability of the MRG. We then look at the implications of these interactions and tipping points for natural resource managers and discuss whether the current governance structures are equipped for the challenges ahead. This includes a discussion regarding the potential for and current investment in the use of adaptive management in the MRG.

Flood pulse trophic dynamics of larval fishes in a restored arid-land, river-floodplain, Middle Rio Grande, Los Lunas, New Mexico

Rio Grande water is intensively managed and regulated by international and interstate compacts, Native American treaties, local water rights, and federal, state, and local agencies. Legislation and engineering projects in the early twentieth century brought about water impoundment projects and channelization of the Rio Grande which led to the eventual loss of floodplain habitats. In particular, current water management practices in the Middle Rio Grande (MRG) have altered the natural flood regime altering the riparian community and floodplain dynamics which may be causing the demise of many fish species by altering food web processes. The Rio Grande silvery minnow (Hybognathus amarus), a federally endangered species, has been classified as an herbivore, detritivore, or carnivore. During low flow conditions H. amarus is primarily an algivore; however, during flood conditions, hydrodynamic scouring reduces or eliminates benthic algal food sources. The objective of this study was to identify and characterize food resources and trophic interactions for H. amarus on a restored floodplain during an extended flood-pulse release from reservoirs using stable isotope analyses (δ13C and δ15N) and paleolimnology techniques. Results from stable isotope ratios indicate that H. amarus obtained carbon primarily from chironomids while aquatic invertebrates (including chironomids) obtained their carbon from macrophytes. Results from the GLIMMIX procedure indicate that the range of isotopic signatures for prey items was much broader at parallel habitats (i.e. floodplain flow parallel to main stem flow) than perpendicular (i.e. floodplain flow perpendicular to main stem flow) or leeward habitats (i.e. leeward sides of island where flow was near zero) indicating a wider selection of food resources. This study suggests that increased duration of floodplain inundation in the MRG provides vital habitats for spawning, nursery, and recruitment of threatened and endangered fish species. A combination of allochthonous and autochthonous resources best describes the nutrient and energy transfers for the Los Lunas, NM restored floodplain.

DETERMINING THE INTERACTION BETWEEN THE RIO GRANDE AND RIVERSIDE DRAINS USING AN ADCP

The Middle Rio Grande (MRG), located in central New Mexico, is a river that has experienced significant anthropomorphic changes and requires extensive river management to meet all demands for water. To better understand and manage the MRG, the Upper Rio Grande Water Operations Model was developed by several government agencies; however, drain accretion rates, total seepage volumes from the river to the drain network, and salinity were unknown and represented a large data gap. In 2010, a study using an Acoustic Doppler Current Profiler was conducted to determine drain accretion rates throughout the MRG valley. The use of an Acoustic Doppler Current Profiler allowed for a multitude of measurements to be completed in a short-time span. The total yearly baseline drain accretion determined during the study was 269 630 AF, which represents about 59% of the water that is diverted annually in the MRG. The magnitude of the drain accretion was much higher than expected and represents a tangible water volume that needs to be addressed in water accounting and management decisions. The New Mexico Interstate Stream Commission is currently using the collected data to improve Upper Rio Grande Water Operations Model and results from the study will aid the Middle Rio Grande Conservancy District in improving water delivery operations. The findings of this study indicate that a complex groundwater, drain, and river water interaction is taking place near the San Acacia diversion dam with upwelling saline groundwater increasing drain water salinity to levels as high as 1703 μS. Further detailed study of groundwater and river water interactions is suggested in this area. Copyright © 2012 John Wiley & Sons, Ltd.

Riparian Forest Restoration: Conflicting Goals, Trade-Offs, and Measures of Success

Restoration projects can have varying goals, depending on the specific focus, rationale, and aims for restoration. When restoration projects use project-specific goals to define activities and gauge success without considering broader ecological context, determination of project implications and success can be confounding. We used case studies from the Middle Rio Grande (MRG), southwest USA, to demonstrate how restoration outcomes can rank inconsistently when narrowly-based goals are used. Resource managers have chosen MRG for restoration due to impacts to the natural flood regime, reduced native tree recruitment, and establishment of non-native plants. We show restoration “success” ranks differently based upon three goals: increasing biodiversity, increasing specific ecosystem functions, or restoring native communities. We monitored 12 restored and control sites for seven years. Treatments ranked higher in reducing exotic woody populations, and increasing proportions of native plants and groundwater salvage, but generally worse at removing fuels, and increasing species and habitat structural diversity. Managers cannot rely on the term “restoration” to sufficiently describe a project’s aim. Specific desired outcomes must be defined and monitored. Long-term planning should include flexibility to incorporate provisions for adaptive management to refine treatments to avoid unintended ecological consequences.

