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USGS2012

Breeding season survival and breeding incidence of female Mottled Ducks on the upper Texas gulf coast

Previous Mottled Duck ( Anas fulvigula ) studies suggested that high female breeding season survival may be caused by low nesting effort, but few breeding season estimates of survival associated with nesting effort exist on the western Gulf Coast. Here, breeding season survival (N = 40) and breeding incidence (N = 39) were estimated for female Mottled Ducks on the upper Texas coast, 2006–2008. Females were fitted with backpack radio transmitters and visually relocated every 3–4 days. Weekly survival was estimated using the Known Fate procedure of program MARK with breeding incidence estimated as the annual proportion of females observed nesting or with broods. The top-ranked survival model included a body mass covariate and held weekly female survival constant across weeks and years (S W = 0.986, SE = 0.006). When compared to survival across the entire year estimated from previous band recovery and age ratio analysis, survival rate during the breeding season did not differ. Breeding incidence was well below 100% in all years and highly variable among years (15%–63%). Breeding season survival and breeding incidence were similar to estimates obtained with implant transmitters from the mid-coast of Texas. The greatest breeding incidence for both studies occurred when drought indices indicated average environmental moisture during the breeding season. The observed combination of low breeding incidence and high breeding season survival support the hypothesis of a trade-off between the ecological cost of nesting effort and survival for Mottled Duck females. Habitat cues that trigger nesting are unknown and should be investigated.

Waterbirds↗

USGS2025

Gulf Coast Basin CORE-CM initiative final report

The Bureau of Economic Geology at the University of Texas at Austin (UT-BEG) is leading the Gulf Coast Carbon Ore, Rare Earth, and Critical Minerals (CORE-CM) Initiative to assess the potential to produce critical minerals (CMs), including rare earth elements (REEs) from coal, coal ash, and produced water related to oil and gas production, and related materials (alumina processing waste [red mud], heavy mineral sands, graphite, and zeolite) within the Gulf Coast Basin. This project represents the first phase in a long-term program and provides reconnaissance data that will be foundational for future work by assessing resources and suggesting plans to be conducted in future work and expanding stakeholder engagement. The project includes several tasks designed to identify, characterize, and assess several necessary aspects for development of CMs and REEs in the Gulf Coast Basin.

Gulf Coast basin↗

USGS2017

Earthquake-induced subsidence and burial of late holocene archaeological sites, northern Oregon coast

Fire hearths associated with prehistoric Native American occupation lie within the youngest buried lowland soil of the estuaries along the Salmon and Nehalem rivers on the northern Oregon coast. This buried soil is the result of sudden subsidence induced by a great earthquake about 300 years ago along the Cascadia subduction zone, which extends offshore along the North Pacific Coast from Vancouver Island to northern California. The earthquake 300 years ago was the latest in a series of subsidence events along the Cascadia subduction zone over the last several thousand years. Over the long term, subsidence and burial of prehistoric settlements as a result of Cascadia subduction zone earthquakes have almost certainly been an important factor contributing to the limited time depth of the archaeological record along this section of the North Pacific Coast. Copyright ?? by the Society for American Archaeology.

American Antiquity↗

USGS2022

A characterization of the deep-sea coral and sponge community along the California, Oregon, and Washington coasts using a remotely operated vehicle on the EXPRESS 2019 expedition

NOAA’s Deep-Sea Coral Research Technology Program (DSCRTP) began a 4-year funding initiative for the U.S. West Coast in 2018. The goals of the West Coast Deep-Sea Coral Initiative were to: 1) gather baseline information on DSCS in areas subject to fishing regulation changes prior to the implementation of Amendment 28; 2) improve our understanding of known DSCS bycatch “hot spots”; and 3) explore and assess DSCS resources within NOAA National Marine Sanctuaries with emphasis on areas of sanctuary resource protection and management concerns. Following the 2018 research expedition supported by NOAA Ship Bell M. Shimada (Laidig et al., 2021), a second research cruise was planned for 2019 to further survey seafloor communities in priority areas off the West Coast from Washington to California. The 2019 expedition spanned 35 days (4 Oct – 7 Nov) and was conducted from the NOAA Ship Reuben Lasker (hereafter referred to as “the ship”), beginning and ending in San Diego, CA. Surveys were conducted in deeper areas (generally 500-1200 m) in 2019 than in 2018 (limited to <650 m). These two expeditions provide data on seafloor communities and DSCS assemblages over a broad range of depths 50-1200 m.

