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At least 289 records · Page 16Linked to original sources

USGS2000

Trends in surface-water quality during implementation of best-management practices in Mill Creek and Muddy Run Basins, Lancaster County, Pennsylvania

Analyses of water samples collected over a 5-year period (1993-98) in the Mill Creek and Muddy Run Basins during implementation of agricultural best-management practices (BMP’s) indicate statistically significant trends in the concentrations of several nutrient species and in nonfilterable residue (suspended solids). The strongest trends identified were those indicated by a more than 50- percent decrease in the flow-adjusted concentrations of total and dissolved phosphorus and total residue in base flow in the two streams. Analyses of stormflow samples showed a 31-percent decrease in the flow-adjusted concentration of total phosphorus in Mill Creek and a 54-percent decrease in total nonfilterable residue in Muddy Run. A 58-percent increase in the flow-adjusted concentration of total ammonia nitrogen in stormflow was found at Muddy Run. Although the effects of a specific BMP on the indicated trends is uncertain, results of statistical trend tests of the data suggest that stream fencing, possibly in concert with other practices, such as stream crossings for livestock, barnyard runoff control, manure-storage facilities, and rotational grazing, was effective in improving water quality during base flow and probably low to moderate stormflow conditions. Additional improvements in water quality in the Mill Creek and Muddy Run Basins seems likely as the implementation of BMP’s is expected to continue. Thus, the full effect of BMP implementation in the two basins may not be observed for some time.

Fact Sheet↗

USGS2014

Late Holocene vegetation, climate, and land-use impacts on carbon dynamics in the Florida Everglades

Tropical and subtropical peatlands are considered a significant carbon sink. The Florida Everglades includes 6000-km 2 of peat-accumulating wetland; however, detailed carbon dynamics from different environments within the Everglades have not been extensively studied or compared. Here we present carbon accumulation rates from 13 cores and 4 different environments, including sawgrass ridges and sloughs, tree islands, and marl prairies, whose hydroperiods and vegetation communities differ. We find that the lowest rates of C accumulation occur in sloughs in the southern Everglades. The highest rates are found where hydroperiods are generally shorter, including near-tails of tree islands and drier ridges. Long-term average rates of 100 to >200 g C m −2 yr −1 are as high, and in some cases, higher than rates recorded from the tropics and 10–20 times higher than boreal averages. C accumulation rates were impacted by both the Medieval Climate Anomaly and the Little Ice Age, but the largest impacts to C accumulation rates over the Holocene record have been the anthropogenic changes associated with expansion of agriculture and construction of canals and levees to control movement of surface water. Water management practices in the 20th century have altered the natural hydroperiods and fire regimes of the Everglades. The Florida Everglades as a whole has acted as a significant carbon sink over the mid- to late-Holocene, but reduction of the spatial extent of the original wetland area, as well as the alteration of natural hydrology in the late 19th and 20th centuries, have significantly reduced the carbon sink capacity of this subtropical wetland.

Florida↗

USGS2013

The 3D Elevation Program: summary for Wisconsin

Wisconsin↗

USGS2013

The 3D Elevation Program: summary for Minnesota

Minnesota↗

USGS2014

The 3D Elevation Program: summary for Ohio

Elevation data are essential to a broad range of applications, including forest resources management, wildlife and habitat management, national security, recreation, and many others. For the State of Ohio, elevation data are critical for agriculture and precision farming, natural resources conservation, flood risk management, infrastructure and construction management, water supply and quality, and other business uses. Today, high-density light detection and ranging (lidar) data are the primary sources for deriving elevation models and other datasets. Federal, State, Tribal, and local agencies work in partnership to (1) replace data that are older and of lower quality and (2) provide coverage where publicly accessible data do not exist. A joint goal of State and Federal partners is to acquire consistent, statewide coverage to support existing and emerging applications enabled by lidar data. The National Enhanced Elevation Assessment evaluated multiple elevation data acquisition options to determine the optimal data quality and data replacement cycle relative to cost to meet the identified requirements of the user community. The evaluation demonstrated that lidar acquisition at quality level 2 for the conterminous United States and quality level 5 interferometric synthetic aperture radar (ifsar) data for Alaska with a 6- to 10-year acquisition cycle provided the highest benefit/cost ratios. The 3D Elevation Program (3DEP) initiative selected an 8-year acquisition cycle for the respective quality levels. 3DEP, managed by the U.S. Geological Survey, the Office of Management and Budget Circular A–16 lead agency for terrestrial elevation data, responds to the growing need for high-quality topographic data and a wide range of other 3D representations of the Nation's natural and constructed features.

