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USGS2007

Streamflow trends in Wisconsin's driftless area

Trends in streamflow characteristics were analyzed for streams in southwestern Wisconsin's Driftless Area by using data at selected gaging stations. The analyses indicate that annual low flows have increased significantly, whereas annual flood peaks have decreased. The same trends were not observed for forested areas of northern Wisconsin. Streamflow trends for other streams in southeastern Wisconsin draining predominantly agricultural land were similar to trends for Driftless Area streams for annual low flows. The causes for the trends are not well understood nor are the effects. Trends in annual precipitation do not explain the observed trends in streamflow. Other studies have found that erosion rates decreased significantly in the Driftless Area, and have attributed this reduction to a change of agricultural practices, which increase infiltration, decrease flood peaks, and increase low flows.Trends in streamflow characteristics were analyzed for streams in southwestern Wisconsin's Driftless Area by using data at selected gaging stations. The analyses indicate that annual low flows have increased significantly, whereas annual flood peaks have decreased. The same trends were not observed for forested areas of northern Wisconsin. Streamflow trends for other streams in southeastern Wisconsin draining predominantly agricultural land were similar to trends for Driftless Area streams for annual low flows. The causes for the trends are not well understood nor are the effects. Trends in annual precipitation do not explain the observed trends in streamflow. Other studies have found that erosion rates decreased significantly in the Driftless Area, and have attributed this reduction to a change of agricultural practices, which increase infiltration, decrease flood peaks, and increase low flows.

Water Resources Bulletin↗

USGS2007

Factors affecting herbicide yields in the Chesapeake Bay watershed, June 1994

Median concentrations and instantaneous yields of alachlor, metolachlor, atrazine, cyanazine, and simazine were generally highest at sites in the Lower Susquehanna River Basin and in agricultural subbasins. Instantaneous herbicide yields are related to land use, hydrogeologic setting, streamflow yield, and agricultural row cropping practices. The significance of these relations may be affected by the interdependence of the factors. The percentage of basin area planted in corn is the most influential factor in the prediction of herbicide yield. Instantaneous yields of all five herbicides measured in June 1994 related poorly to averaged 199094 herbicide use. Annually averaged herbicide-use data are too general to use as a predictor for short-term herbicide yields. An evaluation of factors affecting herbicide yields could be refined with more-current land use and land cover information and a more accurate estimate of the percentage of basin area planted in corn. Factors related to herbicide yields can be used to predict herbicide yields in other basins within the Chesapeake Bay watershed and to develop an estimate of herbicide loads to Chesapeake Bay.Median concentrations and instantaneous yields of alachlor, metolachlor, atrazine, cyanazine, and simazine were generally highest at sites in the Lower Susquehanna River Basin and in agricultural subbasins. Instantaneous herbicide yields are related to land use, hydrogeologic setting, streamflow yield, and agricultural row cropping practices. The significance of these relations may be affected by the interdependence of the factors. The percentage of basin area planted in corn is the most influential factor in the prediction of herbicide yield. Instantaneous yields of all five herbicides measured in June 1994 related poorly to averaged 1990-94 herbicide use. Annually averaged herbicide-use data are too general to use as a predictor for short-term herbicide yields. An evaluation of factors affecting herbicide yields could be refined with more-current land use and land cover information and a more accurate estimate of the percentage of basin area planted in corn. Factors related to herbicide yields can be used to predict herbicide yields in other basins within the Chesapeake Bay watershed and to develop an estimate of herbicide loads to Chesapeake Bay.