Habitat use of the Rio Grande silvery minnow (Hybognathus amarus) during a long-term flood pulse in the Middle Rio Grande, New Mexico

The Middle Rio Grande (MRG) of New Mexico has been influenced by man for over 500 years. Native Americans began diverting water to irrigate agricultural crops in the floodplain in the 14th century. The Spanish followed and increased agricultural irrigation to over 125 000 acres. Frequent flooding of the MRG valley in the 19th century led to many engineering projects in the early 20th century to control flooding. A series of impoundment dams, di- version dams, and levees were constructed. The loss of floodplain habitats throughout the MRG Valley has altered the riparian community and caused the demise of many fish species. A controlled flood pulse from Cochiti Reservoir, New Mexico was initiated in April 2005 to support the recovery of the endangered Rio Grande silvery minnow, Hybognathus amarus. This study documents habitat selection by larval fishes in a restored floodplain in the Rio Grande, NM. Larval fish light traps captured 394 larvae representing four cyp- rinid species (Pimephales promelas, H. amarus, Cyp- rinella lutrensis and Cyprinus carpio). Results for CCA indicate that Hybognathus amarus prefer shal- low, low velocity habitats. Results from Chao-Jaccard similarity index indicated that relative contribution was highest in P. promelas at 64% followed by H. amarus 33%. Results from (dis)similarity analysis re- veal that species composition between habitat orienta- tion and date was highest in H. amarus at 42% followed by P. promelas 40%. Cyprinella lutrensis and C. carpio represented 9.5 and 8.5%, respectively. A general linear model indicated that only depth and velocity were significantly different (p00.02 and p0 0.03 respectively).

Use of existing water, sediment, and tissue data to screen ecological risks to the endangered Rio Grande silvery minnow

A screening-level ecological risk assessment was applied to two extensive, but previously unanalyzed datasets from the middle Rio Grande (MRG) in New Mexico. The assessment evaluated how adverse water-quality effects from aquatic toxicants may have influenced the population decline of the endangered Rio Grande silvery minnow ( Hybognathus amarus; silvery minnow). Standardized US Environmental Protection Agency (USEPA) screening-level ecological risk assessment procedures were applied to chemicals assessed in samples collected from the MRG between 1985 and 2003. Since more chemicals have established risk-screening criteria, relative to water-quality criteria, this approach produces more complete assessments. Chemical concentrations at some locations and times were potentially sufficient to affect fish health or produce localized mortalities. Many constituents displaying the highest risks have substantial natural sources within the watershed; native species likely would have adapted to natural instream concentrations such that actual risks might be markedly less than projected by a risk screening based on generic aquatic-life criteria. Also, highest risks found for individual and combinations of contaminants were very inconsistent both within and across the sites. As such, this risk assessment does not support the conclusion that toxicants were a primary factor causing the silvery minnow population to decline in the MRG between 1985 and 2003. The assessment indicates that sediment-borne, relative to water-borne, contaminants appeared to present the greatest risks to the silvery minnow and thus should have increased focus during future assessments of potential contaminant effects in the MRG. Contaminants of greatest concern are identified. This study presents approaches to cost-effectively assess and reduce uncertainties associated with potential water quality effects, and to help direct future assessments of water quality onto those contaminants likely to produce potentially significant effects. The techniques presented and criteria compiled are suitable for aiding similar assessments in other aquatic habitats.

Predicting velocity in bendway weir eddy fields

AbstractRehabilitation of the Middle Rio Grande (MRG) in central New Mexico has become necessary because of changes in morphology resulting from the installation of dams, and because of habitat restoration considerations for the endangered Rio Grande silvery minnow (Hybognathus amarus). Bendway weirs are erosion control and channel‐stabilization structures placed transverse to the channel flow that have been increasingly used to prevent river migration while simultaneously enhancing aquatic habitat. Plans for rehabilitation along the MRG include the use of bendway weirs; however, past projects using these structures have relied on field experience and engineering judgment rather than specific design guidelines. A physical model of a reach of the MRG was constructed to develop empirical design equations for eddy velocities in bendway weir fields. Data from physical model simulations were used to develop two empirical expressions for predicting eddy velocities behind bendway weirs, along with two expressions for predicting velocities at the toe of installed weirs. These equations relate the velocity found after bendway weir installation to weir design characteristics and pre‐weir channel conditions. A designer can use the described approach to predict velocities in eddies and velocities at the toe of bendway weirs using only weir design variables and pre‐weir channel conditions, and thus avoid some of the uncertainty with weir design that previously existed. Copyright © 2009 John Wiley & Sons, Ltd.