Ohio↗

USGS2015

The 3D Elevation Program: summary for Iowa

Elevation data are essential to a broad range of applications, including forest resources management, wildlife and habitat management, national security, recreation, and many others. For the State of Iowa, elevation data are critical for agriculture and precision farming, infrastructure and construction management, natural resources conservation, flood risk management, water supply and quality, and other business uses. Today, high-density light detection and ranging (lidar) data are the primary sources for deriving elevation models and other datasets. Federal, State, Tribal, and local agencies work in partnership to (1) replace data that are older and of lower quality and (2) provide coverage where publicly accessible data do not exist. A joint goal of State and Federal partners is to acquire consistent, statewide coverage to support existing and emerging applications enabled by lidar data. The National Enhanced Elevation Assessment evaluated multiple elevation data acquisition options to determine the optimal data quality and data replacement cycle relative to cost to meet the identified requirements of the user community. The evaluation demonstrated that lidar acquisition at quality level 2 for the conterminous United States and quality level 5 interferometric synthetic aperture radar (ifsar) data for Alaska with a 6- to 10-year acquisition cycle provided the highest benefit/cost ratios. The 3D Elevation Program (3DEP) initiative selected an 8-year acquisition cycle for the respective quality levels. 3DEP, managed by the U.S. Geological Survey, the Office of Management and Budget Circular A–16 lead agency for terrestrial elevation data, responds to the growing need for high-quality topographic data and a wide range of other 3D representations of the Nation’s natural and constructed features.

Iowa↗

USGS2023

The 3D Elevation Program—Supporting Minnesota's economy

Introduction In Minnesota, high-quality elevation data are essential for agriculture and precision farming, natural resources conservation, flood risk management, infrastructure and construction management, water supply and quality, coastal zone management, and many other business uses. Critical applications that meet the State’s management needs depend on light detection and ranging (lidar) data that provide a highly detailed three-dimensional (3D) model of the Earth’s surface and aboveground features.

Minnesota↗

USGS1973

Map of land status in the Phoenix area, Arizona, 1973

No abstract available.

Arizona↗

USGS2002

Evaluation of artificial recharge in the Mojave River Ground-Water Basin, California

