Geology Reports⌕ Search

Geology topics

Evelyn H. Hopkins

Publications and source records attributed to Evelyn H. Hopkins.

6 recordsLinked to original sources
USGS2002

Water quality and aquatic communities of upland wetlands, Cumberland Island National Seashore, Georgia, April 1999 to July 2000

Cumberland Island is the southernmost and largest barrier island along the coast of Georgia. The island contains about 2,500 acres of freshwater wetlands that are located in a variety of physical settings, have a wide range of hydroperiods, and are influenced to varying degrees by surface and ground water, rainwater, and seawater. In 1999-2000, the U.S. Geological Survey, in cooperation with the National Park Service, conducted a water-quality study of Cumberland Island National Seashore to document and interpret the quality of a representative subset of surface- and ground-water resources for management of the seashore's natural resources. As part of this study, historical ground-water, surface-water, and ecological studies conducted on Cumberland Island also were summarized. Surface-water samples from six wetland areas located in the upland area of Cumberland Island were collected quarterly from April 1999 to March 2000 and analyzed for major ions, nutrients, trace elements, and field water-quality constituents including specific conductance, pH, temperature, dissolved oxygen, alkalinity, tannin and lignin, and turbidity. In addition, water temperature and specific conductance were recorded continuously from two wetland areas located near the mean high-tide mark on the Atlantic Ocean beaches from April 1999 to July 2000. Fish and invertebrate communities from six wetlands were sampled during April and December 1999. The microbial quality of the near-shore Atlantic Ocean was assessed in seawater samples collected for 5 consecutive days in April 1999 at five beaches near campgrounds where most recreational water contact occurs. Ground-water samples were collected from the Upper Floridan aquifer in April 1999 and from the surficial aquifer in April 2000 at 11 permanent wells and 4 temporary wells (drive points), and were analyzed for major ions, nutrients, trace elements, and field water-quality constituents (conductivity, pH, temperature, dissolved oxygen, and alkalinity). Fecal-coliform bacteria concentrations were measured, but not detected, in samples collected from two domestic water-supply wells. During the 12-month period from April 1999 to March 2000 when water-quality and aquatic-community samples were collected, rainfall was 12.93 inches below the 30-year average rainfall. Constituent concentrations were highly variable among the different wetlands during the study period. Rainfall and tidal surges associated with tropical storms and hurricanes substantially influenced water quantity and quality, particularly in wetland areas directly influenced by tidal surges. Although surface waters on Cumberland Island are not used as sources of drinking water, exceedances of U.S. Environmental Protection Agency primary and secondary standards for drinking water were noted for comparative purposes. A nitrate concentration of 12 milligrams per liter in one sample from Whitney outflow was the only exceedance of a maximum contaminant level. Secondary standards were exceeded in 26 surface-water samples for the following constituents: pH (10 exceedances), chloride (8), sulfate (5), total dissolved solids (4), iron (2), fluoride (1), and manganese (1). The total-dissolved-solids concentrations and the relative abundance of major ions in surface-water samples collected from wetlands on Cumberland Island provide some insight into potential sources of water and influences on water quality. Major-ion chemistries of water samples from Whitney Lake, Willow Pond, and South End Pond 3 were sodium-chloride dominated, indicating direct influence from rainwater, salt aerosol, or inundation of marine waters. The remaining wetlands sampled had low total-dissolved-solids concentrations and mixed major-ion chemistries--North Cut Pond 2A was magnesium-sodium-chloride-sulfate dominated and Lake Retta and the two beach outflows were sodium-calcium-bicarbonate-chloride dominated. The higher percent calcium and bicarbonate in some wetlands sugg

Georgia↗
USGS1996

Nutrient sources and analysis of nutrient water-quality data, Apalachicola-Chattahoochee-Flint River basin, Georgia, Alabama, and Florida, 1972-90

