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At least 145 records · Page 8Linked to original sources
USGS2011

LANDFIRE 2001 and 2008 Refresh Geographic Area Report--Pacific Southwest

The LANDFIRE National project (LF_1.0.0) was successfully completed in 2009. The goal of LANDFIRE National was to generate consistent 2001 vintage 30 meter spatial data sets for all 50 states for fire and other natural resource applications. This report highlights results from the continuation of LANDFIRE as a program to update the spatial data layers through 2008. The focus of this phase of the program was to improve the data products and account for vegetation change across the landscape caused by wildland fire, fuel and vegetation treatments, and (or) management. In addition, changes caused by insects and disease, storms, invasive plants, and other natural or anthropogenic events were incorporated when appropriate data were available. This report describes the LANDFIRE 2001/2008 Refresh effort to update existing map layers to reflect more current conditions, focusing primarily on vegetation changes. The effort incorporated user feedback and new data, producing two comprehensive Refresh data product sets: 1. LANDFIRE 2001 Refresh (LF_1.0.5) enhanced LANDFIRE map layers by incorporating user feedback and additional data to provide a foundation to update data to 2008. It was also designed to provide users with a data set to help facilitate comparisons between 2001 and 2008 (i.e. Refresh LF_1.1.0) data sets. 2. LANDFIRE 2008 Refresh (LF_1.1.0) updated map layers to reflect vegetation changes and disturbances that occurred between 1999 and 2008. In this report, we (1) address the background and provide details pertaining to why there are two Refresh data sets, (2) explain the requirements, planning, and procedures behind the completion and delivery of the updated products for each of the data product sets, (3) show and describe results, and (4) provide case studies illustrating the performance of LANDFIRE National, LANDFIRE 2001 Refresh and LANDFIRE 2008 Refresh (LF_1.1.0) data products on some example wildland fires.

Report↗
USGS2014

LANDFIRE 2001 and 2008 refresh: geographic area report: Alaska

The LANDFIRE National Project (LF_1.0.0) was successfully completed in 2009. The goal of LANDFIRE National was to generate consistent 2001 vintage 30 meter spatial data sets for all 50 States for fire and other natural resource applications. This report highlights results from the continuation of LANDFIRE as a program to update the spatial data layers through 2008. The focus of this phase of the program was to improve the data products and account for vegetation change across the landscape caused by wildland fire, fuel and vegetation treatments, and management. In addition, changes caused by insects and disease, storms, invasive plants, and other natural or anthropogenic events were incorporated when data were available. This report describes the LANDFIRE 2001/2008 Refresh effort to update existing map layers to reflect more current conditions, focusing primarily on vegetation changes. The effort incorporated user feedback and new data, producing two comprehensive Refresh data product sets: 1. LANDFIRE 2001 Refresh (LF_1.0.5) enhanced LANDFIRE map layers by incorporating user feedback and additional data to provide a foundation to update data to 2008. It was also designed to provide users with a data set to help facilitate comparisons between 2001 and 2008 (i.e. Refresh LF_1.1.0) data sets. 2. LANDFIRE 2008 Refresh (LF_1.1.0) updated map layers to reflect vegetation changes and disturbances that occurred between 1999 and 2008. In this report, we (1) address the background and provide details pertaining to why there are two Refresh data sets, (2) explain the requirements, planning, and procedures behind the completion and delivery of the updated products for each of the data product sets, (3) show and describe results, and (4) provide case studies illustrating the performance of LANDFIRE National, LANDFIRE 2001 Refresh and LANDFIRE 2008 Refresh (LF_1.1.0) data products on some example wildland fires.

