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USGS2009

Land Cover Trends in the Southern Florida Coastal Plain

This report presents an assessment of land use and land cover change in the Southern Florida Coastal Plain ecoregion for the period from 1973 to 2000. The ecoregion is one of 84 level III ecoregions defined by the Environmental Protection Agency; ecoregions have been designed to serve as a spatial framework for environmental resource management and denote areas that contain a geographically distinct assemblage of biotic and abiotic phenomena, including geology, physiography, vegetation, climate, soils, land use, wildlife, and hydrology. The Southern Florida Coastal Plain ecoregion covers an area of approximately 22,407 square kilometers [8,651 square miles] across the lower portion of the Florida peninsula, from Lake Okeechobee southward through the Florida Keys. It comprises flat plains with wet soils, marshland and swamp land cover with Everglades and palmetto prairie vegetation types.

Scientific Investigations Report↗
USGS2009

Water Withdrawals, Use, and Trends in Florida, 2005

In 2005, the total amount of water withdrawals in Florida was estimated at 18,359 million gallons per day (Mgal/d). Saline water accounted for 11,486 Mgal/d (63 percent), and freshwater accounted for 6,873 Mgal/d (37 percent). Groundwater accounted for 4,247 Mgal/d (62 percent) of freshwater withdrawals, and surface water accounted for the remaining 2,626 Mgal/d (38 percent). Surface water accounted for nearly all (99.9 percent) saline-water withdrawals. An additional 660 Mgal/d of reclaimed wastewater was used in Florida during 2005. The largest amount of freshwater was withdrawn from Palm Beach County, and the largest amount of saline water was withdrawn from Pasco County. Fresh groundwater provided drinking water (public supplied and self-supplied) for 16.19 million people (90 percent of Florida's population), and fresh surface water provided drinking water for 1.73 million people (10 percent). The majority of groundwater withdrawals (nearly 60 percent) in 2005 was obtained from the Floridan aquifer system which is present throughout the entire State. The majority of fresh surface-water withdrawals (59 percent) came from the southern Florida hydrologic unit subregion and is associated with Lake Okeechobee and the canals in the Everglades Agricultural Area of Glades, Hendry, and Palm Beach Counties, as well as the Caloosahatchee River and its tributaries in the agricultural areas of Collier, Glades, Hendry, and Lee Counties. Overall, agricultural irrigation accounted for 40 percent of the total freshwater withdrawals (ground and surface), followed by public supply with 37 percent. Public supply accounted for 52 percent of groundwater withdrawals, followed by agricultural self-supplied (31 percent), ommercial-industrial-mining self-supplied (8.5 percent), recreational irrigation and domestic self-supplied (4 percent each), and power generation (0.5 percent). Agricultural self-supplied accounted for 56 percent of fresh surface-water withdrawals, followed by power generation (20.5 percent), public supply (13 percent), recreational irrigation (6 percent), and commercial-industrial self-supplied (4.5 percent). Power generation accounted for nearly all (99.9 percent) saline-water withdrawals. Of the 17.92 million people who resided in Florida during 2005, 41 percent (7.36 million people) resided in the South Florida Water Management District (SFWMD), followed by the St. Johns River Water Management District (SJRWMD) and the Southwest Florida Water Management District (SWFWMD) with 25 percent each (4.46 and 4.44 million people, respectively), the Northwest Florida Water Management District (NWFWMD) with 7.5 percent (1.34 million people), and the Suwannee River Water Management District (SRWMD) with 1.5 percent (0.32 million people). The largest amount of freshwater withdrawals was from the SFWMD, which was one-half (50 percent) of the State's total freshwater withdrawals, followed by the SJRWMD (19 percent), SWFWMD (16 percent), NWFWMD (10 percent), and SRWMD (5 percent). Between 1950 and 2005, the population of Florida increased by 15.15 million (550 percent), and the total water withdrawals (fresh and saline) increased 15,700 Mgal/d (600 percent). More recently, total withdrawals decreased 1,790 Mgal/d (9 percent) between 2000 and 2005, but the total population increased by 1.94 million (12 percent). Between 1990 and 2005, saline-water withdrawals increased 1,120 Mgal/d (11 percent), whereas between 2000 and 2005, saline-water withdrawals decreased 470 Mgal/d (4 percent). Between 1990 and 2005, freshwater withdrawals decreased 710 Mgal/d (9 percent), whereas between 2000 and 2005, freshwater withdrawals decreased 1,320 Mgal/d (16 percent). The use of highly mineralized groundwater as a source of supply, primarily for public supply, also has increased in Florida. This water, referred as nonpotable water, increased from just less than 2 Mgal/d in 1970, to 142 Mgal/d in 2005. Nonpotable water is treated to meet drin