Water Resources Bulletin↗

USGS2007

Factors affecting pesticide occurrence and transport in a large Midwestern river basin

Several factors affect the occurrence and transport of pesticides in surface waters of the 29,400 km2 White River Basin in Indiana. A relationship was found between pesticide use and the average annual concentration of that pesticide in the White River, although this relationship varies for different classes of pesticides. About one percent of the mass applied of each of the commonly used agricultural herbicides was transported from the basin via the White River. Peak pesticide concentrations were typically highest in late spring or early summer and were associated with periods of runoff following application. Concentrations of diazinon were higher in an urban basin than in two agricultural basins, corresponding to the common use of this insecticide on lawns and gardens in urban areas. Concentrations of atrazine, a corn herbicide widely used in the White River Basin, were higher in an agricultural basin with permeable, well-drained soils, than in an agricultural basin with less permeable, more poorly drained soils. Although use of butylate and cyanazine was comparable in the White River Basin between 1992 and 1994, concentrations in the White River of butylate, which is incorporated into soil, were substantially less than for cyanazine, which is typically applied to the soil surface.

Indiana↗

USGS2014

Assessing the potential effects of fungicides on nontarget gut fungi (trichomycetes) and their associated larval black fly hosts

Fungicides are moderately hydrophobic and have been detected in water and sediment, particularly in agricultural watersheds, but typically are not included in routine water quality monitoring efforts. This is despite their widespread use and frequent application to combat fungal pathogens. Although the efficacy of these compounds on fungal pathogens is well documented, little is known about their effects on nontarget fungi. This pilot study, a field survey in southwestern Idaho from April to December 2010 on four streams with varying pesticide inputs (two agricultural and two reference sites), was conducted to assess nontarget impact of fungicides on gut fungi, or trichomycetes. Tissues of larval black flies (Diptera: Simuliidae), hosts of gut fungi, were analyzed for pesticide accumulation. Fungicides were detected in hosts from streams within agricultural watersheds but were not detected in hosts from reference streams. Gut fungi from agricultural sites exhibited decreased percent infestation, density and sporulation within the gut, and black fly tissues had elevated pesticide concentrations. Differences observed between the sites demonstrate a potential effect on this symbiotic system. Future research is needed to parse out the details of the complex biotic and abiotic relationships; however, these preliminary results indicate that impacts to nontarget organisms could have far-reaching consequences within aquatic ecosystems.

Journal of the American Water Resources Associatio↗

USGS2015

Calculating crop water requirement satisfaction in the West Africa Sahel with remotely sensed soil moisture

The Soil Moisture Active Passive (SMAP) mission will provide soil moisture data with unprecedented accuracy, resolution, and coverage, enabling models to better track agricultural drought and estimate yields. In turn, this information can be used to shape policy related to food and water from commodity markets to humanitarian relief efforts. New data alone, however, do not translate to improvements in drought and yield forecasts. New tools will be needed to transform SMAP data into agriculturally meaningful products. The objective of this study is to evaluate the possibility and efficiency of replacing the rainfall-derived soil moisture component of a crop water stress index with SMAP data. The approach is demonstrated with 0.1°-resolution, ~10-day microwave soil moisture from the European Space Agency and simulated soil moisture from the Famine Early Warning Systems Network Land Data Assimilation System. Over a West Africa domain, the approach is evaluated by comparing the different soil moisture estimates and their resulting Water Requirement Satisfaction Index values from 2000 to 2010. This study highlights how the ensemble of indices performs during wet versus dry years, over different land-cover types, and the correlation with national-level millet yields. The new approach is a feasible and useful way to quantitatively assess how satellite-derived rainfall and soil moisture track agricultural water deficits. Given the importance of soil moisture in many applications, ranging from agriculture to public health to fire, this study should inspire other modeling communities to reformulate existing tools to take advantage of SMAP data.

Journal of Hydrometeorology↗

USGS2009

Remote sensing of global croplands for food security: Way forward

This book opens a new pathway for global mapping that is focused on a specific land use theme, such as irrigated or rain-fed croplands and classes within these themes. Since croplands use most of the water consumed by humans, specific knowledge of irrigated and rain-fed croplands will be critical for precise estimates of water use. At present and in the coming decades, irrigated and rain-fed cropland area mapping is crucial for food security studies. Throughout this book, various subjects pertaining to global croplands are discussed comprehensively.