In 1991, the U.S. Geological Survey began full-scale implementation of the National Water-Quality Assessment (NAWQA) program. One of the initial tasks of the NAWQA program is to compile and evaluate existing data from individual study units. Available nutrient data from 1972 through 1990 water years were used to estimate nutrient sources to the Apalachicola–Chattahoochee–Flint (ACF) River basin and describe the presence, distribution, and transport of nutrients in surface and ground waters. In 1990, about 2,500 tons of nitrogen and 1,100 tons of phosphorus were discharged as point-source loads by 127 municipal wastewater-treatment facilities (WWTF). Nonpoint-source inputs, an unknown percentage of which entered the hydrologic system, included about 120,000 tons of nitrogen and 28,000 tons of phosphorus from animal manure; 82,000 tons of nitrogen and 20,000 tons of phosphorus applied as fertilizer; and 24,000 tons of nitrogen from atmospheric deposition. Estimates of nutrient input to the ACF River basin were not made for natural sources and for the following anthropogenic sources: industrial-wastewater effluent; storm drains; sanitary and combined sewer outflows; and runoff from agricultural, urban, and suburban areas. Nutrient outflow from the Apalachicola River into Apalachicola Bay, Fla., was about 13 percent of estimated nitrogen sources and about 3 percent of estimated total-phosphorus sources in the ACF River basin. For 1972–90, nutrient concentrations in surface water were high enough to warrant concerns about accelerated eutrophication based on total-phosphorus concentrations and to warrant concerns intermittently about toxicity to fish based on dissolved-ammonia concentrations downstream of wastewater-treatment outfalls from Metropolitan Atlanta and LaGrange, Ga. Many improvements to the water quality of the Chattahoochee and Flint Rivers in the 1980’s and early 1990’s can be directly attributed to improvements in WWTF, legislation directed at decreasing point-source loads of phosphorus, and changes in locations of wastewater-treatment outfalls. However, limited data indicate that nonpoint-source inputs increased upstream of Atlanta and in the Chipola River watershed. Significant increases in nutrient concentrations, loads, and yields occurred from upstream to downstream of the metropolitan areas of Atlanta, Ga.; Columbus, Ga., and Phenix City, Ala.; and Albany, Ga. The highest mean-annual yields estimated in the ACF River basin for total nitrogen (2.9 tons per square mile (tons/mi 2 )), total-inorganic nitrogen (2.0 tons/mi 2 ), dissolved ammonia (1.1 tons/mi 2 ), and total phosphorus (0.75 tons/mi 2 ) were downstream of Atlanta. Most significant trends in nutrient-concentration data from 1980–90 in the Chattahoochee River and the Middle and Lower Flint River basins were increasing, except dissolved ammonia which decreased at several sampling sites in reaches downstream of Atlanta, Columbus and Phenix City, and Albany. At sampling sites on the Chattahoochee and Flint Rivers downstream of Atlanta and Albany, decreasing trends in dissolved-ammonia concentration and increasing trends in dissolved-nitrate concentration were the result of improved wastewater treatment at WWTF. Dissolved-ammonia concentrations decreased and dissolved-nitrate concentrations increased along river reaches downstream of wastewater-treatment facility outfalls for Atlanta and Albany because of nitrification of ammonia to nitrate. Increasing trends in total-phosphorus concentrations are an accurate representation of data for the period 1980–90. However, legislated restrictions on the use of phosphate detergents and improvements to WWTF in the late 1980’s and early 1990’s, resulted in substantial reductions of phosphorus concentrations in wastewater effluent and in rivers at many locations in the 1990’s. Reservoirs affect nutrient transport because of uptake by phytoplankton and aquatic plants, denitrification,and accumulation of phosphorus associated with sediment in reservoirs. Yields of total-inorganic nitrogen, dissolved ammonia, dissolved nitrate, and total phosphorus decreased between sampling sites upstream and downstream of four reservoirs on the Chattahoochee River. The only exception was the yield of dissolved ammonia increased slightly from upstream to downstream of Lake Sidney Lanier. Much of the nutrient load in the Chattahoochee River downstream of Atlanta is utilized by algae or settles out primarily in West Point Lake, and to a lesser extent, in Lake Harding and Walter F. George Reservoir. In general, the Flint River arm of Lake Seminole had significantly higher concentrations of nutrients than the Chattahoochee River arm of Lake Seminole, which may be the result of the large percentage of the Middle and Lower Chattahoochee River in backwater from reservoirs, the absence of reservoirs on the Flint River downstream of Albany until Lake Seminole, and nonpoint-source inputs of nutrients from intensively farmed areas in the Lower Flint River basin. Decreases in dissolved-ammonia, dissolved-nitrate, and total-phosphorus concentrations in reservoirs and backwater along the Chattahoochee River from West Point Lake to Lake Seminole during summer months are related to the seasonality of phytoplankton production. The Chipola River had the highest yields of dissolved nitrate (1.2 tons/mi 2 ) estimated in the ACF River basin. Estimated loads of dissolved nitrate increased fairly steadily from 500 to 1,500 tons per year from 1972–90. These factors strongly suggest an agricultural nonpoint source of elevated dissolved-nitrate concentrations from increased irrigated agriculture and fertilizer applications in the Chipola River watershed. Analyses of nutrients in ground water within the ACF River basin for 1972–90 water years were restricted because of limited available data. The distribution of nitrate concentrations in the ACF River basin for 1972–90 water years included 10 percent of wells and 6 percent of springs with concentrations that probably have elevated nitrate concentrations (3.1 to 10 milligrams per liter (mg/L)), and 1 percent of wells with median nitrate concentrations exceeding the maximum contaminant level of 10 mg/L. Dissolved-nitrate concentrations were significantly lower in the Providence aquifer than in the Floridan aquifer system and the crystalline-rock aquifers. Dissolved-nitrate concentrations in wells used for public supply were significantly lower than in wells used for domestic use or unused wells.