Scientific Investigations Report↗
USGS2009

Occurrence and Trends of Selected Chemical Constituents in Bottom Sediment, Grand Lake O' the Cherokees, Northeast Oklahoma, 1940-2008

After over 100 years of continuous activity, lead and zinc mining in the Tri-State Mining District (hereafter referred to as the TSMD) in parts of southeast Kansas, southwest Missouri, and northeast Oklahoma ended in the 1970s. The mining activity resulted in substantial historical and ongoing input of cadmium, lead, and zinc to the environment including Grand Lake O' the Cherokees (hereafter referred to as Grand Lake), a large reservoir in northeast Oklahoma. To help determine the extent and magnitude of contamination in Grand Lake, a one-year study was conducted by the U.S. Geological Survey in cooperation with the U.S. Fish and Wildlife Service. Bottom-sediment coring at five sites was used to investigate the occurrence of cadmium, lead, zinc, and other selected constituents in the bottom sediment of Grand Lake. Cadmium concentrations in the bottom sediment of Grand Lake ranged from 2.3 to 3.6 mg/kg (milligrams per kilogram) with a median of 3.5 mg/kg (5 samples). Compared to an estimated local background concentration of 0.6 mg/kg, the historical mining activity increased cadmium concentrations by about 280 to 500 percent. Lead concentrations ranged from 35 to 102 mg/kg with a median of 59 mg/kg (50 samples). Compared to an estimated local background concentration of 20 mg/kg, the historical mining activity increased lead concentrations by about 75 to 410 percent. The range in zinc concentrations was 380 to 986 mg/kg with a median of 765 mg/kg (50 samples). Compared to an estimated local background concentration of 100 mg/kg, the historical mining activity increased zinc concentrations by about 280 to 890 percent. With the exception of the most upstream coring site, the lead and zinc depositional profiles generally were similar in terms of the range in concentrations measured and the temporal pattern observed. Depositional profiles for lead and zinc indicated mid-core peaks followed by concentrations that decreased since about the 1980s. The depositional profiles reflect the complex interaction of several factors including historical mining and related activities, mine drainage, remediation, landscape stabilization, precipitation and associated runoff, and the erosion and transport of contaminated and clean sediments within the basin. Compared to sediment-quality guidelines, the Grand Lake samples had cadmium concentrations that were substantially less than the general probable-effects concentration (PEC) (4.98 mg/kg) and a TSMD-specific PEC (11.1 mg/kg). The PECs represent the concentration above which toxic biological effects are likely to occur. Likewise, all sediment samples had lead concentrations that were substantially less than the general PEC (128 mg/kg) and a TSMD-specific PEC (150 mg/kg). Zinc concentrations typically exceeded the general PEC (459 mg/kg), but were substantially less than a TSMD-specific PEC (2,083 mg/kg). Throughout the history of Grand Lake, lead and zinc concentrations in the deposited sediment did not approach or exceed the TSMD-specific PECs. As of 2008, legacy effects of mining still included the delivery of contaminated sediment to Grand Lake by the Spring and Neosho Rivers. The Neosho River, with its larger flows and less-contaminated sediment, likely dilutes the load of contaminated sediment delivered to Grand Lake by the Spring River. The information contained in this report provides a baseline of Grand Lake conditions with which to compare future conditions that may represent a response to changes in mining-related activity in the Grand Lake Basin.

Scientific Investigations Report↗
USGS2011

Status and trends of the rainbow trout population in the Lees Ferry reach of the Colorado River downstream from Glen Canyon Dam, Arizona, 1991–2009