Book chapter↗

USGS2010

Exposure of nonbreeding migratory shorebirds to cholinesterase-inhibiting contaminants in the western hemisphere

Migratory shorebirds frequently forage and roost in agricultural habitats, where they may be exposed to cholinesterase-inhibiting pesticides. Exposure to organophosphorus and carbamate compounds, common anti-cholinesterases, can cause sublethal effects, even death. To evaluate exposure of migratory shorebirds to organophosphorus and carbamates, we sampled birds stopping over during migration in North America and wintering in South America. We compared plasma cholinesterase activities and body masses of individuals captured at sites with no known sources of organophosphorus or carbamates to those captured in agricultural areas where agrochemicals were recommended for control of crop pests. In South America, plasma acetylcholinesterase and butyrylcholinesterase activity in Buff-breasted Sandpipers was lower at agricultural sites than at reference sites, indicating exposure to organophosphorus and carbamates. Results of plasma cholinesterase reactivation assays and foot-wash analyses were inconclusive. A meta-analysis of six species revealed no widespread effect of agricultural chemicals on cholinesterase activity. however, four of six species were negative for acetylcholinesterase and one of six for butyrylcholinesterase, indicating negative effects of pesticides on cholinesterase activity in a subset of shorebirds. Exposure to cholinesterase inhibitors can decrease body mass, but comparisons between treatments and hemispheres suggest that agrochemicals did not affect migratory shorebirds' body mass. Our study, one of the first to estimate of shorebirds' exposure to cholinesterase-inhibiting pesticides, suggests that shorebirds are being exposed to cholinesterase- inhibiting pesticides at specific sites in the winter range but not at migratory stopover sites. future research should examine potential behavioral effects of exposure and identify other potential sitesand levels of exposure. ?? The Cooper Ornithological Society 2010.

Condor↗

USGS2021

Concentrations, loads, and associated trends of nutrients entering the Sacramento-San Joaquin Delta, California

Statistical modeling of water-quality data collected at the Sacramento River at Freeport and San Joaquin River near Vernalis, California, USA, was used to examine trends in concentrations and loads of various forms of dissolved and particulate nitrogen and phosphorus that entered the Sacramento–San Joaquin River Delta (Delta) from upstream sources between 1970 and 2019. Ammonium concentrations and loads decreased at the Sacramento River site from the mid-1970s through 1990 because of the consolidation of wastewater treatment and continuously reduced from the mid-1970s to 2019 at the San Joaquin River site. Current ammonium concentrations are mostly below 4 µM (0.056 mg N L –1 ) at both sites, a concentration above which reductions in phytoplankton productivity or changes in algal species composition may occur. The Sacramento River at Freeport site is located upstream of the Sacramento Regional County Sanitation District’s treatment facility’s discharge point; nutrient water quality there is representative of upstream sources. Inorganic nitrogen (nitrate plus ammonium) concentrations and loading differed at both sites. At the Sacramento River location, concentrations decrease in the summer agricultural season, reducing the molar ratios of nitrogen to phosphorus. In contrast, inorganic nitrogen concentrations increase in the San Joaquin River during the agricultural season as a result of irrigation runoff, increasing the molar ratio of nitrogen to phosphorus. This increase suggests a possible nitrogen limitation in the northern Delta and a phosphorus limitation in the southern Delta, as indicated by the molar ratios of bioavailable nitrogen to bioavailable phosphorus. Planned upgrades to the Sacramento Regional Wastewater Treatment Plant (SRWTP) will reduce inorganic nitrogen inputs to the northern Delta. Consequently, the supply of bioavailable nitrogen throughout the upper estuary should diminish. Source modeling of nitrogen and phosphorus identifies agriculture, atmospheric deposition, and wastewater effluent as sources of total nitrogen in the Central Valley. In contrast, geologic sources, agriculture, and wastewater discharge are the primary sources of phosphorus.