California, Oregon, Washington↗

USGS2010

Multi-stage origin of the Coast Range ophiolite, California: Implications for the life cycle of supra-subduction zone ophiolites

The Coast Range ophiolite of California is one of the most extensive ophiolite terranes in North America, extending over 700 km from the northernmost Sacramento Valley to the southern Transverse Ranges in central California. This ophiolite, and other ophiolite remnants with similar mid-Jurassic ages, represent a major but short-lived episode of oceanic crust formation that affected much of western North America. The history of this ophiolite is important for models of the tectonic evolution of western North America during the Mesozoic, and a range of conflicting interpretations have arisen. Current petrologic, geochemical, stratigraphic, and radiometric age data all favor the interpretation that the Coast Range ophiolite formed to a large extent by rapid extension in the forearc region of a nascent subduction zone. Closer inspection of these data, however, along with detailed studies of field relationships at several locales, show that formation of the ophiolite was more complex, and requires several stages of formation. Our work shows that exposures of the Coast Range ophiolite preserve evidence for four stages of magmatic development. The first three stages represent formation of the ophiolite above a nascent subduction zone. Rocks associated with the first stage include ophiolite layered gabbros, a sheeted complex, and volcanic rocks vith arc tholeiitic or (roore rarely) low-K calc-alkaline affinities. The second stage is characterized by intrusive wehrlite-clinopyroxenite complexes, intrusive gabbros, Cr-rich diorites, and volcanic rocks with high-Ca boninitic or tholeiitic ankaramite affinities. The third stage includes diorite and quartz diorite plutons, felsic dike and sill complexes, and calc-alkaline volcanic rocks. The first three stages of ophiolite formation were terminated by the intrusion of mid-ocean ridge basalt dikes, and the eruption of mid-ocean ridge basalt or ocean-island basalt volcanic suites. We interpret this final magmatic event (MORB dikes) to represent the collision of an active spreading ridge. Subsequent reorganization of relative plate motions led to sinistral transpression, along with renewed subduction and accretion of the Franciscan Complex. The latter event resulted in uplift and exhumation of the ophiolite by the process of accretionary uplift.

California↗

USGS2005

Population status of Kittlitz's Murrelet Brachyramphus brevirostris along the southern coast of the Alaska Peninsula

The Kittlitz's murrelet ( Brachyramphus brevirostris ) is a rare seabird that nests in alpine terrain and generally forages near tidewater glaciers during the breeding season. An estimated 95% of the global population breeds in Alaska, with some unknown proportion breeding in the Russian Far East. A global population estimate using bestavailable data in the early 1990s was 20,000 individuals. However, recent survey data from two core areas (Prince William Sound and Glacier Bay) suggest that populations have declined by 75-90% during the past 10-20 years. In response to these declines, a coalition of environmental groups petitioned the USFWS in May 2001 to list the Kittlitz’s murrelet under the Endangered Species Act (ESA), and in 2004 Kittlitz’s Murrelet was declared a candidate species under the ESA. In 2005, BirdLife International classified the species as “critically endangered”. In 2002, we began a three-year project to examine population status and trend of Kittlitz’s Murrelets in areas where distribution and abundance were poorly known. Results from the 2002 field season, focused on the south coast of the Kenai Peninsula, suggested that the local population of Kittlitz’s Murrelets has declined by ca. 74% since 1986, with a current population of ca. 500 individuals. Here we present results from the 2003 field season when we surveyed Kittlitz’s Murrelets along the southern coast of the Alaska Peninsula. This is a large region that encompasses a substantial portion of the known range of the Kittlitz’s Murrelet, yet has never been surveyed rigorously for murrelets or any other non-colonial marine birds. During four weeks of surveys, we established a set of nearshore and offshore transects (over 825 linear kilometers in total) with a stratified sample design, combining random and systematically selected transects. From a total of 123 individuals seen on transects, we estimate a total population of 2265 (95% CI 1165-4405) Kittlitz’s Murrelets along the south coast of the Alaska Peninsula. For comparison, we estimate the population size of the congeneric Marbled Murrelet ( Brachyramphus marmoratus ). We discuss broad-scale murrelet habitat relationships and species comparisons, and present recommendations for management and future work. Other species of marine birds and mammals were also surveyed; summarized information is included as an appendix.