The Lees Ferry reach of the Colorado River, a 25-kilometer segment of river located immediately downstream from Glen Canyon Dam, has contained a nonnative rainbow trout (Oncorhynchus mykiss) sport fishery since it was first stocked in 1964. The fishery has evolved over time in response to changes in dam operations and fish management. Long-term monitoring of the rainbow trout population downstream of Glen Canyon Dam is an essential component of the Glen Canyon Dam Adaptive Management Program. A standardized sampling design was implemented in 1991 and has changed several times in response to independent, external scientific-review recommendations and budget constraints. Population metrics (catch per unit effort, proportional stock density, and relative condition) were estimated from 1991 to 2009 by combining data collected at fixed sampling sites during this time period and at random sampling sites from 2002 to 2009. The validity of combining population metrics for data collected at fixed and random sites was confirmed by a one-way analysis of variance by fish-length class size. Analysis of the rainbow trout population metrics from 1991 to 2009 showed that the abundance of rainbow trout increased from 1991 to 1997, following implementation of a more steady flow regime, but declined from about 2000 to 2007. Abundance in 2008 and 2009 was high compared to previous years, which was likely the result of increased early survival caused by improved habitat conditions following the 2008 high-flow experiment at Glen Canyon Dam. Proportional stock density declined between 1991 and 2006, reflecting increased natural reproduction and large numbers of small fish in samples. Since 2001, the proportional stock density has been relatively stable. Relative condition varied with size class of rainbow trout but has been relatively stable since 1991 for fish smaller than 152 millimeters (mm), except for a substantial decrease in 2009. Relative condition was more variable for larger size classes, and substantial decreases were observed for the 152-304-mm size class in 2009 and 305-405-mm size class in 2008 that persisted into 2009.

Arizona↗
USGS2011

Water withdrawals, wastewater discharge, and water consumption in the Apalachicola-Chattahoochee-Flint River Basin, 2005, and water-use trends, 1970-2005

The Apalachicola-Chattahoochee-Flint (ACF) River Basin covers about 20,500 square miles that drains parts of Alabama, Florida, and Georgia. The basin extends from its headwaters northern Georgia to the Gulf of Mexico. Population in the basin was estimated to be 3.7 million in 2005, an increase of about 41 percent from the 1990 population of 2.6 million. In 2005, slightly more than 721,000 acres of crops were irrigated within the basin. In 2005, the total amount of water withdrawn in the ACF River Basin was about 1,990 million gallons per day (Mgal/d). Of this, surface water accounted for 1,591 Mgal/d (80 percent) and groundwater accounted for 399 Mgal/d (20 percent). Surface water was the primary water source of withdrawals in the northern and central parts of the basin, and groundwater was the primary source in the southern part. The largest surface-water withdrawals was from Cobb County, Georgia (410 Mgal/d, mostly from the Chattahoochee River and Lake Alatoona), and the largest groundwater withdrawals was from Dougherty County, Georgia (38 Mgal/d, mostly from the Upper Floridan aquifer system). Thermoelectric power generation accounted for the largest water withdrawals in 2005 at 788 Mgal/d (40 percent). Most of these withdrawals were used for once-through cooling, and nearly all water used for this purpose was returned to its source. Public supply accounted for 609 Mgal/d (30 percent) of total withdrawals in 2005, followed by agricultural self-supplied (including crop, golf course irrigation, and livestock) at 365 Mgal/d (18 percent), commercial-industrial self-supplied (including mining) at 191 Mgal/d (10 percent), and domestic self-supplied at 37 Mgal/d (2 percent). Public-supply withdrawals were lowest during January, February, and March (about 500 Mgal/d), and highest during September (about 700 Mgal/d). As the population of the ACF River Basin increased by 1.7 million (83 percent) in the 35 years between 1970 and 2005, total withdrawals in the basin increased by more than 515 Mgal/d (35 percent). Of this increase, surface-water accounted for 206 Mgal/d (15 percent) and groundwater accounted for 309 Mgal/d (350 percent). Since 1980, total water withdrawals have generally declined, except in 2000 when they peaked because of below-average rainfall. In 2000, an estimated 49 percent of the water withdrawn for public supply in the basin was consumed, and the remaining 51 percent was returned to the hydrologic system through wastewater treatment systems. In 2005, an estimated 38 percent was consumed and 62 percent was returned to the hydrologic system. This contrast between water withdrawals and wastewater discharges for these years was caused primarily by below-average rainfall during 2000 (a dry year) and above-average rainfall during 2005 (a wet year).

