Skip Links

USGS - science for a changing world

Scientific Investigations Report 2009–5240

In cooperation with the Kentucky Energy and Environment Cabinet–Kentucky Division of Water

Concentrations, and Estimated Loads and Yields of Total Nitrogen and Total Phosphorus at Selected Stations in Kentucky, 1979–2004

By Angela S. Crain and Gary R. Martin

Scientific Investigations Report 2009-5240 and link to report PDF (3.29 MB)

Abstract

To evaluate the State’s water quality, the Kentucky Division of Water collects data from a statewide network of primary ambient stream water-quality monitoring stations and flexible, rotating watershed-monitoring stations. This ambient stream water-quality monitoring network program is directed to assess the conditions of surface waters throughout Kentucky. Water samples were collected monthly for the majority of the stations from 1979 to 1998, which represented agricultural, undeveloped (mainly forested), and areas of mixed land use/land cover. In 1998, the number of water samples collected was reduced to a collection frequency of six times per year (every 2 months) every 4 of 5 years, because a new monitoring network was implemented involving a 5-year rotating Basin Management Unit scheme of monitoring. This report presents the results of a study conducted by the U.S. Geological Survey, in cooperation with the Kentucky Energy and Environment Cabinet–Kentucky Division of Water, to summarize concentrations of total nitrogen and total phosphorus and provide estimates of total nitrogen and total phosphorus loads and yields in 55 selected streams in Kentucky’s ambient stream water-quality monitoring network, which was operated from 1979 through 2004.

Streams in predominately agricultural basins had higher concentrations of total nitrogen (TN) and concentrations of total phosphorus (TP) than streams in predominately undeveloped (forested) basins. Streams in basins in intensely developed karst areas characterized by caves, springs, sinkholes, and sinking streams had a higher median concentration of TN (1.5 milligrams per liter [mg/L]) than streams in basins with limited or no karst areas (0.63 mg/L). As with TN, median concentrations of TP also were higher in areas of intense karst (0.05 mg/L) than in areas with limited or no karst (0.02 mg/L).

The U.S. Environmental Protection Agency (USEPA) has recommended ecoregional nutrient water-quality criteria as a starting point for States to establish more precise numeric water-quality criteria for nutrients to protect aquatic life and recreational and other uses of rivers and streams. On the basis of the 25th percentile of concentration data from reference stations aggregated by ecoregion, the USEPA established recommended water-quality criteria for TN and TP in the two Aggregated Ecoregions (IX and XI) in Kentucky waters. The 25th percentile median values for TN and TP from this study exceeded the USEPA’s recommendations in both aggregated ecoregions in the agricultural and mixed land-use/land-cover basins, and for TN in the undeveloped land-use/land-cover basins in Aggregated Ecoregion XI. However, the 25th percentile median values for TN (Aggregated Ecoregion IX) and TP in both aggregated ecoregions did not exceed the USEPA’s recommendations in the undeveloped land-use/land-cover basins.

Estimated loads and yields of TN and TP varied substantially among the individual stations. Estimated mean annual yields of TN ranged from 0.10 [tons per year per square mile (ton/yr)/mi2] to 7.2 (ton/yr)/mi2, and estimated mean annual yields of TP ranged from 0.02 (ton/yr)/mi2 to 1.4 (ton/yr)/mi2. Estimated mean annual yields of TN and TP were generally highest at stations in predominately agricultural basins, and lowest at stations in undeveloped land-use/land-cover basins.

First posted December 2009

For additional information contact:
Director, Kentucky Water Science Center
9818 Bluegrass Parkway
Louisville KY 40299
Phone: (502) 493-1900
Fax: (502) 493-1909 http://ky.water.usgs.gov/

Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Acrobat® Reader, free of charge.


Suggested citation:
Crain, Angela S., and Martin, G.R., 2009, Concentrations, and estimated loads and yields of total nitrogen and total phosphorus at selected stations in Kentucky, 1979–2004: U.S. Geological Survey Scientific Investigations Report 2009–5240, 48 p.


Contents

Abstract

Introduction

Data Collection

Concentrations, and Estimated Loads and Yields of Nutrients

Summary and Conclusions

References Cited

Appendix 1. Percent land use/land cover of watersheds represented by selected Kentucky Energy and Environment Cabinet–Kentucky Division
    of Water ambient water-quality network stations, 2001

Appendix 2. Regression equations and coefficients of determination (R2) for load models used to estimate loads of total nitrogen for selected
   ambient water-quality monitoring stations in Kentucky, 1979–2004

Appendix 3. Regression equations and coefficients of determination (R2) for load models used to estimate loads of total phosphorus for selected
   ambient water-quality monitoring stations in Kentucky, 1979–2004


Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: http://pubs.usgs.gov/sir/2009/5240/
Page Contact Information: Contact USGS
Page Last Modified: Thursday, January 10 2013, 07:42:16 PM