Report↗
USGS2015

Lakes and reservoirs—Guidelines for study design and sampling

The “National Field Manual for the Collection of Water-Quality Data” (NFM) is an online report with separately published chapters that provides the protocols and guidelines by which U.S. Geological Survey personnel obtain the data used to assess the quality of the Nation’s surface-water and groundwater resources. Chapter A10 reviews limnological principles, describes the characteristics that distinguish lakes from reservoirs, and provides guidance for developing temporal and spatial sampling strategies and data-collection approaches to be used in lake and reservoir environmental investigations. Within this chapter are references to other chapters of the NFM that provide more detailed guidelines related to specific topics and more detailed protocols for the quality assurance and assessment of the lake and reservoir data. Protocols and procedures to address and document the quality of lake and reservoir investigations are adapted from, or referenced to, the protocols and standard operating procedures contained in related chapters of this NFM. Before 2017, the U.S. Geological Survey (USGS) “National Field Manual for the Collection of Water-Quality Data” (NFM) chapters were released in the USGS Techniques of Water-Resources Investigations series. Effective in 2018, new and revised NFM chapters are being released in the USGS Techniques and Methods series; this series change does not affect the content and format of the NFM. More information is in the general introduction to the NFM (USGS Techniques and Methods, book 9, chapter A0, 2018) at https://doi.org/10.3133/tm9A0 . The authoritative current versions of NFM chapters are available in the USGS Publications Warehouse at https://pubs.er.usgs.gov . Comments, questions, and suggestions related to the NFM can be addressed to nfm-owq@usgs.gov .

Techniques and Methods↗
USGS2022

Puget Sound Spatially Referenced Regression on Watershed Attributes (SPARROW)

The United States Geological Survey (USGS) and the Washington State Department of Ecology (Ecology) are collaborating on the development of refined, seasonal load estimates of total nitrogen and total phosphorus within watersheds draining to Washington waters of the Salish Sea for the period 2005-2020. The modeling approach for this work is based on SPARROW (Spatially Referenced Regression on Watershed Attributes), a watershed modeling technique developed by the USGS. SPARROW is typically used to estimate stream loads throughout a stream network. The estimated loads will be used within the context of the Puget Sound Nutrient Source Reduction Project to evaluate the influence of watershed contributions of nutrients throughout the stream network and to marine waters. This quality assurance project plan (QAPP) contains details about the technical approach, observational data, spatial and temporal source data, limitations, and quality assurance procedures that will be employed to develop the SPARROW models so that they can be used to inform additional actions to address excess nutrients.

Washington↗
USGS1985

Procedural guide for International Gauging Stations on boundary waters between Canada and the United States of America

Since 1909, the United States of America (U.S.A.) and Canada have employed a system of monitoring stream-flow and water levels for shared waters based upon professionalism, trust and goodwill. This document has been prepared in considerable detail for use by managers and field officers at all levels of government in Canada and the United States. Its purpose is to serve as a guide in attaining uniform procedures in the designation and operation of International Gauging Stations. For special situations where these procedures do not apply, specific mention is made in appropriate sections of the guide. This guide supersedes that of November 4, 1969, and the guide entitled "The Procedural Guide for Operation of International Gauging Stations, St. Mary-Milk Rivers," dated March 12, 1979.

Open-File Report↗
USGS1995

Multichannel seismic-reflection profiling on the R/V Maurice Ewing during the Los Angeles Region Seismic Experiment (LARSE), California

This report describes the acquisition of deep-crustal multichannel seismic-reflection data in the Inner California Borderland aboard the R/V Maurice Ewing, conducted in October 1994 as part of the Los Angeles Regional Seismic Experiment (LARSE). LARSE is a cooperative study of the crustal structure of southern California involving earth scientists from the U.S. Geological Survey, Caltech, the University of Southern California, the University of California Los Angeles, and the Southern California Earthquake Center (SCEC). During LARSE, the R/V Ewing's 20- element air gun array, totaling 137.7 liters (8470 cu. in.), was used as the primary seismic source for wide-angle recording along three main onshore-offshore lines centered on the Los Angeles basin and the epicenters of the 1933 Long Beach and 1994 Northridge earthquakes. The LARSE onshore-offshore lines were each 200-250 km long, with the offshore portions being between 90 and 150 km long. The nearly 24,000 air gun signals generated by the Ewing were recorded by an array of 170 PASSCAL REFTEK recorders deployed at 2 km intervals along all three of the onshore lines and 9 ocean bottom seismometers (OBSs) deployed along two of the lines. Separate passes over the OBS-deployment lines were performed with a long air gun repetition rate (60 and 90 seconds) to minimize acoustic-wave interference from previous shots in the OBS data. The Ewing's 4.2-km, 160-channel, digital streamer was also used to record approximately 1250 km of 40-fold multichannel seismic-reflection data. To enhance the fold of the wide-angle data recorded onshore, mitigating against cultural and wind noise in the Los Angeles basin, the entire ship track was repeated at least once resulting in fewer than about 660 km of unique trackline coverage in the Inner Borderland. Portions of the seismic-reflection lines were repeated up to 6 times. A variety of other geophysical data were also continuously recorded, including 3.5 kHz bathymetry, multi-beam swath Hydrosweep bathymetry, magnetics, and gravity data. In this report, we describe the equipment and procedures used to acquire multichannel seismic-reflection and other geophysical data aboard the Ewing, provide a detailed cruise narrative, discuss the reduction of the data, and present near-trace constant offset seismic sections of the acquired profiles.