Scientific Investigations Report↗
USGS2020

Water withdrawals, uses, and trends in Florida, 2015

In 2015, the total amount of water withdrawn in Florida was estimated to be 15,319 million gallons per day (Mgal/d). Saline water accounted for 9,598 Mgal/d (63 percent) and freshwater accounted for 5,721 Mgal/d (37 percent) of the total. Groundwater accounted for 3,604 Mgal/d (63 percent) of freshwater withdrawals and surface water accounted for the remaining 2,117 Mgal/d (37 percent). Surface-water sources accounted for 9,401 Mgal/d (98 percent) of the saline-water withdrawals, and groundwater sources accounted for the remaining 198 Mgal/d (2 percent). The majority of groundwater withdrawals (almost 62 percent) in 2015 were from the Floridan aquifer system, which is used throughout most of the State while the majority of fresh surface-water withdrawals (52 percent) occurred in the Southern Florida Subregion, a hydrologic unit that includes Lake Okeechobee and canals in the Everglades Agricultural Area. Groundwater provided drinking water (public supplied and self-supplied) for 18.324 million people (92 percent of Florida’s population), and fresh surface water provided drinking water for 1.491 million people (8 percent). Overall, public supply accounted for 39 percent of the total freshwater withdrawals (ground and surface) and 53 percent of groundwater withdrawals, followed by agricultural self-supplied uses, which accounted for 37 percent of the total freshwater withdrawals and 28 percent of groundwater withdrawals. Other self-supplied groundwater withdrawals include commercial-industrial-mining self-supplied (8 percent), recreational-landscape irrigation and domestic self-supplied (5 percent each), and power generation (less than 1 percent). Agricultural self-supplied withdrawals accounted for 51 percent of fresh surface-water withdrawals, followed by power generation (19 percent), public supply (15 percent), recreational-landscape irrigation (10 percent), and commercial-industrial-mining self-supplied (5 percent). In 1975, agricultural water withdrawals accounted for 43 percent of the total freshwater withdrawals, followed by power generation (24 percent) and public supply (17 percent). By 2000, agricultural withdrawals increased to 48 percent of the total freshwater withdrawals, followed by public supply (30 percent). For 2015, agricultural self-supplied decreased to 37 percent of total freshwater withdrawals, and was surpassed by public supply at 39 percent. Over the 40-year period between 1975 and 2015, increases in freshwater withdrawals caused by large gains in population and the expansion of irrigated acreage were offset by decreases in water used for power generation and commercial-industrial-mining withdrawals. Since 2000, however, irrigated acreage has decreased statewide because of crop disease, storm damage, and urbanization. This decline, coupled with large gains in water conservation measures in the farming industry, has led to agricultural withdrawals in Florida being less than public-supply withdrawals for the first time since water-use data were first reported in 1965.

Florida↗
USGS2021

Estimates of public-supply, domestic, and irrigation water withdrawal, use, and trends in the Upper Rio Grande Basin, 1985 to 2015