Alaska↗

USGS1993

Petroleum exploration plays and resource estimates, 1989, onshore United States; Region 1, Alaska; Region 2, Pacific Coast

This study provides brief discussions of the petroleum geology, play descriptions, and resource estimates of 220 individually assessed exploration plays in all 80 onshore geologic provinces within nine assessment regions of the continental United States in 1989; these 80 onshore provinces were assessed in connection with the determination of the Nation's estimated undiscovered resources of oil and gas. The present report covers the 25 provinces that make up Region 1, Alaska, and Region 2, Pacific Coast. It is our intention to issue Region 3, Colorado Plateau and Basin and Range, and Region 4, Rocky Mountains and Northern Great Plains, in book form as well. Regions 5 through 9 (West Texas and Eastern New Mexico, Gulf Coast, Midcontinent, Eastern Interior and Atlantic Coast) will be released individually, as Open-File Reports.

Bulletin↗

USGS2001

Discharge between San Antonio Bay and Aransas Bay, southern Gulf Coast, Texas, May-September 1999

Along the Gulf Coast of Texas, many estuaries and bays are important habitat and nurseries for aquatic life. San Antonio Bay and Aransas Bay, located about 50 and 30 miles northeast, respectively, of Corpus Christi, are two important estuarine nurseries on the southern Gulf Coast of Texas (fig. 1). According to the Texas Parks and Wildlife Department, “Almost 80 percent of the seagrasses [along the Texas Gulf Coast] are located in the Laguna Madre, an estuary that begins just south of Corpus Christi Bay and runs southward 140 miles to South Padre Island. Most of the remaining seagrasses, about 45,000 acres, are located in the heavily traveled San Antonio, Aransas and Corpus Christi Bay areas” (Shook, 2000). Population growth has led to greater demands on water supplies in Texas. The Texas Water Development Board, the Texas Parks and Wildlife Department, and the Texas Natural Resource Conservation Commission have the cooperative task of determining inflows required to maintain the ecological health of the State’s streams, rivers, bays, and estuaries. To determine these inflow requirements, the three agencies collect data and conduct studies on the need for instream flows and freshwater/ saline water inflows to Texas estuaries. To assist in the determination of freshwater inflow requirements, the U.S. Geological Survey (USGS), in cooperation with the Texas Water Development Board, conducted a hydrographic survey of discharge (flow) between San Antonio Bay and Aransas Bay during the period May–September 1999. Automated instrumentation and acoustic technology were used to maximize the amount and quality of data that were collected, while minimizing personnel requirements. This report documents the discharge measured at two sites between the bays during May–September 1999 and describes the influences of meteorologic (wind and tidal) and hydrologic (freshwater inflow) conditions on discharge between the two bays. The movement of water between the bays is controlled primarily by prevailing winds, tidal fluctuations, and freshwater inflows. An adequate understanding of mixing and physical exchange in the estuarine waters is fundamental to the assessment of the physical, chemical, and biological processes governing the aquatic system.

