Water-Quality Assessment of Streams in Johnson County, Kansas

Mill Creek near Shawnee Mission Parkway.

Introduction

Johnson County, located in northeast Kansas, is the most populated county in the State according to the 2000 U.S. census, with more than 450,000 people. Urban, industrial, and agricultural land uses affect the water quality of streams and lakes in the county. Water-quality impairments have been identified by the Kansas Department of Health and Environment in several Johnson County streams including the Blue River and Indian, Mill, Cedar and Kill Creeks. Stream impairments are caused primarily by sediment, nutrients, and bacteria.

Purposes

The USGS, in cooperation with the Johnson County Stormwater Management Program, began a multi year study during the fall of 2002 to evaluate water quality in streams throughout the county.

Specifically, the purposes of the study are to:
   - describe water-quality conditions in streams throughout Johnson County, 
   - identify contaminant source areas, and 
   - estimate constituent concentrations, densities, and loads.

Approach

Water samples were collected from more than 40 stream locations during base-flow and stormflow conditions during 2002 through 2005. Base-flow is defined as the sustained low flow of a stream originating primarily from springs or ground-water recharge and from consistent point-source discharges such as wastewater-treatment facilities. In addition to analysis for sediment, nutrients, pesticides, and bacteria, samples were analyzed for compounds associated with wastewater such as caffeine, nicotine, hormones, antibiotics, and detergents. Sediment samples were collected from 15 sites and analyzed for the same compounds. Benthic macroinvertebrates also were collected at 15 sediment sites to assess cumulative water-quality effects on in-stream biota.

Also, continuous water-quality monitors were installed in Blue River, Cedar, Indian, Kill, and Mill Creeks are being used to provide round-the-clock information on the chemical and physical health of these water bodies. Regression models are being developed to provide continuous estimates of stream-water constituent concentrations or densities that are based on the relation between laboratory-analyzed samples and in-stream sensor measurements such as turbidity and specific conductance. Information from the continuous monitors is transmitted by satellite and available to the public in real time on the World Wide Web by selecting from the links provided below. 

The continuous data are used to: 
    - immediately recognize changes in water-quality conditions, 
    - provide continuous concentration, density, and load estimates for constituents of concern, and
    - evaluate long-term changes in total maximum daily loads (TMDLs) and resource management practices.

Benefits

This study will provide a comprehensive assessment of water-quality conditions in streams throughout Johnson County. Results will assist the county and its cities in identifying contaminant source areas and in developing and evaluating land-management plans that affect water quality.