Yields of selected constituents in base flow and stormflow in urban watersheds of Jefferson County, Kentucky, 1988-92

Abstract

In 1988, the U.S. Geological Survey began a cooperative program with the Louisville and Jefferson County Metropolitan Sewer District to assess the effects of urbanization on the water quality of streams in Jefferson County, Kentucky. This report presents mean annual base-flow and stormflow yields of selected water-quality constituents from watersheds of the county for 1988-92. These yields were estimated to help describe the proportions of constituent transport due to point and nonpoint sources. Dissolved-oxygen transport was related to the amount of nonurban land use in the watersheds. Chemical oxygen demand (COD) generally was greatest during stormflow and was related to the amount of industrial land use in each watershed. The highly industrialized Spring Ditch Watershed yielded nearly twice the COD-76.6 tons per square mile (ton/mi 2)-of any other sampled watershed in the county. Oxygen needed for biochemical oxidation of organic material in the water (BOD) was greatest in the Chenoweth Run Watershed (16.9 ton/mi 2). Dissolved-solids transport occurred primarily during stormflow except in the Fern Creek, Goose Creek, Little Goose Creek, Northern Ditch, and Spring Ditch Watersheds, an indication that these areas may be affected by pointsource discharges. Yields of dissolved solids in base flow ranged from less than 100 ton/mi 2 in the Mill Creek Watershed to greater than 300 ton/mi 2 in the Fern Creek, upper Goose Creek, and Northern Ditch Watersheds. Yields of dissolved solids in stormflow ranged from less than 100 ton/mi 2 in the lower Goose Creek and Mill Creek Watersheds to greater than 500 ton/mi 2 in the Chenoweth Run and lower South Fork Beargrass Creek Watersheds. Transport of volatile and nonvolatile suspended solids occurred primarily during stormflow. Nitrite and phosphorus transport was inversely proportional to the amount of nonurban and commercial land use in the watersheds. Nitrite transport occurred primarily during stormflow, except in the upper Goose Creek Watershed. Greater than 60 percent of the nitrate transport in the Goose Creek, Little Goose Creek, and Northern Ditch Watersheds occurred during base flow. Ammonia transport occurred primarily during stormflow except in the Little Goose Creek, Northern Ditch, and Spring Ditch Watersheds. Yields of total organic nitrogen in base flow were largest in the upper Goose Creek, Northern Ditch, Pennsylvania Run, and Spring Ditch Watersheds. Transport of metals from most of the watersheds occurred primarily during stormflow; however, yields of barium, copper, and iron in base flow exceeded yields in stormflow in the Goose Creek Watershed. Chromium and nickel yields were largest in the highly industrialized Spring Ditch Watershed. Yields of zinc in base flow and stormflow were related to the degree of urbanization in each watershed and were largest in the Muddy Fork Watershed. Purpose and Scope This report presents estimates of yields of selected water-quality constituents in base flow and stormflow in watersheds of Jefferson County, Ky. The yield of...