Texas↗

USGS2020

Water-quality comparison of the Gulf Coast aquifer system at various scales in Texas from National Water-Quality Assessment groundwater studies, 2013–15

One of the objectives of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Project is to assess groundwater quality in aquifers that are important sources of drinking water such as the coastal lowlands aquifer system, which is often referred to in Texas as the “Gulf Coast aquifer system.” The Gulf Coast aquifer system extends from Louisiana to Mexico and is a source of groundwater for several cities including Houston, Tex. The NAWQA groundwater studies in Texas in 2013–15 that assessed the Gulf Coast aquifer system included Principal Aquifer Surveys (PAS), Major Aquifer Studies (MAS), and Land Use Studies (LUS). These three study types are based on sampling networks of wells distributed in an area of interest. The PAS networks typically consist of public-supply wells that are relatively deep, the MAS networks typically consist of domestic-supply wells that are intermediate in depth, and the LUS networks typically consist of monitoring wells that are relatively shallow.

Texas↗

USGS2010

Tsunami Preparedness Along the U.S. West Coast (video)

Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the West coast of the United States, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training. This video about tsunami preparedness along the West coast distinguishes between a local tsunami and a distant event and focuses on the specific needs of each region. It offers guidelines for correct tsunami response and community preparedness from local emergency managers, first-responders, and leading experts on tsunami hazards and warnings, who have been working on ways of making the tsunami affected regions safer for the people and communities on a long-term basis. This video was produced by the US Geological Survey (USGS) in cooperation with the California Emergency Management Agency (CalEMA), Oregon Department of Geology and Mineral Industries (DOGAMI), Washington Emergency Management Division (EMD), Marin Office of Emergency Services, and Pacific Gas and Electric (PG&E).

General Information Product↗

USGS1975

Maps showing drift patterns along the north-central Texas coast, 1973-1974

An investigation of the rates and directions of drift in the northwestern Gulf of Mexico was initiated in January 1970 as part of a program to study depositional processes and sediment movement off the southern Texas coast. The first phase of that program, a study of coastal drift off south Texas, was reported by Hunter and others (1974). They reported on a three-year program of seasonal releases of both bottom and surface drifters on the south Texas shelf; this study confirmed the hypothesis that the yearly cycle of coastwise water movement is largely controlled by seasonally changing winds. They also showed complex convergences of both surface and bottom waters which shift along the coast, as well as a layered drift structure which periodically directs surface and bottom waters in opposite directions. Results of several drift studies in the northwestern Gulf of Mexico which preceded this study are summarized by Hunter and others (1974). The second phase began in July 1973, when the study was shifted to the coast off north-central Texas . This report presents the first year results in the north-central area where studies are continuing.

Texas↗

USGS2004

Mineral, Energy, and Fertilizer Resources of the North Coast of Peru: Perspective from the Santa Rita B Archaeological Site

The Santa Rita B archaeological site is in the Chao Valley, approximately 65 km southeast of Trujillo, northern Peru. Location of Santa Rita B at the emergence of several drainages from the Andean cordillera is an important factor in the almost continuous occupation of the site over the past 3,000 years. Mineral resources are abundant throughout the Andes; however, the north coast of Peru was an important center for pre-Columbian mining, metallurgy, and craftsmanship. Success of the Chavin, Moche, Chimu, and other north coast cultures is directly related to the availability and exploitation of mineral and energy resources that include: gold (?silver), as electrum, mainly from placers, and copper from local oxide and carbonate occurrences and from sulfides related to copper porphyry occurrences in the cordillera. An alloy of these three metals is referred to as tumbaga, which is the primary material for Andean metalcraft. Anthracite was used for mirrors by north coast cultures and is available near Rio Chicama, Rio Santa, and east of Santa Rita B. These outcrops are a part of the Alto Chicama, Peru's largest coalfield, which extends from Rio Chicama, in the north, for 200 km southward to Rio Santa. Charcoal from the algorrobo tree and llama dung are considered to be the common pre-Columbian energy sources for cooking and metalwork; however, availability and the higher heat content of anthracite indicate that it was used in metallurgical applications. Bitumen is available from petroleum seeps near Talara, north of the study area, and may have been used as glue or as cement. Hematite, goethite, limonite, and manganese oxides from clay-altered volcanic rock may have provided color and material for ceramics. Guano from the Islas Gua?apes, Chinchas, and Ballestas was used as fertilizer for cotton and other crops.