The Rio Grande flows approximately 670 miles from its headwaters in the San Juan Mountains of south-central Colorado to Fort Quitman, Texas, draining the Upper Rio Grande Basin (URGB) study area of 32,000 square miles that includes parts of Colorado, New Mexico, and Texas. Parts of the basin extend into the United Mexican States (hereafter “Mexico”), where the Rio Grande forms the international boundary between Texas and the State of Chihuahua, Mexico. The URGB was chosen as a focus area study (FAS) for the U.S. Geological Survey (USGS) National Water Census (NWC) as part of the WaterSMART initiative. The objective of the USGS NWC under WaterSMART is to focus on the technical aspects of providing information and tools to stakeholders so that they can make informed decisions on water availability. This report contains water-use withdrawal estimates of groundwater and surface water for public-supply, self-supplied domestic, and irrigation water use for years 1985–2015 at 5-year intervals for the 22 drainage basins at the subbasin 8-digit hydrologic unit code (HUC-8) level. Data for additional categories of self-supplied industrial, mining, livestock, aquaculture, thermoelectric, and hydroelectric water use are provided in the accompanying data release to illustrate total withdrawals for the URGB. The additional category data are provided in this report only for the year 2015. Deliveries of water from public-supply systems to domestic users are included and are the only water-delivery data presented in this report. Consumptive use for irrigation is reported for all HUC-8 subbasins for 2015 and for select HUC-8s in the other years beginning in 1985 (the irrigation category includes irrigation for both crop and golf). Water transported outside of the URGB (interbasin transfers) is not included as part of the withdrawals and are not accounted for in any category of use within the URGB. Estimated total withdrawals for all the water-use categories (including hydroelectric) in 2015 as reported in the USGS compilations in the URGB were 3,152.10 million gallons per day (Mgal/d). Surface water was the dominant source of water used in the URGB, providing about 71 percent of total withdrawals. Nearly all withdrawals were from freshwater sources; there was a small amount of saline groundwater that was used for public supply and self-supplied industrial, which were all reported in Texas. The proportions of total 2015 withdrawals from States in the URGB are 46 percent each in Colorado and New Mexico and 8 percent in Texas. A comparison of 2015 water withdrawals for the URGB—for the categories of public supply, self-supplied domestic, self-supplied industrial, thermoelectric, irrigation, livestock, mining, aquaculture, and hydroelectric—showed that irrigation is the dominant water use, at 74 percent of total withdrawals. Other water-use categories in the URGB that use about 1 percent or greater of the total water use by volume are public supply (9 percent) and self-supplied domestic and aquaculture (each about 1 percent). This report focuses on the higher volume, consumptively used categories of public supply, self-supplied domestic, and irrigation. A discussion on basin population provides context for the categories of public-supply and self-supplied domestic water use. The population in the part of the basin in the United States grew from 1.36 to 2.26 million people between 1985 and 2015. With the city of Ciudad Juarez, Chihuahua, Mexico, included, the total population of the URGB grew from an estimated 2.01 to 3.66 million people between 1985 and 2015. The largest concentrations of population are in New Mexico, Texas, and Chihuahua, with 98 percent of the total number of people in the basin in 1985 and 99 percent of the total in 2015 residing in these states. Albuquerque, El Paso, and Ciudad Juarez are the largest cities in the basin. Total withdrawals for public supply in the URGB averaged 277 Mgal/d from 1985 to 2015. About 60 percent of the URGB total public-supply withdrawals occurred in New Mexico, which averaged 170 Mgal/d. Groundwater provided 92 and 70 percent of the total withdrawals for public supply in 1985 and 2015, respectively. Deliveries to domestic users from public suppliers are reported for all drainage basins and years, and account for part of the total public-supply withdrawals. In the URGB, domestic deliveries from public suppliers increased from 1985 to 1995; since 2005, domestic deliveries from public supply have declined. The total populations served by public suppliers in the URGB increased by 90 percent from 1985 to 2015. In the URGB, more people were served by public-supply systems than were self-supplied, and the percentage of people on public-supply systems ranged from 81 to 92 percent from 1985 to 2015. Total domestic withdrawals in the URGB (deliveries plus self-supply withdrawals) ranged from 177.49 to 234.83 Mgal/d and peaked in 2005. Domestic use decreased from 2005 to 2010 by 17 percent and remained less than 200 Mgal/d in 2015. The per-capita daily use for the entire URGB fluctuated between the reporting years, but overall, domestic per-capita use across the basin has declined 46 percent from 145 gallons per capita daily (gpcd) in 1985 to 79 gpcd in 2015. Total irrigation withdrawals in the URGB had a mean value of 2,767.66 Mgal/d from 1985 to 2015 and withdrawals peaked in 1995 at 3,416.84 Mgal/d. Over the 30-year period, irrigation source water in the URGB has ranged from 69 to 84 percent surface water, and the most surface water diverted in the basin for irrigation was in 1995. Groundwater withdrawals for irrigation have fluctuated but overall decreased by 13 percent between 2005 and 2015. Slightly more than one-half of total irrigation withdrawals within the URGB occurred in Colorado, with a mean of 57 percent from 1985 to 2015. From the peak of water withdrawals in 1995 to the conclusion of this study in 2015, total irrigation withdrawals across the study area decreased by 32 percent. The total number of irrigated lands in the URGB from 1985 to 2015 had a mean of about 800 thousand acres, and more irrigated lands were consistently located in the headwaters of the URGB in the San Luis Valley, Colorado than the remainder of the study basin. In the 30-year period, Colorado had a mean of 68 percent of total irrigated lands whereas irrigated acres in New Mexico had a mean of 26 percent and the remaining 7 percent were in Texas. Since 2000, the number of irrigated acres in the URGB has fluctuated, but overall has decreased by 12 percent. More land was irrigated with surface systems (surface irrigation includes flood, furrow, and gated pipe systems, hereafter collectively termed “surface”) in the URGB than with other irrigation system types. Across the 30-year period, from 62 to 88 percent of total irrigated lands had surface-system irrigation, and surface systems covered a mean of 69 percent of the URGB’s acres. Microirrigation systems, predominantly in New Mexico and Texas, compose 0.2 percent or less of the irrigated acres in the basin and were first reported in 1995. From 1985 to 2015, the surface systems decreased in the basin by about 38 percent, and the number of acres of sprinkler and microirrigation systems increased. Acres irrigated by sprinkler systems (predominately center pivot systems) have increased 179 percent from about 99 thousand acres in 1985 to 275 thousand acres in 2015. In this dataset, the number of sprinkler acres surpassed the number of surface irrigated acres in 2000. Within the San Luis Valley in Colorado, the acreage of surface irrigation has decreased, and sprinkler irrigation has increased over the 30-year period. In the New Mexico part of the URGB, surface irrigation is reported as the dominant system type, where irrigation by surface systems accounts for 97–98 percent of how water is provided to crops. As in New Mexico, crops in Texas are irrigated primarily by surface systems. The mean of the mean simulated actual evapotranspiration (ETa) for crops in 2015 across the basin was highest for durum wheat at an estimated 36.00 inches per year (in/yr), and lowest for vegetables at an estimated 19.48 in/yr. Alfalfa and irrigated grass pastures mean ETa had a mean of 31.4 and 27.58 in/yr, respectively, for the basin. Pecans and peppers, both signature crops in the Rio Grande Basin, each had a mean ETa of 30.67 and 30.38 in/yr of mean. In general, mean ETa values for crops were lower in the HUCs of the Colorado San Luis Valley (13010001, 13010002, 13010003 and 13010004) which are more northerly and at higher elevations. The mean ETa for crops increased in the HUCs that are more southerly and at lower elevations in the basin.