California↗
USGS2022

General guidance for custom-built structural equation models

Structural Equation Modeling (SEM) represents a quantitative methodology for specifying and evaluating causal network hypotheses. The application of SEM typically involves the use of specialized software packages that implement estimation procedures and automate model checking and the output of summary results. There are times when the specification details an investigator wishes to implement to represent their data relationships are not supported by available SEM packages. In such cases, it may be desirable to develop and evaluate SE models “by hand”, using specialized regression tools. In this paper, I demonstrate a general approach to custom-built applications of SEM. The approach illustrated can be used for a wide array of specialized applications of non-linear, multi-level, and other custom specifications in SE models.

Maine↗
USGS2025

Lower trophic level monitoring implementation plan for Barataria Basin: Protocols and programmatic management

Prior work completed by Kiskaddon et al. (2021, 2022b, 2022a) identified critical data gaps for Lower Trophic Level (LTL) organisms in Barataria Basin, Louisiana. A Monitoring and Adaptive Management (MAM) Activity Implementation Plan (MAIP) was subsequently developed to describe a MAM Activity that would address and fill these critical data gaps (hereafter termed the “LTL project”). As the lead implementing Trustee of the LTL project, the National Oceanic and Atmospheric Administration (NOAA), in collaboration with the Louisiana Trustee Implementation Group (LA TIG), is charged with implementing the LTL project (NOAA, 2022). The Water Institute (the Institute), in cooperation with federal, state, and private entities including NOAA, the U.S. Geological Survey (USGS), Louisiana State University (LSU), University of Louisiana at Lafayette (UL Lafayette), University of California (UC) Santa Cruz, and Dynamic Solutions, LLC developed this implementation plan to further detail LTL data collection in Barataria Basin that will fulfill the MAIP. This monitoring implementation plan describes procedures and protocols critical for data collection and project management.

Louisiana↗
USGS2011

Monitoring of urban subsidence with SAR interferometric point target analysis: A case study in Suzhou, China

Ground subsidence, mainly caused by over exploitation of groundwater and other underground resources, such as oil, gas and coal, occurs in many cities in China. The annual direct loss associated with subsidence across the country is estimated to exceed 100 million US dollar. Interferometric SAR (InSAR) is a powerful tool to map ground deformation at an unprecedented level of spatial detail. It has been widely used to investigate the deformation resulting from earthquakes, volcanoes and subsidence. Repeat-pass InSAR, however, may fail due to impacts of spatial decorrelation, temporal decorrelation and heterogeneous refractivity of atmosphere. In urban areas, a large amount of natural stable radar reflectors exists, such as buildings and engineering structures, at which radar signals can remain coherent during a long time interval. Interferometric point target analysis (IPTA) technique, also known as persistent scatterers (PS) InSAR is based on these reflectors. It overcomes the shortfalls in conventional InSAR. This paper presents a procedure for urban subsidence monitoring with IPTA. Calculation of linear deformation rate and height residual, and the non-linear deformation estimate, respectively, are discussed in detail. Especially, the former is highlighted by a novel and easily implemented 2-dimensional spatial search algorithm. Practically useful solutions that can significantly improve the robustness of IPTA, are recommended. Finally, the proposed procedure is applied to mapping the ground subsidence in Suzhou city, Jiangsu province, China. Thirty-four ERS-1/2 SAR scenes are analyzed, and the deformation information over 38,881 point targets between 1992 and 2000 are generated. The IPTA-derived deformation estimates correspond well with leveling measurements, demonstrating the potential of the proposed subsidence monitoring procedure based on IPTA technique. Two shortcomings of the IPTA-based procedure, e.g., the requirement of large number of SAR images and assumed linear plus non-linear deformation model, are discussed as the topics of further research.