Open-File Report↗

USGS2007

National assessment of shoreline change, part 4: Historical coastal cliff retreat along the California coast

Coastal cliff retreat, the landward migration of the cliff face, is a chronic problem along many rocky coastlines in the United States. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding trends and rates of coastal cliff retreat. There is also a need for a comprehensive analysis of cliff retreat that is consistent from one coastal region to another. To meet these national needs, the U.S. Geological Survey is conducting an analysis of historical coastal cliff retreat along open-ocean rocky coastlines of the conterminous United States and parts of Hawaii, Alaska, and the Great Lakes. One purpose of this work is to develop standard repeatable methods for mapping and analyzing coastal cliff retreat so that periodic updates of coastal erosion can be made nationally that are systematic and internally consistent. This report on the California Coast is an accompaniment to a report on long-term sandy shoreline change for California. This report summarizes the methods of analysis, interprets the results, and provides explanations regarding long-term rates of cliff retreat. Neither detailed background information on the National Assessment of Shoreline Change Project nor detailed descriptions of the geology and geomorphology of the California coastline are presented in this report. The reader is referred to the shoreline change report (Hapke et al., 2006) for this type of background information. Cliff retreat evaluations are based on comparing one historical cliff edge digitized from maps, with a recent cliff edge interpreted from lidar (Light Detection and Ranging) topographic surveys. The historical cliff edges are from a period ranging from 1920-1930, whereas the lidar cliff edges are from either 1998 or 2002. Long-term (~70- year) rates of retreat are calculated using the two cliff edges. The rates of retreat presented in this report represent conditions from the 1930s to 1998, and are not intended for predicting future cliff edge positions or rates of retreat. Due to the geomorphology of much of California's rocky coast (high-relief, steep slopes with no defined cliff edge) as well as to gaps in both the historical maps and lidar data, we were able to derive two cliff edges and therefore calculate cliff retreat rates for a total of 353 km. The average rate of coastal cliff retreat for the State of California was -0.3±0.2 m/yr, based on rates averaged from 17,653 individual transects measured throughout all areas of California's rocky coastline. The average amount of cliff retreat was 17.7 m over the 70-year time period of our analysis. Retreat rates were generally lowest in Southern California where coastal engineering projects have greatly altered the natural coastal system. California permits shoreline stabilization structures where homes, buildings or other community infrastructure are imminently threatened by erosion. While seawalls and/or riprap revetments have been constructed in all three sections of California, a larger proportion of the Southern California coast has been protected by engineering works, due, in part, to the larger population pressures in this area.

California↗

USGS2010

The national assessment of shoreline change: A GIS compilation of vector shorelines and associated shoreline change data for the New England and Mid-Atlantic Coasts

Sandy ocean beaches are a popular recreational destination, often surrounded by communities containing valuable real estate. Development is on the rise despite the fact that coastal infrastructure is subjected to flooding and erosion. As a result, there is an increased demand for accurate information regarding past and present shoreline changes. The U.S. Geological Survey's National Assessment of Shoreline Change Project has compiled a comprehensive database of digital vector shorelines and shoreline-change rates for the New England and Mid-Atlantic Coasts. There is currently no widely accepted standard for analyzing shoreline change. Existing measurement and rate-calculation methods vary from study to study and preclude combining results into statewide or regional assessments. The impetus behind the National Assessment project was to develop a standardized method that is consistent from coast to coast for measuring changes in shoreline position. The goal was to facilitate the process of periodically and systematically updating the results in an internally consistent manner.