New Mexico↗
USGS2024

Streamflow, base flow, and precipitation trends and simulated effects of Rush Springs aquifer groundwater withdrawals on base flows upgradient from Fort Cobb Reservoir, western Oklahoma

To better understand the relation between groundwater use in the Rush Springs aquifer and inflows to the Fort Cobb Reservoir, the U.S. Geological Survey, in cooperation with the Bureau of Reclamation, used a previously published numerical groundwater-flow model and historical streamflow records to evaluate four scenarios to investigate how changing groundwater withdrawals could affect base flows in streams that flow into Fort Cobb Reservoir. These scenarios consisted of observing simulated base-flow response by (1) scaling the 20-year equal-proportionate-share groundwater-withdrawal rate by various percentages over a 50-year period; (2) scaling the historical groundwater-withdrawal rates by various percentages across the entire Rush Springs aquifer; (3) scaling the historical groundwater-withdrawal rates within various subareas (zones) of the Fort Cobb Reservoir surface watershed; and (4) simulating a base-flow-depletion scenario. Cobb, Lake, and Willow Creeks are the major streams upgradient from the Fort Cobb Reservoir (listed from highest to lowest mean annual base flow). The results of scenarios 1 and 2 indicated that Willow Creek is the most susceptible to drying, but Cobb Creek was the most likely to have reduced base flow. Scenarios 3 and 4 indicated that groundwater withdrawals affect Cobb Creek base flows over a broader watershed area compared to Lake and Willow Creeks. In scenario 4, Cobb Creek base-flow depletion was higher across a larger area than Lake Creek and Willow Creek. Groundwater withdrawals in the Cobb Creek watershed tended to affect total inflows into Fort Cobb Reservoir more than other areas in the extent of the Rush Springs aquifer.

Oklahoma↗
USGS2025

A trend analysis and model comparison of total phosphorus concentrations and loads in the Boise River near Parma, southwestern Idaho, water years 2003–21