Jaingsu Province↗
USGS1991

A method for the concentration of fine-grained rutile (TiO2) from sediment and sedimentary rocks by chemical leaching

Quaternary marine sediment in the Gulf of Maine basins contains 0.7 to 1.0 wt percent TiO 2 (determined by X-ray fluorescence spectrometry). Most of this TiO 2 exists in the form of silt-size rutile crystals that are visible by using the petrographic microscope with transmitted light (Valentine and Commeau, 1990). The identification of rutile was confirmed by using a scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS) system. To quantify the amount of TiO 2 in the sediment contributed by rutile and its polymorphs, anatase and brookite, it was necessary to eliminate as many of the other minerals as possible, especially titanium-bearing minerals such as ilmenite, ilmenomagnetite, biotite, hornblende, oyroxene, and sphene. We accomplished this by developing a method of chemical dissolution that removed the bulk of the raw material and left the TiO 2 minerals intact. Many methods using acids and bases have been developed over the years to dissolve rocks, minerals, and sediments for chemical analysis or to concentrate specific minerals (Dolcater et al., 1970; Church, 1971; Campbell, 1973, and the references cited therein). The method developed by Raman and Jackson (1965) to concentrate rutile and anatase in soils and sediments requires digesting the sample in concentrated hydrofluoric acid (HF) for 24 hours. However, Campbell (1973) found that digestion in HF for more than 2 hours results in a loss of anatase. The method of Dolcater et al. (1970) for concentrating titanium as a free oxide requires the use of hydrofluotitanic acid (H 2 TiF 6 ), which is difficult to find on the commercial market. The acid can be prepared by the reaction of concentrated HF (48%) with an excess of TiO 2 , but the procedure requires 36 hours to complete and should be attempted with caution because it is highly exothermic. Jackson (1979) provides a detailed method for digesting soils, but many of the recommended pretreatment steps employ sodium compounds such as sodium bicarbonate (NaHCO 3 ), sodium citrate (Na 3 C 6 H 5 O 7 -2H 2 O), and sodium dithionate (Na 2 S 2 O 4 ), which are used for the removal of calcium carbonate, iron oxides, and phosphates. In combining the methods of Dolcater and Jackson, sodium compounds must be thoroughly washed from the sample because they form sodium fluotitanate (Na 2 TiF 6 ) in the presence of hydrofluotitanic acid (Fig. 1K). French and Adams (1973) described an inexpensive method for decomposing silicates by HF digestion in polypropylene containers. Their technique was effective for a wide variety of rock types. However, it did not address the problem caused by the precipitation of insoluble fluorides, nor did it outline a procedure to concentrate any residue that remained. As no one method gave the results we required, we modified procedures described in the literature and developed a process that removes 96 to 98 wt percent of the raw sample material. The residue is composed of rutile and minor amounts of micro- and cryptocrystalline TiO 2 (Fig. 1A-J), barite (Fig. 1L), elemental carbon (coal), and insoluble fluorides (Fig. 1J). The fluorides precipitate during the decomposition of siliceous material in hydrofluoric acid (e.g., MgF 2 and MgAlF 5 -2.7H 2 O; Lanmyhr and Kringstad, 1966). Most of the sample analyzed by the method described were marine muds collected from the Gulf of Maine (Valentine and Commeau, 1990). The silt and clay fraction (up to 99 wt% of the sediment) is composed of clay minerals (chiefly illite-mica and chlorite), silt-size quartz and feldspar, and small crystals (2-12 um) of rutile and hematite. The bulk sediment samples contained an average of 2 to 3 wt percent CaCO 3 . Tiher samples analyzed include red and gray Carboniferous and Triassic sandstones and siltstones exposed around the Bay of Fundy region and Paleozoic sandstones, siltstones, and shales from northern Maine and New Brunswick. These rocks are probable sources for the fine-grained rutile found in the Gulf of Maine.