The Mojave River Basin relies almost entirely on ground water to meet the needs of its growing population and agriculture, which has resulted in overdraft conditions. Some of the ground-water management alternatives being proposed to mitigate the effects of overdraft include artificial recharge using water from the California State Water Project (SWP) and using SWP water in lieu of ground-water pumpage. A calibrated ground-water flow model was used to evaluate six proposed water-management alternatives using SWP water during a 20-year simulation period, 2000-2019, using constant rates from 1999 for recharge and pumpage (with the exception of recharge derived from Mojave River streamflows which were variable). The measured streamflow for the period of 1970-1989 was used to simulate the Mojave River streamflow. Water-management alternative 1 assumed that none of the Mojave Water Agency allocation of SWP water was available for mitigation measures and resulted in increases in hydraulic head in the floodplain aquifer in years of above-average streamflow (2008-2010, 2013) and decreases in years of below average streamflow. In general, simulated hydraulic heads in the regional aquifer declined with the exception of the El Mirage and Harper Lake areas. Also, average storage depletion for the entire ground-water basin over the 20-year simulation was 40,940 acre-feet per year. Water-management alternative 2 assumed that 30,000 acre-feet per year of SWP water was artificially recharged at Rock Springs Road Outlet (RSO). By 2019, the simulated hydraulic heads were as much as 75 feet higher in the Alto at the recharge site, 24 feet higher in the Transition zone, 15 feet higher in the Centro, and 17 feet higher in the Baja model subareas than the hydraulic heads resulting from water-management alternative 1. Water-management alternative 2 affected simulated hydraulic heads by as much as 5 feet in an area totalling 290 square miles; most of the change occurred in the Alto and Baja model subareas. Average storage depletion for water-management alternative 2 for the entire ground-water basin for the 20-year simulation period was 15,880 acre-feet per year, 25,060 acre-feet per year less than water-management alternative 1. Also, water-management alternative 2 indicated that the artificial recharge at RSO resulted in less simulated ground-water recharge from stream leakage in the Alto model subarea, which led to greater streamflow at the Lower Narrows, Barstow, and Afton Canyon streamflow gages. This increased streamflow resulted in an increase in simulated ground-water recharge from stream leakage, primarily in the Centro and Baja model subareas. Water-management alternative 3 assumed that 4,000 acre-feet per year of SWP water was artificially recharged at Manzanita and Oro Grande Washes (a total of 8,000 acre-feet per year) in the Alto model subarea. By 2019, the simulated hydraulic heads beneath the recharge sites were as much as 278 feet higher than heads resulting from water-management alternative 1. Changes in simulated hydraulic head greater than 5 feet covered almost 138 square miles in the Alto model subarea. Water-management alternative 3 had little effect on simulated hydraulic heads in the other model subareas. Model results indicated that the average storage depletion for the entire ground-water basin during the 20-year simulation was 32,940 acre-feet per year, about 8,000 acre-feet per year less than water-management alternative 1. Water-management alternative 3 had essentially no effect on simulated streamflows during the 20-year simulation period and, therefore, little effect on simulated net stream leakage. Water-management alternative 4 assumed 10,000 acre-feet per year of SWP water was artificially recharged near Newberry Springs in the Baja subarea. By 2019, the simulated hydraulic heads beneath the recharge site were as much as 193 ft higher in the Baja model subarea than the hydraulic heads resulting from water-management alternative 1. Increases in simulated hydraulic heads greater than 5 feet extended about 5 miles east of the Calico-Newberry Fault and affected about 71 square miles east of the Calico-Newberry Fault. Water-management alternative 4 had no effect on simulated hydraulic heads in the other model subareas. Model results indicated that the average storage depletion for the entire ground-water basin over the 20-year simulation period was 30,860 acre-feet per year, about 10,000 acre-feet per year less than water-management 1. Water-management alternative 4 had little effect on simulated streamflows during the 20-year simulation period and, therefore, essentially no effect on simulated net stream leakage. Water-management alternative 5 assumed 23,800 acre-feet per year of SWP water was delivered directly to municipal water districts in lieu of pumpage in the Alto model subarea. By 2019, the simulated hydraulic heads were as much as 98 feet higher in the Alto and 7 feet higher in the Centro and Baja model subareas than hydraulic heads resulting from water-management alternative 1. Changes in simulated hydraulic head were greater than 5 feet in an area of almost 245 square miles. Most of the change in simulated hydraulic heads occurred in the regional aquifer west of the Mojave River in the Alto model subarea. Average storage depletion for the entire ground-water basin over the 20-year simulation period was 19,170 acre-feet per year, 21,770 acre-feet per year less than water-management alternative 1. Results from water-management alternative 5 were similar to those of water-management alternative 2 in that they indicated that the in lieu replacement of ground water resulted in less simulated ground-water recharge from stream leakage in the Alto model subarea, and thereby streamflow at the Lower Narrows and Barstow gages. This increased streamflow resulted in an increase in simulated ground-water recharge from stream leakage primarily in the Baja model subarea. Water-management alternative 6 assumed 3,800 acre-feet per year of SWP water was delivered directly to municipal water districts in lieu of pumpage in the Transition zone model subarea. By 2019, the simulated hydraulic heads were as much as 30 feet higher in the Transition zone model subarea than the hydraulic heads resulting from water-management alternative 1. Changes in simulated hydraulic head were greater than 5 feet in an area of almost 16 square miles in the Transition zone model subarea. Water-management alternative 6 had little effect on simulated hydraulic heads in the other model subareas. Average storage depletion for the entire ground-water basin over the 20-year simulation period was 38,090 acre-feet per year, 2,850 acre-feet per year less than water-management alternative 1. Also, simulation of water-management alternative 6 indicated in-lieu replacement of ground water resulted in less ground-water recharge from stream leakage in the Alto, Transition zone, and Centro model subareas, and thereby greater streamflow at the Barstow gage. This increased streamflow resulted in an increase in simulated ground-water recharge from stream leakage, primarily in the Baja model subarea.