Total phosphorus (TP) concentrations and loads in the Boise River near Parma, Idaho, were examined to identify changes by month over a 19-year period from water year 2003 through water year 2021 and to evaluate the performance of three common water-quality models. Mean annual TP concentrations and loads were estimated to have reduced by approximately 60 percent over the study period. Mean annual TP concentrations were reduced from 0.42 milligrams per liter in 2003 to 0.18 milligrams per liter in 2021. Mean annual TP loads were reduced from 816 kilograms per day in 2003 to 302 kilograms per day in 2021. Mean annual concentrations and loads reduced by approximately 3 percent per year with the largest changes occurring in the non-irrigation season of October through April. The TP load remained highest in May across the model period while peak concentration shifted from January to March. High-frequency TP data collected with an automated sampler every 49 hours enabled detailed model performance evaluation of the Load Estimator (LOADEST), Weighted Regressions on Time, Discharge, and Season (WRTDS), and WRTDS method with Kalman filtering (WRTDS_K) water-quality models generated with near-monthly data. All three models were generally able to reproduce the observed concentrations, with the largest errors occurring in the spring when observed concentrations were most variable. Annual TP loads varied by up to 27 percent, or approximately 128,000 kilograms, between the three models calibrated on monthly data. In this system with highly variable concentrations, we note that performance metrics for WRTDS_K based on monthly calibration data masked serious errors that were only revealed by comparing results against higher frequency (49-hour) autosampler data. This emphasizes the value of high frequency validation data to quantify uncertainty in water-quality models when applied to systems where concentrations change rapidly. Lastly, we identify that hydraulic routing may be a valuable addition to discharge, season, and time in water-quality modeling for systems with significant human intervention in natural hydro-biogeochemical processes.

Idaho↗
USGS2026

Streamflow, base-flow, and precipitation trends and simulated effects of groundwater withdrawals from the North Fork Red River aquifer on base flows upgradient from Lake Altus, western Oklahoma, 1980–2022

The U.S. Geological Survey, in cooperation with the Bureau of Reclamation, used five scenarios created from a previously published numerical groundwater-flow model (1980–2013) and historical streamflow records (1980–2022) to investigate the relation between groundwater withdrawals from the North Fork Red River aquifer and inflows to Lake Altus from the North Fork Red River in western Oklahoma. The five scenarios were (1) a scaled-equal-proportionate-share (EPS) groundwater-withdrawal scenario, (2) a study-area-scaled-reported groundwater-withdrawal scenario, (3) a zonal-scaled-reported groundwater-withdrawal scenario, (4) a historical drought-threshold scenario, and (5) a base-flow and evapotranspiration depletion scenario. For the scaled-EPS groundwater-withdrawal scenario, EPS groundwater withdrawals were often much higher than reported groundwater withdrawals and greatly decreased base flows for most scale factors. For the study-area-scaled-reported groundwater-withdrawal scenario, base flows were reduced more but by smaller percentages during wet periods than during dry periods when scaling simulated reported groundwater withdrawals. For the zonal-scaled-reported groundwater-withdrawal scenario, scaling simulated reported groundwater withdrawals within selected zones with more groundwater withdrawals did not always affect base flows more than scaling reported groundwater withdrawals within zones with less groundwater withdrawals. For the historical drought-threshold scenario, curtailing groundwater withdrawals at the drought thresholds increased annual base flows to Lake Altus by about 1,169 to 3,665 acre-feet. For the base-flow and evapotranspiration depletion scenario, the distance between a groundwater well and a stream was a major factor affecting base flow to the North Fork Red River when increasing groundwater withdrawals; however, spatially variable hydrologic properties and saturated-zone evapotranspiration could also affect the relation between base flows and groundwater withdrawals.

Oklahoma↗
USGS2000

Contaminant trends in sport fish from Lake Roosevelt and the upper Columbia River, Washington, 1994-1998

Fish from Lake Roosevelt were first reported to contain elevated concentrations of contaminants in the early 1980?s, with mercury, dioxins and furans, and polychlorinated biphenyls (PCBs) identified as being of most concern to human health. Over the following years there were a series of studies by United States and Canadian agencies addressing contaminants in fish from both a human and environmental perspective. In the early 1990?s, industrial discharges to the Columbia River above the international boundary decreased. The dominant changes in industrial practices included a reduction in slag and effluent discharges from a lead-zinc smelter, and a reduction in dioxins and furans due to processing changes at a Canadian pulp mill. It is believed that these two alterations in industrial practices may have greatly reduced the loading of selected contaminants to the Columbia River system. In response to these recent changes, the U.S. Geological Survey initiated this present study for the purpose of determining the present concentrations of mercury, dioxins and furans, and PCBs in fish, and, if possible, to determine if concentrations have changed since the 1994 studies. All contaminant analysis was done on fish fillets in order to address human health concerns. Our study concluded that the concentrations of contaminants in fish that were identified as a potential threat to human health have either not changed since the 1994 studies, or have decreased. PCBs, as determined by Aroclor 1254, do not appear to have changed between 1994 and 1998; sources of PCBs are presently unknown. In contrast, dioxins and furans, as indicated by 2,3,7,8-TCDF, did show a significant decrease in rainbow trout fillets from 1994 to 1998. However, there was no apparent change in the average 2,3,7,8-TCDF concentrations in mountain whitefish, with the reason uncertain at this time. Average concentrations of 2,3,7,8-TCDF were higher in mountain whitefish than in rainbow trout. Toxicity equivalence concentrations (TEC) are determined by summing the relative toxicity of individual congeners of dioxins, furans, and toxic ?dioxin-like? PCB congeners in individual fish. Rainbow trout from the upper reach have higher TECs than rainbow trout from the lower reach, with trout from the upper reach having a higher percentage of the toxicity from toxic ?dioxin-like? PCBs than dioxin and furan compounds. In relation to mercury, the concentrations of total mercury in walleye have significantly decreased by about 50 percent from 1994 to 1998.