Economic Geology↗
USGS2012

Updates to watershed modeling in the Potholes Reservoir basin, Washington-a supplement to Scientific Investigation Report 2009-5081

A previous collaborative effort between the U.S. Geological Survey and the Bureau of Reclamation resulted in a watershed model for four watersheds that discharge into Potholes Reservoir, Washington. Since the model was constructed, two new meteorological sites have been established that provide more reliable real-time information. The Bureau of Reclamation was interested in incorporating this new information into the existing watershed model developed in 2009, and adding measured snowpack information to update simulated results and to improve forecasts of runoff. This report includes descriptions of procedures to aid a user in making model runs, including a description of the Object User Interface for the watershed model with details on specific keystrokes to generate model runs for the contributing basins. A new real-time, data-gathering computer program automates the creation of the model input files and includes the new meteorological sites. The 2009 watershed model was updated with the new sites and validated by comparing simulated results to measured data. As in the previous study, the updated model (2012 model) does a poor job of simulating individual storms, but a reasonably good job of simulating seasonal runoff volumes. At three streamflow-gaging stations, the January 1 to June 30 retrospective forecasts of runoff volume for years 2010 and 2011 were within 40 percent of the measured runoff volume for five of the six comparisons, ranging from -39.4 to 60.3 percent difference. A procedure for collecting measured snowpack data and using the data in the watershed model for forecast model runs, based on the Ensemble Streamflow Prediction method, is described, with an example that uses 2004 snow-survey data.

Washington↗
USGS2007

The state of the art in raptor electrocution research: A global review

We systematically reviewed the raptor electrocution literature to evaluate study designs and methods used in raptor electrocution research, mitigation, and monitoring, emphasizing original research published in English. Specifically, we wondered if three decades of effort to reduce raptor electrocutions has had positive effects. The majority of literature examined came from North America, western Europe, and South Africa. In spite of intensive and often sustained effort by industry and governments across three continents for 30 years, reductions in the incidence of electrocution have been demonstrated in only a few studies. Reliable rate estimates of electrocution mortality generally are unavailable, with some exceptions. Nearly half of 110 studies we analyzed in detail were retrospective reviews of historical mortality records, banding data, or results of necropsies on dead birds received at pathology and veterinary facilities. Among prospective studies, less than half used unbiased approaches to sampling and many did not provide enough detail to assess the sampling design used. At this time, few researchers can demonstrate the reliability of standardized retrofitting procedures or the effectiveness of monitoring techniques. Future progress in reducing raptor mortalities on power lines will benefit from properly designed studies that generate rate estimates of mortality, address biasing factors, and include predictions concerning risk and techniques to reduce risk that can be tested in the field or laboratory.

Biological Conservation↗
USGS1983

Methods for estimating peak discharge and flood boundaries of streams in Utah

Equations for estimating 2-, 5-, 10-, 25-, 50-, and 100-year peak discharges and flood depths at ungaged sites in Utah were developed using multiple-regression techniques. Ratios of 500- to 100-year values also were determined. The peak discharge equations are applicable to unregulated streams and the flood depth equations are applicable to the unregulated flow in natural stream channels. The flood depth data can be used to approximate flood prone areas. Drainage area and mean basin elevation are the two basin characteristics needed to use these equations. The standard error of estimate ranges from 38% to 74% for the 100-year peak discharge and from 23% to 33% for the 100-year flood depth. Five different flood mapping methods are described. Streams are classified into four categories as a basis for selecting a flood mapping method. Procedures for transferring flood depths obtained from the regression equations to a flood boundary map are outlined. Also, previous detailed flood mapping by government agencies and consultants is summarized to assist the user in quality control and to minimize duplication of effort. Methods are described for transferring flood frequency data from gaged to ungaged sites on the same stream. Peak discharge and flood depth frequency relations and selected basin characteristics data, updated through the 1980 water year, are tabulated for more than 300 gaging stations in Utah and adjoining states. In addition, weighted estimates of peak discharge relations based on the station data and the regression estimates are provided for each gaging station used in the regression analysis. (Author 's abstract)