California↗

USGS2014

Assessment of bird response to the Migratory Bird Habitat Initiative using weather-surveillance radar

In response to the Deepwater Horizon oil spill in spring 2010, the Natural Resources Conservation Service implemented the Migratory Bird Habitat Initiative (MBHI) to provide temporary wetland habitat for migrating and wintering waterfowl, shorebirds, and other birds along the northern Gulf of Mexico via managed flooding of agricultural lands. We used weather-surveillance radar to conduct broad regional assessments of bird response to MBHI activities within the Mississippi Alluvial Valley and the West Gulf Coastal Plain. Across both regions, birds responded positively to MBHI management by exhibiting greater relative bird densities within sites relative to pre-management conditions in prior years and relative to surrounding non-flooded agricultural lands. Bird density at MBHI sites was generally greatest during winter for both regions. Unusually high flooding in the years prior to implementation of the MBHI confounded detection of overall changes in remotely sensed soil wetness across sites. The magnitude of bird response at MBHI sites compared to prior years and to non-flooded agricultural lands was generally related to the surrounding landscape context: proximity to areas of high bird density, amount of forested wetlands, emergent marsh, non-flooded agriculture, or permanent open water. However, these relationships varied in strength and direction between regions and seasons, a finding which we attribute to differences in seasonal bird composition and broad regional differences in landscape configuration and composition. We detected greater increases in relative bird use at sites in closer proximity to areas of high bird density during winter in both regions. Additionally, bird density was greater during winter at sites with more emergent marsh in the surrounding landscape. Thus, bird use of managed wetlands could be maximized by enrolling lands located near areas of known bird concentration and within a mosaic of existing wetlands. Weather-radar observations provide strong evidence that MBHI sites located inland from coastal wetlands impacted by the oil spill provided wetland habitat used by a variety of birds.

Gulf Of Mexico;Mississippi Alluvial Valley;West Gu↗

USGS2015

Can orchards help connect Mediterranean ecosystems? Animal movement data alter conservation priorities

As natural habitats become fragmented by human activities, animals must increasingly move through human-dominated systems, particularly agricultural landscapes. Mapping areas important for animal movement has therefore become a key part of conservation planning. Models of landscape connectivity are often parameterized using expert opinion and seldom distinguish between the risks and barriers presented by different crop types. Recent research, however, suggests different crop types, such as row crops and orchards, differ in the degree to which they facilitate or impede species movements. Like many mammalian carnivores, bobcats ( Lynx rufus ) are sensitive to fragmentation and loss of connectivity between habitat patches. We investigated how distinguishing between different agricultural land covers might change conclusions about the relative conservation importance of different land uses in a Mediterranean ecosystem. Bobcats moved relatively quickly in row crops but relatively slowly in orchards, at rates similar to those in natural habitats of woodlands and scrub. We found that parameterizing a connectivity model using empirical data on bobcat movements in agricultural lands and other land covers, instead of parameterizing the model using habitat suitability indices based on expert opinion, altered locations of predicted animal movement routes. These results emphasize that differentiating between types of agriculture can alter conservation planning outcomes.

California↗

USGS2010

Avian foods, foraging and habitat conservation in world rice fields

Worldwide, rice (Oryza sativa) agriculture typically involves seasonal flooding and soil tillage, which provides a variety of microhabitats and potential food for birds. Water management in rice fields creates conditions ranging from saturated mud flats to shallow (<30 cm) water, thereby attracting different guilds of birds. Grain not collected during harvest (i.e. waste rice) is typically the most abundant potential food of birds in rice fields, with estimates of seed mass from North America ranging from 66672 kg/ha. Although initially abundant after harvest, waste rice availability can be temporally limited. Few abundance estimates for other foods, such as vertebrate prey or forage vegetation, exist for rice fields. Outside North America, Europe and Japan, little is known about abundance and importance of any avian food in rice fields. Currently, flooding rice fields after harvest is the best known management practice to attract and benefit birds. Studies from North America indicate specific agricultural practices (e.g. burning stubble) may increase use and improve access to food resources. Evaluating and implementing management practices that are ecologically sustainable, increase food for birds and are agronomically beneficial should be global priorities to integrate rice production and avian conservation. Finally, land area devoted to rice agriculture appears to be stable in the USA, declining in China, and largely unquantified in many regions. Monitoring trends in riceland area may provide information to guide avian conservation planning in rice-agriculture ecosystems.