Open-File Report↗

USGS2011

Map of debris flows caused by rainfall during 1996 in parts of the Reedsport and Deer Head Point quadrangles, Douglas County, southern Coast Range, Oregon

This 1:12,000-scale map shows an inventory of debris flows caused by rainfall during 1996 in a 94.4 km 2 area in the southern Coast Range of Oregon. This map and associated digital data are part of a larger U.S. Geological Survey study of debris flows in the southern Coast Range. Available evidence indicates that the flows were triggered by a rain storm that occurred between November 17 and 19. The closest rain gage in the Coast Range (Goodwin Peak) recorded 245 mm during the storm. Maximum rainfall intensity during the storm was 13.2 mm/hr on November 18. Debris flows were photogrammetrically mapped from 1:12,000-scale aerial photographs flown in May, 1997. The inventory is presented on imagery derived from LiDAR data acquired in 2008. We classified mapped debris flows into four categories based on the type of debris-flow activity: (1) discrete slide source areas, (2) predominantly erosion, (3) predominantly transport or mixed erosion and deposition, and (4) predominantly deposition. Locations of woody-debris jams are also shown on the map. The area encompassed by debris flows is 2.1 percent of the 94.4 km 2 map area.

Oregon↗

USGS2013

Application of a hydrodynamic and sediment transport model for guidance of response efforts related to the Deepwater Horizon oil spill in the Northern Gulf of Mexico along the coast of Alabama and Florida

U.S. Geological Survey (USGS) scientists have provided a model-based assessment of transport and deposition of residual Deepwater Horizon oil along the shoreline within the northern Gulf of Mexico in the form of mixtures of sand and weathered oil, known as surface residual balls (SRBs). The results of this USGS research, in combination with results from other components of the overall study, will inform operational decisionmaking. The results will provide guidance for response activities and data collection needs during future oil spills. In May 2012 the U.S. Coast Guard, acting as the Deepwater Horizon Federal on-scene coordinator, chartered an operational science advisory team to provide a science-based review of data collected and to conduct additional directed studies and sampling. The goal was to characterize typical shoreline profiles and morphology in the northern Gulf of Mexico to identify likely sources of residual oil and to evaluate mechanisms whereby reoiling phenomena may be occurring (for example, burial and exhumation and alongshore transport). A steering committee cochaired by British Petroleum Corporation (BP) and the National Oceanic and Atmospheric Administration (NOAA) is overseeing the project and includes State on-scene coordinators from four States (Alabama, Florida, Louisiana, and Mississippi), trustees of the U.S. Department of the Interior (DOI), and representatives from the U.S. Coast Guard. This report presents the results of hydrodynamic and sediment transport models and developed techniques for analyzing potential SRB movement and burial and exhumation along the coastline of Alabama and Florida. Results from these modeling efforts are being used to explain the complexity of reoiling in the nearshore environment and to broaden consideration of the different scenarios and difficulties that are being faced in identifying and removing residual oil. For instance, modeling results suggest that larger SRBs are not, under the most commonly observed low-energy wave conditions, likely to move very far alongshore. This finding suggests that SRBs from one source location may not (outside of storm conditions) be redistributed to other up or down coast locations. This information can guide operational response decisions. In addition, because SRBs are less mobile compared with sand, they are likely to become buried and unburied under normal sand transport processes thereby lengthening the time SRBs may take to move onshore. The rate of onshore movement was not specifically addressed by this study, yet the results resolve the cross-shore domain and cross-shore variations in alongshore transport that are relevant to achieving the primary objectives. Furthermore, during infrequent events (for example, winter storms and severe meteorological events such as Hurricane Isaac of August 2012), energy is shown to be sufficient to move a greater range of SRB sizes and potentially expose and break up submerged oil mats. When SRBs do move alongshore, the models indicate that there are regions that are more conducive to accumulation of SRB material than others. Accumulation can occur where there are reversals and decelerations in alongshore currents and where forces created by shear stress drops below critical thresholds to maintain or initiate SRB movement. In addition, flow and SRB mobility patterns around inlets indicate patterns in hydrodynamic forces that influence redistribution of SRBs and the surface oil that mixed with sediment to form oil mats in the first place.