Water-Resources Investigations Report↗
USGS1997

Core OL-92 from Owens Lake: Project rationale, geologic setting, drilling procedures, and summary

Several lines of evidence indicated that Owens Lake, a now-dry lake in southeast California, would probably yield a continuous and climatically informative sedimentary record. Also, the details of modern climate and runoff in the area are exceptionally well known, providing a firm basis for interpreting various types of evidence from a core in terms of past climates. Drilling was carried out in early 1992 to retrieve this record. The resulting core, OL-92, was taken from the south-central part of the lake (lat 36°22.85′ N, long 117°57.95′ W). Lake surface elevation at the drill site is 1,085 m. The core’s length is 322.86 m, recovery was ~80%, and the age of its basal sediments is ~800 ka. Study of the core has revealed lithologic, chemical, mineralogic, geophysical, and paleontologic evidence that reflects alternating periods of high- and low-volume runoff into Owens Lake. This volume presents these studies and summarizes their paleoclimatic significance.

California↗
USGS2002

Cooperative investigation of precision and accuracy in chemical analysis of silicate rocks

This is the preliminary report of the first extensive program ever organized to study the analysis of igneous rocks, a study sponsored by the United States Geological Survey, the Massachusetts Institute of Technology, and the Geophysical Laboratory of the Carnegie Institution of Washington. Large samples of two typical igneous rocks, a granite and a diabase, were carefully prepared and divided. Small samples (about 70 grams) of each were sent to 25 rock-analysis laboratories throughout the world; analyses of one or both samples were reported by 34 analysts in these laboratories. The results, which showed rather large discrepancies, are presented in histograms. The great discordance in results reflects the present unsatisfactory state of rock analysis. It is hoped that the ultimate establishment of standard samples and procedures will contribute to the improvement of quality of analyses. The two rock samples have also been thoroughly studied spectrographically and petrographically. Detailed reports of all the studies will be published.

Analytical Chemistry↗
USGS2012

GEM Basic Building Taxonomy (Version 1.0)

This report documents the development of Global Earthquake Model (GEM) Basic Building Taxonomy and it also provides version 1.0 of this Taxonomy for its immediate application within GEM Physical Risk projects. Criteria for development of the GEM Building Taxonomy required that the Taxonomy be relevant to seismic performance of different construction types; be comprehensive yet simple; be collapsible; be adhering to principles that are familiar to the range of users; and ultimately be extensible to non-buildings and other hazards. The taxonomy is organized as a series of expandable tables, which contain information pertaining to various building attributes. Each attribute describes a specific characteristic that could potentially affect the seismic performance of a building. This report describes the structure and the content of the Basic Building Taxonomy, which consists of eight basic attributes, in detail. These attributes were selected after a series of interactions/discussions with all the GEM Physical Risk Global Component project teams. In addition, we also tried to gather feedback from a number of participants outside the GEM Risk Consortium group. The Basic Taxonomy attributes discussed in this report are: material; lateral load-resisting system; roof; floor; building height; date of construction; structural irregularity, and occupancy. A future Detailed Building Taxonomy will provide more details related to certain aforementioned attributes in the Basic Building Taxonomy. As well, it will also include additional attributes that are necessary for assessing building vulnerability using analytical procedures. The report also illustrates the practical use of the proposed GEM Basic Building Taxonomy by discussing example case studies, wherein the building-specific characteristics are mapped directly using GEM Taxonomic attributes and a simple taxonomic string is constructed for that building. The building taxonomy data model is highly flexible and it can be easily incorporated within the relational database architecture. Due to its ability to represent building typologies using a shorthand form, it is also possible to use this taxonomy for non-database applications. Key terms in the taxonomy are explained in an online glossary, which provides both text and graphic descriptions for the attributes and their details.