Open-File Report↗

USGS2012

Occurrence of anthropogenic organic compounds and nutrients in source and finished water in the Sioux Falls area, South Dakota, 2009-10

Anthropogenic organic compounds (AOCs) in drinking-water sources commonly are derived from municipal, agricultural, and industrial wastewater sources, and are a concern for water-supply managers. A cooperative study between the city of Sioux Falls, S. Dak., and the U.S. Geological Survey was initiated in 2009 to (1) characterize the occurrence of anthropogenic organic compounds in the source waters (groundwater and surface water) to water supplies in the Sioux Falls area, (2) determine if the compounds detected in the source waters also are present in the finished water, and (3) identify probable sources of nitrate in the Big Sioux River Basin and determine if sources change seasonally or under different hydrologic conditions. This report presents analytical results of water-quality samples collected from source waters and finished waters in the Sioux Falls area. The study approach included the collection of water samples from source and finished waters in the Sioux Falls area for the analyses of AOCs, nutrients, and nitrogen and oxygen isotopes in nitrate. Water-quality constituents monitored in this study were chosen to represent a variety of the contaminants known or suspected to occur within the Big Sioux River Basin, including pesticides, pharmaceuticals, sterols, household and industrial products, polycyclic aromatic hydrocarbons, antibiotics, and hormones. A total of 184 AOCs were monitored, of which 40 AOCs had relevant human-health benchmarks. During 11 sampling visits, 45 AOCs (24 percent) were detected in at least one sample of source or finished water, and 13 AOCs were detected in at least 20 percent of all samples. Concentrations of detected AOCs were all less than 1 microgram per liter, except for two AOCs in multiple samples from the Big Sioux River, and one AOC in finished-water samples. Concentrations of AOCs were less than 0.1 microgram per liter in more than 75 percent of the detections. Nutrient concentrations varied seasonally in source-water samples from surface water and groundwater. In the Big Sioux River, nitrite plus nitrate concentrations were typically less than 1 milligram per liter as nitrogen, and reached a maximum of 4.06 milligrams per liter as nitrogen following a June 2010 storm. Nitrite plus nitrate concentrations in groundwater ranged from less than 0.1 to 0.701 milligram per liter as nitrogen. Eight of the AOCs detected have a human-health benchmark that could be used to evaluate the concentrations in a human-health context. Four AOCs had maximum concentrations within an order of magnitude of the benchmark, indicating that additional monitoring of the compound may be warranted. Three herbicides (atrazine, metolachlor, and prometon) and one degradate (deethylatrazine) were detected in finished-water samples as frequently as in source-water samples. The concentrations of herbicides in source water varied by an order of magnitude from the period of peak use (early summer) to the winter months. Groundwater and finished-water concentrations of atrazine were similar for the six sampling dates when groundwater was the only source water used. Upstream wastewater discharges contributed a fairly small percentage of the flow to the Big Sioux River near Sioux Falls, but several AOCs associated with wastewater were frequently detected. The interpretation of all potential sources of nitrogen cannot be accomplished by use of nitrogen and oxygen isotopes in nitrate alone, but provides a qualitative indication that very little nitrate originates from excess fertilizer runoff, and most nitrate originates from municipal wastewater effluent, manure runoff (either from field application or feeding operations), or fertilizers mineralized by processes in the soil.