Alabama, Florida, Georgia↗
USGS1995

Use and occurrence of pesticides in the Apalachicola-Chattahoochee-Flint River basin, Georgia, Alabama, and Florida, 1960-91

The Apalachicola-Chattahoochee-Flint (ACF) River basin was one of the first 20 study units selected in 1991 by the U.S. Geological Survey for its National Water-Quality Assessment (NAWQA) program. Because pesticide contamination of surface water and ground water is a concern nationwide, a major emphasis of the NAWQA program is to examine the occurrence and distribution of pesticides in the water resources of these study unit basins. An understanding of the types and distribution of land uses; pesticide properties, pest-control practices, and pesticide use; and an evaluation of the occurrence and distribution of pesticides in the water resources of the ACF are necessary to meet this objective of the NAWQA program. This report describes land use and pesticide use at a county level, and the occurrence and distribution of pesticides in the water resources of the ACF River basin on the basis of previously-collected data. About 33 percent of the ACF River basin is used for agriculture, 16 percent is used for silviculture, and about 5 percent of the basin is in urban and suburban settings; primarily the Columbus, Albany, and Atlanta Metropolitan areas. The remainder is in wetlands and non-silvicultural forest. A broad range of synthetic-organic herbicides, insecticides, and fungicides are applied to land in agricultural, silvicultural, urban, and suburban areas. The period of intensive pesticide applications extends from March to October. Pesticide data available for the period from 1971 through 1989 in the U.S. Geological Survey National Water Information System (NWIS) and for the period from 1960 through 1991 in the U.S. Environmental Protection Agency Storage and Retrieval System (STORET) were analyzed to describe the occurrence and distribution of pesticides in water resources of the ACF River basin. Collectively, the NWIS and STORET databases contain about 19,600 individual analyses for pesticide concentration in the ACF River basin. Pesticide concentrations were at or above a minimum reporting level in about five percent of all analyses. Most of the pesticide analyses and most of the analyses having concentrations above minimum reporting levels in these databases are for organochlorine insecticides in samples collected five or more years before this study. With few exceptions, most of organochlorine insecticides are now banned from use in the United States. Concentrations of currently (1991) used pesticides were at or above a minimum reporting level in about 0.3 percent of the analyses. The geographic patterns in the occurrence and distribution of pesticides in the ACF River basin (as defined by data collected during 1960-91) are, as expected, somewhat defined by land-use patterns. DDT (together with DDD and DDE) were detected in wide distribution in the sediments and aquatic biota of primarily mainstem and reservoir sites in the Chattahoochee, Flint, and Apalachicola drainages. DDT was used through 1973 as an insecticide on cotton, fruits, and vegetables; and for mosquito control, so its widespread occurrence in both urban and agricultural settings is consistent with its use. Chlordane, heptachlor, dieldrin, and related compounds were agriculturally used through 1974, but predominantly as termiticides through the late 1980’s. Compounds in these groups have been found in the sediments and aquatic biota of tributary streams draining the Atlanta Metropolitan area and of mainstem reaches and reservoirs of the Chattahoochee River downstream from the Atlanta and Columbus, Ga., Metropolitan areas. The phenoxy-acid herbicides are widely used in residential, commercial/industrial, agricultural, and silvicultural areas of the ACF River basin. Detectable concentrations of 2,4-D were found in most of the surface-waters sampled in the Atlanta Metropolitan area. It is unfortunate that only limited inference can be drawn on temporal patterns. Many of the Federal and State agency pesticide-monitoring programs have been targeted to known sources and areas of contamination, an approach consistent with regulatory requirements focused on human health; and either were synoptic in nature or were conducted during a limited period of time. Thus, the composite temporal picture represented by these sampling efforts is inherently patchy.

Alabama, Florida, Georgia↗
USGS1989

Effects of the 1986 drought on streamflow in Alabama, Georgia, North Carolina, South Carolina, Tennessee, and Virginia

A severe drought in the Southeastern United States during 1986 resulted in the lowest flows of record for many streams. Minimum flows in many streams occurred in mid-summer, several months earlier in the year than the minimums that occurred during notable regional droughts of 1954 and 1981. Streamflow data for 370 continuous-record gaging stations in Alabama, Georgia, North Carolina, South Carolina, eastern Tennessee, and southern Virginia were analyzed to determine the severity and areal extent of this drought. Minimum average streamflows for periods of 1, 7, 30, 60, and 90 consecutive days were evaluated to estimate the frequency of recurrence of the 1986 drought and generalized areas of similar recurrence intervals were delineated for the 7-day and 30-day minimum average flows. Flows in parts of Georgia, North Carolina, and Tennessee receded to rates estimated to occur on the average of once in 50 to 100 years. A much larger area that extended from central Alabama to central North Carolina experienced flows with estimated recurrence intervals of 20 to 50 years. In addition to the continuous-record station data, discharge measurements and observations of zero flow were made at 694 non-recording stream sites in Alabama, Georgia, South Carolina, and eastern Tennessee during the 1986 drought. These measurements were used in conjunction with the continuous-record station flow data to estimate minimum 1986 drought flows at the non-recording sites.

Alabama, Georgia, North Carolina, South Carolina, ↗