Report↗
USGS1976

Simulation procedure for modeling transient water table and artesian stress and response

The series of computer programs described in this report were designed specifically to model the ground-water regime in sufficient detail to determine the effects of the imposition of various types of stress upon the system, and to display the results in a convenient manner during calibration and when presenting projected data. SUPERMOCK simulates the ground-water system and DATE and HYDROG aid in the display of computed data. During calibration, DATE is especially useful because it has the optional feature of comparing computed data with observed data. Although the programs can be run independently, experience dictates that for best results the three should be run as steps in the same job. English units of inches, feet, and days are used in each of the programs. The units for any parameters not given in the text are clearly specified in the instructions for input to the individual programs. (Woodard-USGS)

Open-File Report↗
USGS1998

Evaluation of chemical data from selected sites in the Surface-Water Ambient Monitoring Program (SWAMP) in Florida

A cooperative study between the Florida Department of Environmental Protection (FDEP) and the U.S. Geological Survey was conducted to assess the integrity of selected water-quality data collected at 150 sites in the FDEP Surface-Water Ambient Monitoring Program (SWAMP) in Florida. The assessment included determining the consistency of the water-quality data collected statewide, including commonality of monitoring procedures and analytes, screening of the gross validity of a chemical analysis, and quality assurance and quality control (QA/QC) procedures. Four tests were used to screen data at selected SWAMP sites to estimate the gross validity of selected chemical data: (1) the ratio of dissolved solids (in milligrams per liter) to specific conductance (in microsiemens per centimeter); (2) the ratio of total cations (in milliequivalents per liter) multiplied by 100 to specific conductance (in microsiemens per centimeter); (3) the ratio of total anions (in milliequivalents per liter) multiplied by 100 to specific conductance (in microsiemens per centimeter); and (4) the ionic charge-balance error. Although the results of the four screening tests indicate that the chemical data generally are quite reliable, the extremely small number of samples (less than 5 percent of the total number of samples) with sufficient chemical information to run the tests may not provide a representative indication of the analytical accuracy of all laboratories in the program. In addition to the four screening tests, unusually low or high values were flagged for field and laboratory pH (less than 4.0 and greater than 9.0) and specific conductance (less than 10 and greater than 10,000 microsiemens per centimeter). The numbers of flagged data were less than 1 percent of the 19,937 water samples with pH values and less than 0.6 percent of the 16,553 water samples with specific conductance values. Thirty-four agencies responded to a detailed questionnaire that was sent to more than 60 agencies involved in the collection and analysis of surface-water-quality data for SWAMP. The purpose of the survey was to evaluate quality assurance methods and consistency of methods statewide. Information was compiled and summarized on monitoring network design, data review and upload procedures, laboratory and field sampling methods, and data practices. Currently, most agencies that responded to the survey follow FDEP-approved QA/QC protocol for sampling and have quality assurance practices for recording and reporting data. Also, most agencies responded that calibration procedures were followed in the laboratory for analysis of data, but no responses were given about the specific procedures. Approximately 50 percent of the respondents indicated that laboratory analysis methods have changed over time. With so many laboratories involved in analyzing samples for SWAMP, it is difficult to compare water quality from one site to another due to different reporting conventions for chemical constituents and different analytical methods over time. Most agencies responded that calibration methods are followed in the field, but no specific details were provided. Grab samples are the most common method of collection. Other data screening procedures are necessary to further evaluate the validity of chemical data collected at SWAMP sites. High variability in the concentration of targeted constituents may signal analytical problems, but more likely changes in concentration are related to hydrologic conditions. This underscores the need for accurate measurements of discharge, lake stage, tidal stage at the time of sampling so that changes in constituent concentrations can be properly evaluated and fluxes (loads) of nutrients or metals, for example, can be calculated and compared over time.

Florida↗