South Dakota↗

USGS2017

Agricultural irrigated land-use inventory for Polk County, Florida, 2016

An accurate inventory of irrigated crop acreage is not available at the level of resolution needed to better estimate agricultural water use or to project future water demands in many Florida counties. A detailed digital map and summary of irrigated acreage was developed for Polk County, Florida, during the 2016 growing season. This cooperative project between the U.S. Geological Survey and the Office of Agricultural Water Policy of the Florida Department of Agriculture and Consumer Services is part of an effort to improve estimates of water use and projections of future demands across all counties in the State. The irrigated areas were delineated by using land-use data provided by the Florida Department of Agriculture and Consumer Services, along with information obtained from the South and Southwest Florida Water Management Districts consumptive water-use permits. Delineations were field verified between April and December 2016. Attribute data such as crop type, primary water source, and type of irrigation system were assigned to the irrigated areas. The results of this inventory and field verification indicate that during the 2016 growing seasons (spring, summer, fall, and winter), an estimated 88,652 acres were irrigated within Polk County. Of the total field-verified crops, 83,995 acres were in citrus; 2,893 acres were in other non-citrus fruit crops (blueberries, grapes, peaches, and strawberries); 621 acres were in row crops (primarily beans and watermelons); 1,117 acres were in nursery (container and tree farms) and sod production; and 26 acres were in field crops including hay and pasture. Of the total inventoried irrigated acreage within Polk County, 98 percent (86,566 acres) was in the Southwest Florida Water Management District, and the remaining 2 percent (2,086 acres) was in the South Florida Water Management District. About 85,788 acres (96.8 percent of the acreage inventoried) were irrigated by a microirrigation system, including drip, bubblers, and spray emitters. The remaining 3.2 percent of the irrigated acreage was irrigated by a sprinkler system (2,360 acres) or subsurface flood systems (504 acres). Groundwater was the primary source of water used on irrigated acreage (88 percent, or 78,050 acres); the remaining 10,602 acres (12 percent) used groundwater combined with surface water as the irrigation source. The irrigated acreage estimated by the U.S. Geological Survey (USGS) for this 2016 inventory (88,652 acres) is about 11 percent higher than the 79,869 acres estimated by the U.S. Department of Agriculture (USDA) for 2012. Citrus and pasture in Polk County show the biggest difference in irrigated acreage between the USGS and USDA totals. Irrigated citrus acreage inventoried in 2016 by the USGS totaled 83,996 acres, whereas the USDA reported 78,305 acres of citrus in 2012. The USGS identified 6 acres of irrigated pasture and 20 acres of hay, whereas the USDA reported 6,631 acres of irrigated pasture and 1,349 acres of hay for 2012. In general, differences between the 2016 USGS field-verified acreage totals and acreage published by the USDA for 2012 could be due to (1) irrigated acreage for some specific crops increased or decreased substantially during the 4-year interval between 2012 and 2016 because of production or economic changes, (2) the assumption that if an irrigation system was present, it was used in 2016, when in fact some landowners may not have used their irrigation systems during this growing period even if they had a crop in the field, or (3) the amount of irrigated acreage published by the USDA for selected crops may be underestimated as a result of how information is obtained and formulated by the agency during census compilations.

Florida↗

USGS2025

Long-term trends of streamwater chemistry in an agricultural watershed: Effects of anthropogenic and climatic factors

The chemistry of headwater streams is a key indicator of the health of riparian zones and surrounding terrestrial ecosystems. This chemistry is shaped by biogeochemical processes, including chemical weathering, and anthropogenic activities that interact with one another and are sensitive to climate. Elucidating trends in streamwater chemistry and the drivers that underpin them is essential for informing land-management decisions and anticipating water-quality issues that may affect downstream waters. In this work, we investigated the effects of anthropogenic and climatic factors on long-term variations in the chemistry of a first-order stream draining an agricultural catchment nested within the Sleepers River Research Watershed in Vermont, USA. We observed statistically significant increases in alkalinity and the concentrations of calcium and magnesium over a 31-year period for which 17 years of measurements were available. Through the application of generalized linear models, we found that the upward trends in alkalinity and calcium were associated with rising air temperatures, while a response to historical acid deposition played a minor role. We hypothesize that increased production of biogenic carbon dioxide and organic acids in soil and groundwater may lead to increases in chemical weathering rates under warmer climate conditions. This study emphasizes the important role of rising temperatures in the long-term increase in streamwater alkaline solutes, potentially overshadowing other influences like acidification recovery and agricultural practices. It also highlights the importance of comprehensive, long-term research to understand climate impacts on chemical weathering and inland water chemistry, which is critical for managing water quality and understanding regional and global carbon cycles.