Waterbirds↗

USGS2011

USDA conservation program and practice effects on wetland ecosystem services in the Prairie Pothole Region

Implementation of the U.S. Department of Agriculture (USDA) Conservation Reserve Program (CRP) and Wetlands Reserve Program (WRP) has resulted in the restoration of >2 million ha of wetland and grassland habitats in the Prairie Pothole Region (PPR). Restoration of habitats through these programs provides diverse ecosystem services to society, but few investigators have evaluated the environmental benefits achieved by these programs. We describe changes in wetland processes, functions, and ecosystem services that occur when wetlands and adjacent uplands on agricultural lands are restored through Farm Bill conservation programs. At the scale of wetland catchments, projects have had positive impacts on water storage, reduction in sedimentation and nutrient loading, plant biodiversity, carbon sequestration, and wildlife habitat. However, lack of information on the geographic location of restored catchments relative to landscape‐level factors (e.g., watershed, proximity to rivers and lakes) limits interpretation of ecosystem services that operate at multiple scales such as floodwater retention, water quality improvement, and wildlife habitat suitability. Considerable opportunity exists for the USDA to incorporate important landscape factors to better target conservation practices and programs to optimize diverse ecosystem services. Restoration of hydrologic processes within wetlands (e.g., hydroperiod, water level dynamics) also requires a better understanding of the influence of conservation cover composition and structure, and management practices that occur in uplands surrounding wetlands. Although conservation programs have enhanced delivery of ecosystem services in the PPR, the use of programs to provide long‐term critical ecosystem services is uncertain because when contracts (especially CRP) expire, economic incentives may favor conversion of land to crop production, rather than reenrollment. As demands for agricultural products (food, fiber, biofuel) increase, Farm Bill conservation programs will become increasingly important to ensure provisioning of ecosystem services to society, especially in agriculturally dominated landscapes. Thus, continued development and support for conservation programs legislated through the Farm Bill will require a more comprehensive understanding of wetland ecological services to better evaluate program achievements relative to conservation goals.

Ecological Applications↗

USGS2015

Suburban groundwater quality as influenced by turfgrass and septic sources, Delmarva Peninsula, USA

Suburban land use is expanding in many parts of the United States and there is a need to better understand the potential water-quality impacts of this change. This study characterized groundwater quality in a sandy, water-table aquifer influenced by suburban development and compared the results to known patterns in water chemistry associated with natural, background conditions and agricultural effects. Samples for nutrients, major ions, and isotopes of N and O in NO 3 − were collected in 2011 beneath turfgrass from 29 shallow wells (median depth 3.7 m) and from 18 deeper wells (median depth 16.9 m) in a long-term suburban development. Nitrate (as N) concentrations in groundwater beneath turfgrass were highly variable (0.02–22.3 mg L −1 ) with a median of 2.7 mg L −1 , which is higher than natural water chemistry (>0.4 mg L −1 ; Na + –Cl − –HCO 3 − water type), but significantly lower than concentrations beneath a nearby agricultural area (median 16.9 mg L −1 ; p < .0001). Dissolved Fe concentrations in shallow suburban groundwater, attributed to chelated Fe in turfgrass fertilizers, were significantly higher ( p < .005) than concentrations from the agricultural site, although a Ca 2+ –Mg 2+ –Cl − –NO 3 − water type was dominant in both areas. A Na + –Cl − –NO 3 − water type indicated a septic-system source for nitrate in deep suburban groundwater (0.06–6.0 mg L −1 ; median 1.5 mg L −1 ). Isotopic data indicated denitrification; however, geochemical techniques were more helpful in identifying nitrate sources. Results indicate that suburban expansion into agricultural areas may significantly decrease overall nitrate concentrations in groundwater, but excessive turfgrass fertilization could result in localized contamination.