Alabama;Florida↗

USGS2016

Hydrologic conditions in the South Coast aquifer, Puerto Rico, 2010–15

In 1958, the U.S. Geological Survey began documenting hydrologic conditions, including groundwater levels, groundwater withdrawals for agricultural irrigation and public water supply, and water quality, in the South Coast aquifer, Puerto Rico. This information has improved the understanding of the water resources of the region. The hydrologic data indicate that (1) groundwater levels declined as much as 40 feet in the Salinas area and 11 feet in the Guayama area during 2012–14; (2) groundwater withdrawals for agricultural irrigation increased from 6.0 to 10.5 million gallons per day, or 75 percent, from 2010 to 2012; and (3) total groundwater withdrawals decreased from 29.3 to 23.8 million gallons per day from 2010 to 2014. The quantity and quality of water in the aquifer is primarily affected by variations in aquifer recharge as a result of changing rainfall or modes of irrigation; however, the spatial patterns and magnitude of water withdrawals for all uses have a secondary impact on the quantity and quality of water in the aquifer. National Oceanic and Atmospheric Administration data from climatological stations indicate that the 30-year normal precipitation for the period 1991–2010 in the South Coastal and Southern Slopes climatological regions was about 37.74 and 61.61 inches, respectively; the 30-year moving average precipitation for the period 1985–2014 was 37.94 and 61.80 inches, respectively, for these regions. The mean annual precipitation during 2012–14 was 13 percent below the 30-year moving average for the South Coastal climatological region and 7.7 percent below for the Southern Slopes climatological region. When rainfall is below the 30-year moving average, recharge is diminished and groundwater levels decline. Annual precipitation in the South Coast aquifer, which includes a large part of the South Coastal and Southern Slopes climatological regions, was 39.42, 37.25, and 34.89 inches per year for 2012, 2013, and 2014, respectively. Water level declines reduce the thickness of freshwater in the unconfined parts of the South Coast aquifer. Additionally, the pumping-induced migration of poor-quality water from deep or seaward areas of the aquifer can contribute to reductions in the thickness of freshwater in the aquifer. The reduction in the freshwater saturated thickness of the aquifer in areas near Ponce, Juana Díaz, Salinas, and Guayama is of particular concern because the total saturated thickness of the aquifer is thinner in these areas. Total dissolved solids concentration in groundwater samples indicates a small positive trend in Ponce, Santa Isabel, Salinas, and Guayama. Diminished aquifer recharge during 2012 to 2015 and, to a lesser extent, increased groundwater withdrawals have resulted in a reduction in the freshwater saturated thickness of the aquifer. The reduction in freshwater saturated thickness of the aquifer may affect freshwater resources available for agriculture and public water supply. A prolonged time period with reduced aquifer recharge may have substantial implications for groundwater levels and fresh groundwater availability.

Puerto Rico↗

USGS2022

Spatial extent of seagrasses (Zostera marina and Ruppia maritima) along the central Pacific coast of Baja California, Mexico, 1999–2000

The seagrasses eelgrass ( Zostera marina ) and widgeongrass ( Ruppia maritima ) are prominent features of coastal lagoons along the Pacific coast of Baja California, Mexico, supporting a rich diversity of marine life. Yet little is known about their spatial distribution in this region. This is a concern because of declining trends in the abundance and distribution of seagrass in parts of northern Baja California and southern California. We used 7-band satellite imagery, 4-band digital multispectral videography, and 3-band color aerial photography to map the distribution of eelgrass and widgeongrass in six embayments along the central Pacific coast of Baja California. The total spatial extent of seagrass was estimated to be 42,697 hectares, of which about 70 percent was eelgrass. This seagrass was primarily lower in the intertidal than widgeongrass in all embayments. Eelgrass and widgeongrass composed the greatest proportion (47 percent) of the spatial extent in the two largest embayments, Lagunas Ojo de Liebre and San Ignacio, and these two embayments accounted for 85 percent of all seagrass in the study area. The native cordgrass ( Spartina foliosa ) and pickleweed ( Salicornia spp .) were the predominate vegetation cover type of marshes in the three northern and three southern embayments, respectively. The three southern embayments contained mangrove ( Rhizophora spp.) and the three northern embayments did not, thus marking the northern edge of mangroves along the Pacific coast of North America. This study establishes an embayment-wide baseline for continuing investigations and monitoring future changes in the spatial abundance of seagrasses in central Baja California.

Baja California↗