Vermont↗

USGS2013

Monitoring of green infrastructure at The Grove in Bloomington, Illinois

The City of Bloomington, Illinois, restored Kickapoo Creek to a more natural state by incorporating green infrastructure—specifically flood-plain reconnection, riparian wetlands, meanders, and rock riffles—at a 90-acre park within The Grove residential development. A team of State and Federal agencies and contractors are collecting data to monitor the effectiveness of this stream restoration in improving water quality and stream habitat. The U.S. Geological Survey (USGS) is collecting and analyzing water resources data; Illinois Department of Natural Resources (IDNR) is collecting fish population data; Illinois Environmental Protection Agency (IEPA) is collecting macroinvertebrates and riparian habitat data; and Prairie Engineers of Illinois, P.C., is collecting vegetation data. The data collection includes conditions upstream, within, and downstream of the development and restoration. The 480-acre development was designed by the Farnsworth Group to reduce peak stormwater flows by capturing runoff in the reconnected flood plains with shallow wetland basins. Also, an undersized park bridge was built at the downstream end of the park to pass the 20-percent annual exceedance probability flows (historically referred to as the 5-year flood), but detain larger floods. This design also helps limit sediment deposition from sediments transported in the drainage ditches in the upper 9,000 acres of agricultural row crops. Maintaining sediment-transport capacity minimizes sediment deposition in the restored stream segments, which reduces the loss of riparian and wetland-plant communities and instream habitat. Two additional goals of the restoration were to reduce nutrient loads and maintain water quality to support a diverse community of biotic species. Overall, 2 miles of previously managed agricultural-drainage ditches of Kickapoo Creek were restored, and the park landscape maximizes the enhancement of native riparian, wetland, and aquatic species for the park’s trail system. The purpose of this fact sheet is to give an overview and examples of the data being collected.

Illinois↗

USGS1999

Freshwater discharge to Florida Bay

The South Florida Ecosystem Program is a collaborative effort by Federal agencies, working with State and local agencies, to help resolve land-use demands and water-supply issues in south Florida. The role of the U.S. Geological Survey in the program is to provide scientific insight into south Florida's hydrology and geology, which are an integral part of the fragile ecosystems of the Everglades, Florida Bay, and the Florida Keys. Historical changes in water-management practices to accommodate a large and rapidly growing urban population along the Atlantic coast, as well as intensive agricultural activities, have resulted in a highly managed hydrologic system with canals, levees, and pumping stations. These structures have altered the hydrology of the Everglades ecosystem, including Florida Bay. Currently, there are plans to change the quantity of water delivered to Everglades National Park and Florida Bay to restore the natural flow of the system. Florida Bay, home to several endangered species, is a valuable breeding ground for marine life and an important recreational and sport fishing area. Florida Bay encompasses about 850 square miles in total area with an average depth of less than 3.5 feet. It is bordered by the mainland portion of Everglades National Park to the north, the Florida Keys to the east and south, and is open to the Gulf of Mexico to the west. During the last decade, Florida Bay has experienced algal blooms and seagrass die-offs which are signals of ecological deterioration that has been attributed to an increase in salinity and nutrient content of bay waters. Salinity and nutrient content are directly related to the amount and quality of freshwater that enters the bay and to flow patterns within the bay. Restoration of the Florida Bay ecosystem requires a better understanding of the linkage between the amount of water and nutrients flowing into the bay and the salinity and quality of the bay environment.

Florida↗

USGS2026

Natomas basin giant gartersnake annual monitoring report 2024

The giant gartersnake ( Thamnophis gigas ) is a semi aquatic snake endemic to the Central Valley of California. After losing 95 percent of its historic wetland habitat (Frayer and others, 1989), giant gartersnakes became state and federally listed as a threatened species (California Fish and Game Commission, 1971; U.S. Fish and Wildlife Service 1993, 1999). Continued monitoring of current populations and implementation of suggested management actions is necessary to recover the species. The Natomas basin in Sacramento, California, supports a population of giant gartersnakes persisting in restored marshes and rice agriculture. This annual report summarizes the giant gartersnake monitoring project for 2024, focusing on the apparent survival, abundance, density, and distribution of the giant gartersnakes and the connectivity of habitat throughout the Natomas basin. In 2024, 131 giant gartersnakes were captured 216 times at 44 sites by hand or trap. The catch-per-unit effort decreased from 2023 to 2024 but was similar to other years of the study. Estimates of occupancy increased between 2023 and 2024, although the trend of occupancy from 2011 through 2024 is still decreasing overall at a mean annual rate of 3 percent per year. Apparent survival was much higher at Betts-Kismat-Silva from 2018 to 2019 and from 2021 to 2022 than in other years, but this may be partly attributed to different sampling efforts over the years. Trapping effort was more consistent in the Sills tract, and apparent survival was slightly higher in later years (2022–23 and 2023–24). Giant gartersnake populations appeared to remain stable in 2024, but abundance, density, survival, and distribution is highly variable across different sites and years of the study. Continued monitoring of the populations would allow for better trend estimates over time and assessment of the effects of management activities. Giant gartersnake populations throughout the basin and on reserve lands would likely benefit from the following: (1) creating more managed marsh; (2) increasing the amount of emergent tule vegetation in existing marshes (for example, Cummings, Natomas Farms, and Lucich South); (3) continuing to flood existing marshes in early spring; (4) maintaining rice agriculture; and (5) continuing research into conservation actions that target the giant gartersnake, such as habitat and water management and translocation.