Delaware↗

USGS2004

Less waste corn, more land in soybeans, and the switch to genetically modified crops: Trends with important implications for wildlife management

American agriculture has provided abundant high-energy foods for migratory and resident wildlife populations since the onset of modern wildlife management. Responding to anecdotal evidence that corn residues are declining in cropland, we remeasured waste corn post-harvest in the Central Platte River Valley (CPRV) of Nebraska during 1997 and 1998 to compare with 1978. Post-harvest waste corn averaged 2.6% and 1.8% of yield in 1997 and 1998, respectively. After accounting for a 20% increase in yield, waste corn in 1997 and 1998 was reduced 24% and 47% from 1978. We also evaluated use of soybeans by spring-staging sandhill cranes ( Crus canadensis ) and waterfowl during spring 1998 and 1999. Despite being widely available in the CPRV, soybeans did not occur in esophageal contents of sandhill cranes ( n= 174), northern pintails ( Anas acuta , n= 139), greater white-fronted geese ( Anser albifrons , n= 198), or lesser snow geese ( Chen caerulescens , n= 208) collected with food in their esophagi. Lack of soybean consumption by cranes and waterfowl in Nebraska in early spring builds upon previously published findings, suggesting that soybeans are poorly suited for meeting nutrient needs of wildlife requiring a high-energy diet. Given evidence that high-energy food and numerous populations of seed-eating species found on farmland are declining, and the enormous potential risk to game and nongame wildlife populations if high-energy foods were to become scarce, a comprehensive research effort to study the problem appears warranted. Provisions under the Conservation Security subtitle of The Farm Security and Rural Investment Act of 2002 offer a potential mechanism to encourage producers to manage cropland in ways that would replace part of the high-energy foods that have been lost to increasing efficiency of production agriculture.

Nebraska↗

USGS2010

Landscape correlates along mourning dove call-count routes in Mississippi

Mourning dove (Zenaida macroura) call-count surveys in Mississippi, USA, suggest declining populations. We used available mourning dove call-count data to evaluate long-term mourning dove habitat relationships. Dove routes were located in the Mississippi Alluvial Valley, Deep Loess Province, Mid Coastal Plain, and Hilly Coastal Plain physiographic provinces of Mississippi. We also included routes in the Blackbelt Prairie region of Mississippi and Alabama, USA. We characterized landscape structure and composition within 1.64-km buffers around 10 selected mourning dove call-count routes during 3 time periods. Habitat classes included agriculture, forest, urban, regeneration stands, wetland, and woodlot. We used Akaike's Information Criterion to select the best candidate model. We selected a model containing percent agriculture and edge density that contained approximately 40% of the total variability in the data set. Percent agriculture was positively correlated with relative dove abundance. Interestingly, we found a negative relationship between edge density and dove abundance. Researchers should conduct future research on dove nesting patterns in Mississippi and threshold levels of edge necessary to maximize dove density. During the last 20 years, Mississippi lost more than 800,000 ha of cropland while forest cover represented largely by pine (Pinus taeda) plantations increased by more than 364,000 ha. Our results suggest observed localized declines in mourning dove abundance in Mississippi may be related to the documented conversion of agricultural lands to pine plantations.

Journal of Wildlife Management↗

USGS1992

Sources of nitrogen and phosphorous to northern San Francisco Bay

We studied nutrient sources to the Sacramento River and Suisun Bay (northern San Francisco Bay) and the influence which these sources have on the distributions of dissolved inorganic nitrogen (DIN) and dissolved reactive phosphorus (DRP) in the river and bay. We found that agricultural return flow drains and a municipal wastewater treatment plant were the largest sources of nutrients to the river during low river flow. The Sutter and Colusa agricultural drains contributed about 70% of the transport of DIN and DRP by the river above Sacramento (about 20% of the total transport by the river) between August 8 and September 26, 1985. Further downstream, the Sacramento Regional Wastewater Treatment Plant discharged DIN and DRP at rates that were roughly 70% of total DIN and DRP transport by the river at that time. Concentrations at Rio Vista on the tidal river below the Sacramento plant and at the head of the estuary were related to the reciprocals of the river flows, indicating the importance of dilution of the Sacramento waste by river flows. During very dry years, elevated DIN and DRP concentrations were observed in Suisun Bay. We used a steady-state, one-dimensional, single-compartment box model of the bay, incorporating terms for advection, exchange, and waste input, to calculate a residual rate for all processes not included in the model. We found that the residual for DIN was related to concentrations of chlorophylla (Chla). The residual for DRP was also related to Chla at high concentrations of Chla, but showed significant losses of DRP at low Chla concentrations. These losses were typically equivalent to about 80% of the wastewater input rate.