Water-Resources Investigations Report↗
USGS2003

Historical ground-water-flow patterns and trends in iron concentrations in the Potomac-Raritan-Magothy aquifer system in parts of Philadelphia, Pennsylvania, and Camden and Gloucester Counties, New Jersey

The Potomac-Raritan-Magothy (PRM) aquifer system is an important sole-source ground-water supply in Camden and Gloucester Counties, N.J. Elevated iron concentrations are a persistent water-quality problem associated with ground water from the PRM. In Philadelphia, the PRM no longer is usable as a water supply because of highly elevated concentrations of iron (as high as 429 mg/L [milligrams per liter]), manganese (as high as 4 mg/L), and sulfate (as high as 1,720 mg/L). A strongly reducing environment in the PRM in south Philadelphia causes these constituents to be remobilized by reductive dissolution of the aquifer matrix. By the 1920s, ground-water pumping changed the natural ground-water-flow patterns, and ground water flowed toward pumping centers in Philadelphia. By 1940, recharge areas changed from the topographically high areas east of Trenton, N.J., to the outcrop area of the PRM in Philadelphia, and the Delaware River became a source of recharge instead of a point of ground-water discharge. By 1954, the cone of depression caused by pumping at the former Philadelphia Naval Ship Yard (PNSY) exceeded 50 feet below NGVD 29, and the direction of ground-water flow was from New Jersey toward Philadelphia. Because of highly elevated concentrations of iron and manganese, pumping at the former PNSY ceased in the mid-1960s. Beginning about 1951, increased ground-water withdrawals from the PRM in New Jersey reversed the hydraulic gradient so that ground-water flow was from Philadelphia toward New Jersey under the Delaware River, making Philadelphia a recharge area for the PRM aquifer system in parts of Camden and Gloucester Counties. By 1988, water levels in the lower aquifer of the PRM in New Jersey had declined to 103 feet below NAVD 88. In 1943, dissolved iron concentrations ranged from 0.07 to 0.6 mg/L at the former PNSY. By 1967 when the wells at the PNSY were abandoned, dissolved iron concentrations had reached 46 mg/L. Dissolved iron concentrations in water from industrial wells in Philadelphia increased from 0.17 mg/L in 1949 to 19 mg/L in 1979. The concentration of dissolved iron in water from wells screened in the lower aquifer in New Jersey also increased with time. By 1985, dissolved iron concentrations were as high as 16 mg/L for Eagle Point refinery wells.

New Jersey, Pennsylvania↗
USGS1983

Trends in polychlorinated biphenyl concentrations in Hudson River water five years after elimination of point sources

Industrial discharge of polychlorinated biphenyls (PCBs) to the Hudson River from 1950 to the mid-1970 's has resulted in serious degradation of the water. Contaminated river-bottom sediments continue to contribute PCBs to the river water. Concentrations in the sediment range from several hundred micrograms per gram near the outfall to less than 10 micrograms per gram in the lower estuary. PCBs are supplied by bottom sediments to the overlying water by two mechanisms--desorption and resuspension. Because desorption is a relatively constant process, concentrations of PCBs decrease as water discharge increases. At high flow, however, scouring by turbulence causes resuspension of PCB-laden sediment. Transport rates indicate that most PCBs enter the water from the most contaminated sediments, which are within 20 kilometers of the outfall. Mean daily transport from the upper river (except during high discharges) has decreased from 10 kilograms in 1976 to 5 kilograms in the late 1970 's and to 1 kilogram in 1981. This decrease probably results from the burial of highly contaminated sediments by cleaner sediments originating upstream. (USGS)

Water-Resources Investigations Report↗