California↗

USGS2019

Assessment of site-specific agricultural Best Management Practices in the Upper East River watershed, Wisconsin, using a field-scale SWAT model

The Great Lakes “Priority Watershed” effort targeted the Upper East River watershed, a 116.5 km2 tributary watershed to Green Bay in Wisconsin, to reduce sediment and nutrients entering Green Bay. A Soil and Water Assessment Tool (SWAT) model was created to determine the effectiveness of Best Management Practices (BMPs) derived from the U.S. Department of Agriculture-Natural Resources Conservation Service National Conservation Planning (NCP) Database. The model was calibrated at the monthly timestep for flow, sediment, dissolved reactive phosphorus (DRP), total phosphorus (TP), and total nitrogen (TN). Field- and watershed-scale sediment and nutrient reductions were calculated due to the implementation of 74 BMP combinations on dairy and cash grain rotations. Modeling results indicated that when multiple BMPs are placed on a field, especially those that included filter strips and grassed waterways, generally reduced sediment and nutrient loads more than a single BMP implementation. The most effective in-field practice at reducing DRP and TP on dairy fields was a combination of 5 different BMPs: cover crops, crop rotation, nutrient management plan, reduced tillage, and a filter strip. Conservation cover was the most effective practice at reducing sediment and nutrient yields. Sediment and nutrient loads decreased at the watershed scale as the quantity and coverage of BMPs increased. When all contracted NCP BMPs were simulated at the watershed scale, sediment loads were reduced 2%, while TP, DRP, TN and nitrate loads were reduced 20%, 9%, 24%, and 17%, respectively. Modeling scenarios indicated that as the number and area of BMPs were increased, sediment and nutrient load reductions were also increased.

Wisconsin↗

USGS1998

Probability of detecting atrazine/desethyl-atrazine and elevated concentrations of nitrate (NO2+NO3-N) in ground water in the Idaho part of the upper Snake River basin

Draft Federal regulations may require that each State develop a State Pesticide Management Plan for the herbicides atrazine, alachlor, cyanazine, metolachlor, and simazine. This study developed maps that the Idaho State Department of Agriculture might use to predict the probability of detecting atrazine and desethyl-atrazine (a breakdown product of atrazine) in ground water in the Idaho part of the upper Snake River Basin. These maps can be incorporated in the State Pesticide Management Plan and help provide a sound hydrogeologic basis for atrazine management in the study area. Maps showing the probability of detecting atrazine/desethyl-atrazine in ground water were developed as follows: (1) Ground-water monitoring data were overlaid with hydrogeologic and anthropogenic data using a geographic information system to produce a data set in which each well had corresponding data on atrazine use, depth to ground water, geology, land use, precipitation, soils, and well depth. These data then were downloaded to a statistical software package for analysis by logistic regression. (2) Individual (univariate) relations between atrazine/desethyl-atrazine in ground water and atrazine use, depth to ground water, geology, land use, precipitation, soils, and well depth data were evaluated to identify those independent variables significantly related to atrazine/ desethyl-atrazine detections. (3) Several preliminary multivariate models with various combinations of independent variables were constructed. (4) The multivariate models which best predicted the presence of atrazine/desethyl-atrazine in ground water were selected. (5) The multivariate models were entered into the geographic information system and the probability maps were constructed. Two models which best predicted the presence of atrazine/desethyl-atrazine in ground water were selected; one with and one without atrazine use. Correlations of the predicted probabilities of atrazine/desethyl-atrazine in ground water with the percent of actual detections were good; r-squared values were 0.91 and 0.96, respectively. Models were verified using a second set of groundwater quality data. Verification showed that wells with water containing atrazine/desethyl-atrazine had significantly higher probability ratings than wells with water containing no atrazine/desethylatrazine (p <0.002). Logistic regression also was used to develop a preliminary model to predict the probability of nitrite plus nitrate as nitrogen concentrations greater than background levels of 2 milligrams per liter. A direct comparison between the atrazine/ desethyl-atrazine and nitrite plus nitrate as nitrogen probability maps was possible because the same ground-water monitoring, hydrogeologic, and anthropogenic data were used to develop both maps. Land use, precipitation, soil hydrologic group, and well depth were significantly related with atrazine/desethyl-atrazine detections. Depth to water, land use, and soil drainage were signifi- cantly related with elevated nitrite plus nitrate as nitrogen concentrations. The differences between atrazine/desethyl-atrazine and nitrite plus nitrate as nitrogen relations were attributed to differences in chemical behavior of these compounds in the environment and possibly to differences in the extent of use and rates of their application.