Estuaries and Coasts↗

USGS1997

Use of habitats by female northern pintails wintering in southwestern Louisiana

The breeding population of norther pintails ( Anas acuta ) in 1996 was 39% below the long-term average. Because winter habitat quality may influence subsequent breeding population size in pintails, identification of habitats used by wintering pintails and factors influencing use of habitats may be important for managing for population increase. We examined variation in diel use of habitats by radiotagged female pintails ( n = 272) in southwestern Louisiana in relation to age (imm and ad), winter (1991-92 and 1992-93), and time period within winters (pre-hunting season, first hunting season, time between split hunting seasons, second hunting season, and post-hunting season). Diurnal use of refuges was significantly greater during hunting seasons than during immediately preceding or succeeding nonhunting seasons. Consequently, we reject Tamissier's (1976) hypothesis that high diurnal use of refuges by pintails in southwestern Louisiana occurs later in winters. Time-period differences in diurnal and nocturnal use of habitats (large permanent pools, marsh, rice, fallow [idle], and other agriculture [primarily soybeans]) were not consistent between winters. Diel use of refuges or habitats did not differ in relation to female age. Females used fallow and ice agriculture extensively, particularly at night, and these habitats collectively accounted for 68-93% of nocturnal use. Differential use of habitats between winters was related to annual differences in relative abundance of rice and fallow agriculture. Proximity of refuges to agricultural areas should be an important management consideration for wintering pintails and other waterfowl.

Louisiana↗

USGS2009

Effects of Water-Management Strategies on Water Resources in the Pawcatuck River Basin, Southwestern Rhode Island and Southeastern Connecticut

The Pawcatuck River Basin in southwestern Rhode Island and southeastern Connecticut is an important high-quality water resource for domestic and public supplies, irrigation, recreation, and the aquatic ecosystem. Concerns about the effects of water withdrawals on aquatic habitat in the basin have prompted local, State, and Federal agencies to explore water-management strategies that minimize the effects of withdrawals on the aquatic habitat. As part of this process, the U.S. Geological Survey in cooperation with the U.S. Department of Agriculture Natural Resources Conservation Service and the Rhode Island Water Resources Board completed a study to assess the effects of current (2000-04) and potential water withdrawals on streamflows and groundwater levels using hydrologic simulation models developed for the basin. The major findings of the model simulations are: *Moving highly variable seasonal irrigation withdrawals from streams to groundwater wells away from streams reduces short-term fluctuations in streamflow and increases streamflow in the summer when flows are lowest. This occurs because of the inherent time lag between when water is withdrawn from the aquifer and when it affects streamflow. *A pumped well in the vicinity of small streams indicates that if withdrawals exceed available streamflow, groundwater levels drop substantially as a consequence of water lost from aquifer storage, which may reduce the time wetlands and vernal pools are saturated, affecting the animal and plant life that depend on these habitats. *The effects of pumping on water resources such as ponds, streams, and wetlands can be minimized by relocating pumping wells, implementing seasonal pumping schemes that utilize different wells and pumping rates, or both. *The effects of projected land-use change, mostly from forest to low- and medium density housing, indicate only minor changes in streamflow at the subbasin scale examined; however, at a local scale, high flows could increase, and low flows could decrease as a result of increased impervious area. In some instances, low flows could increase slightly as a result of decreased evapotranspiration from the loss of deeprooted vegetation (forest) associated with development. *In some subbasins where large areas of agricultural lands were converted to low- and medium-density housing, low flows increase because the consumptive domestic water use was projected to be less than consumptive agricultural water use. All agricultural water use was for irrigation purposes and was assumed to be lost from the basin through evapotranspiration.

Circular↗