This Atlas portrays the 'trophic status' of Lake Erie, mostly for the early years of monthly monitoring from 1966 to 1986 by ships and staff of Canada's Environment and Fisheries Departments from their Burlington laboratory called the Canada Centre for Inland Waters. The structure or distribution of water temperature is thoroughly displayed, because of its importance in relation to water quality and especially the water-masses of well-mixed character. Secchi transparency was quite variable and had a broad minimum, that is, maximum turbidity, in the 1970's decade. Data for chlorophyll a in the Central Basin during July and August indicated declining valued to 1986, the last year considered. That trend is probably a response to reduced external loading of phosphorus from urban and agricultural areas, which was the goal of the 1972 Great Lakes Water Quality Agreement between the United States and Canada. The author's diagrams of distributions of dissolved oxygen show trends in the vulnerable Central and Eastern hypolimnions. A recovery of dissolved oxygen by 1984 is not revealed. Particulate organic carbon, particulate nitrogen, and particulate phosphorus all declined (up to 1984), confirming the observed changes in the chlorophyll a data. The measurements of 'total phosphorus' in the water samples showed no change in the mid-summer values up to 1984. The early work by Dr. Julian Williams of the National Water Research Institute, on apatite and related minerals in Lake Erie sediments, could perhaps be extended to the water column. Mineral equilibria could be stabilizing the phosphorus concentrations in some fractions.

Agricultural Issues: The Nebraska Perspective (p. 269) Hydropolitical Solutions to Complex Nonpoint Salinity Pollution Problems in the Colorado River Basin (p. 273) Accumulation of Sediment, Nutrients, and Cesium-137 in Prairie Potholes in Cultivated and Noncultivated Watersheds (p. 274) Irrigated Agriculture and Nonpoint Source Pollution in the San Joaquin Valley of California (p. 276)

National Perspective on Environmental Constraints to Hydroelectric Development (p.301) Perspectives on Septic Tanks as Nonpoint Source Pollution (p. 304) Hydrologic Modification: Compounding the Impact of Nonpoint Source Pollution (p. 306)

Identifying Critical NPS Contributing Watershed Areas (p. 247) Gross Erosion Rates, Sediment Yields, and Nutrient Yields for Lake Erie Tributaries: Implications for Targeting (p. 251) Watershed Water Quality Programs: Lessons Learned in Illinois (p. 256) Prairie Rose Lake Rural Clean Water Program Project (p. 259) Agricultural Sources of Nitrate Contamination in a Shallow Sand and Gravel Aquifer in Eastern South Dakota (p. 264)

Nonpoint Source Control Programs (p. 221) The Status of Silvicultural Nonpoint Source Programs (p. 223) The Association of State and Interstate Water Pollution Control Administrators (p. 227)

What Do You Do with a Regulation? (p. 209) A National Perspective for Livestock Waste Management (p. 211) Ecopsychorrhea (p. 213) Controlling Water Pollution from Nonpoint Source Livestock Operations (p.215) Application of New Technologies to Livestock Waste Management (p. 218)

Ground Water Contamination by Aldicarb Pesticide in Eastern Suffolk County, Long Island (p. 101) Nonpoint Source Contamination of Ground Water in Karst-Carbonate Aquifers in Iowa (p. 109) An Interdisciplinary Approach to Shallow Ground Water Contamination in North-Central Montana (p. 115) Nonpoint Source Impacts on Ground Water Quality in Major Land Resource Areas of the Southwest (p. 121) Monitoring the Effects to the Ground Water System Attributable to Agricultural Practices (p. 125)

Forty-five observation wells and test holes were installed at two chemical waste disposal sites in Oswego County, New York, to evaluate the hydrogeologic conditions and the rate and direction of leachate migration. At the site near Oswego groundwater moves northward at an average velocity of 0.4 ft/day through unconsolidated glacial deposits and discharges into White Creek and Wine Creek, which border the site and discharge to Lake Ontario. Leaking barrels by chemical wastes have contaminated the groundwater within the site, as evidenced by detection of 10 ' priority pollutant ' organic compounds, and elevated values of specific conductance, chloride, arsenic, lead, and mercury. At the site near Fulton, where 8,000 barrels of chemical wastes are buried, groundwater in the sandy surficial aquifer bordering the landfill on the south and east moves southward and eastward at an average velocity of 2.8 ft/day and discharges to Bell Creek, which discharges to the Oswego River, or moves beneath the landfill. Leachate is migrating eastward, southeastward, and southwestward, as evidenced by elevated values of specific conductance, temperature, and concentrations of several trace metals at wells east, southeast, and southwest of the site. (USGS)

An Overview of the National Nonpoint Source Policy (p. 47) Intergovernmental Coordination: Feast or Famine? (p. 51) The Basic Legal Issues (p. 55) Compelling On-The-Ground Implementation of Measures to Control Nonpoint Source Pollution (p. 60) Controlling Nonpoint Sources of Pollution - The Federal Legal Framework and the Alternative of Nonfederal Action (p. 63)