Idaho↗

USGS2000

Design of a shallow ground-water network to monitor agricultural chemicals, Lake Wales Ridge, central Florida

Extensive agricultural land use and dynamic hydraulic connections between the land surface and ground-water resources render many of Florida's aquifers vulnerable to chemical contamination. In these areas, there is a need to monitor shallow ground water for agricultural chemicals to evaluate potential migration of the chemicals to the subsurface and to deeper aquifers, and to assess the effects of agricultural practices on ground-water quality. Historically, efforts to monitor water-table aquifers have been minimal compared with monitoring deeper aquifers used for municipal drinking-water supply. The Florida Department of Agriculture and Consumer Services has proposed the establishment of long-term, water-quality networks to monitor shallow ground water in agricultural areas of Florida. These networks will bridge the current information gap between local-scale short-duration field studies, which are required for pesticide licensing, and statewide monitoring of deeper ground-water resources. Laboratory (experimental) and short-term field evaluations of the transport of agricultural chemicals to the subsurface contain some degree of uncertainty due to widespread variations in environmental conditions. The proposed regional-scale shallow ground-water networks will serve as "early warning" networks to avoid contamination of ground-water resources. The objectives of these shallow ground-water networks are to provide information for early detection of pesticides and nitrate in the subsurface, and for evaluating temporal trends in concentrations in relation to changes in land use and agricultural practices. Information on trends is important to the U.S. Environmental Protection Agency, State agencies, and agricultural managers, and is an integral part of Florida's Pesticide Management Plan, which evaluates the effectiveness of implementing "best management practices" to minimize environmental impacts. Lake Wales Ridge in Polk and Highlands Counties has been identified by the Florida Department of Agriculture and Consumer Services as a pilot study area for implementing a regional shallow ground-water network. Information gained from designing the Lake Wales Ridge Network will be used to develop plans as similar networks are considered for other areas of Florida. Lake Wales Ridge is heavily utilized for citrus production, but the well-drained, clean sands underlying the region, coupled with a hydraulic connection with deeper karst formations, render the area extremely vulnerable to the transport and migration of agricultural chemicals within the subsurface. The network design for Lake Wales Ridge was developed on the basis of the objectives of monitoring, factors affecting aquifer vulnerability, probability (statistical) sampling theory, and specifications regarding well construction, sampling, and laboratory analysis. The network will provide estimates of regional pesticide and nitrate concentrations in targeted ground water, monitor for trends over time, and will provide baseline, regional-scale information. The areas targeted for sampling were citrus groves located on soils classified as vulnerable to leaching of agricultural chemicals, and ground water in close proximity to the water table. The duration of monitoring is planned to be long term. Chemicals targeted for monitoring include selected nutrients, trace elements, and pesticides used for citrus management. Standardization of field sampling and laboratory methods, and construction of a computerized data-base repository will be important for long-term utility of the data. The proposed network design consists of existing and newly drilled wells. Existing wells were evaluated as candidates for the network based on location and well-construction specifications for water-quality monitoring. Using probability selection techniques, new well locations were selected in areas that lacked adequate existing wells. Implementation of the network will occur in phases. Quarterly sampling of 13 Phase I wells commenced in April 1999. An additional 11 Phase II wells were added to the network in April 2000. Proposed locations have been identified for 8 Phase III wells. Future topics for study include a regional water-quality analysis, a network design evaluation, and consideration of local-scale studies needed to support regional monitoring efforts. An analysis of historical water-quality data for Lake Wales Ridge, including Phase I wells, is needed for the purpose of examining trends, providing a preliminary description of spatial and short-term variability in water quality, and evaluating the proposed network design for cost effectively meeting program objectives. Local-scale, process-oriented studies are needed to provide important information for evaluating regional water-quality data. Coordination between individuals conducting such local-scale studies and those interpreting regional sampling results will be considered as a component of the network design, and will require coordination between multiple agencies.

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