Impact of Non‐Native Plant Removal on Lizards in Riparian Habitats in the Southwestern United States

Abstract Many natural processes in the riparian cottonwood (Populus deltoides) forest of the Middle Rio Grande (MRG) in the southwestern United States have been disrupted or altered, allowing non‐native plants such as saltcedar (Tamarix spp.) and Russian olive (Elaeagnus angustifolia) to establish. We investigated reptilian responses to restoration efforts by sampling communities of lizards at 12 study sites invaded by non‐native plants along the MRG in New Mexico for 7 years (2000–2006). Sites within three regions were randomly assigned to one of the three treatments to remove non‐native plants and woody debris, or as untreated controls. We used pitfall and funnel traps to capture, mark, and release lizards from June to September. Principal components analysis of 15 vegetation variables identified five factors that best explained variation among sites before and after removal of non‐native plants. Relative abundances for four of six common species of lizards were associated with vegetation characteristics that significantly changed after plant removal. Species were either positively associated with the more open, park‐like understory found in treated sites or negatively associated with debris heaps and thickets of non‐native plants found in untreated sites. Eastern fence lizards (Sceloporus consobrinus) and New Mexico whiptails (Aspidoscelis neomexicana) increased in relative abundance after non‐native plants were removed. Overall, removal of non‐native plants seems beneficial, or at least is non‐damaging, to lizard communities of the MRG forest. Providing information on habitat associations of lizard communities will help land managers balance management objectives with other considerations, such as providing important wildlife habitat.

Riparian ecohydrology: regulation of water flux from the ground to the atmosphere in the Middle Rio Grande, New Mexico

AbstractDuring the previous decade, the south‐western United States has faced declining water resources and escalating forest fires due to long‐term regional drought. Competing demands for water resources require a careful accounting of the basin water budget. Water lost to the atmosphere through riparian evapotranspiration (ET) is believed to rank in the top third of water budget depletions. To better manage depletions in a large river system, patterns of riparian ET must be better understood. This paper provides a general overview of the ecological, hydrological, and atmospheric issues surrounding riparian ET in the Middle Rio Grande (MRG) of New Mexico. Long‐term measurements of ET, water table depth, and micro‐meteorological conditions have been made at sites dominated by native cottonwood (Populus deltoides) forests and non‐native saltcedar (Tamarix chinensis) thickets along the MRG. Over periods longer than one week, groundwater and leaf area index (LAI) dynamics relate well with ET rates. Evapotranspiration from P. deltoides forests was unaffected by annual drought conditions in much of the MRG where the water table is maintained within 3 m of the surface. Evapotranspiration from a dense Tamarix chinensis thicket did not decline with increasing groundwater depth; instead, ET increased by 50%, from 6 mm/day to 9 mm/day, as the water table receded at nearly 7 cm/day. Leaf area index of the T. chinensis thicket, likewise, increased during groundwater decline. Leaf area index can be manipulated as well following removal of non‐native species. When T. chinensis and non‐native Russian olive (Elaeagnus angustifolia) were removed from a P. deltoides understory, water salvaged through reduced ET was 26 cm/yr in relation to ET measured at reference sites. To investigate correlates to short‐term variations in ET, stepwise multiple linear regression was used to evaluate atmospheric conditions under which ET is elevated or depressed. At the P. deltoides‐dominated sites, ET anomalies were positively correlated to net radiation (Rn) and negatively correlated to sensible heat flux (H), cross‐corridor wind speed (v), and along‐corridor wind speed (u) (r2 = 0·54). At the T. chinensis‐dominated sites, ET anomalies were positively correlated with Rn, u, the friction coefficient (u*), and vapour pressure deficit (VPD) and were negatively correlated to surface humidity scale (q*), daily high and low temperature, H, and precipitation (r2 = 0·66). Both Tamarix and Populus can transpire prodigious quantities of water when conditions are favourable. In the MRG, T. chinensis is preferentially found where summer flooding and cold air drainage occurs, and P. deltoides is preferentially located in areas with shallow groundwater within 2 m of the surface. Copyright © 2006 John Wiley & Sons, Ltd.

Effects of an experimental flood on litter dynamics in the middle rio grande riparian ecosystem

AbstractThe objectives of the study were to measure the effects of an experimental flood on : (1) leaf litter production by the riparian forest; (2) leaf decomposition; and (3) the amount of forest floor organic matter. The study area is located at Bosque del Apache National Wildlife Refuge, approximately 160 km south of Albuquerque, New Mexico. Experimental and reference study sites of about 3·1 ha were both located in cottonwood (Populus fremontii) riparian forests that had not been flooded for approximately 50 years. The experimental and control study sites were sampled for two years before flooding the experimental site. The experimental flood peaked on about 31 May, the average date of peak flow in the 100 year hydrograph for the USGS gauging station on the Rio Grande at Embudo, New Mexico. Litter fall was lower at the flood site than at the control site, whereas the rate of leaf decomposition was higher at the flood site during the period of inundation. However, the flood did not produce a measurable response in standing stock of forest floor litter. This pool of carbon may require the cumulative effects of several years of flooding to show a measurable response.