17
National Nonpoint Source Monitoring Program November 2011
Richards, R.P. and D.B. Baker. 1993. Trends in nutrient and suspended sediment
concentrations in Lake Erie tributaries, 1975-1990. J. Great Lakes Res. 19(2):200-211.
Thas O., L. Van Vooren, and J.P. Ottoy. 1998. Nonparametric test performance for trends
in water quality with sampling design applications. J. American Water Resour. Assoc.
34(2):347-357.
US EPA. 1997a. Linear regression for nonpoint source pollution analysis. EPA-
841-B-97-007. Office of Water, Washington, DC.
US EPA. 1997b. Monitoring guidance for determining the effectiveness of nonpoint
source control projects. EPA 841-B-96-004. Office of Water, Washington, DC.
Walker, J.F. 1994. Statistical techniques for assessing water quality effects of BMPs. J. Irr.
Drainage Eng. ASCE. 120(2):334-347.
Ye, Y-S and S. Zou. 1993. Relating trends of principal components to trends of water-
quality constituents. Water Resour. Bull. 29(5):797-806.
Further Reading and Resources
There is far more to trend analysis than is covered in this technical note. For more
details on the techniques and calculations discussed, examples, and information on other
approaches, consult these additional sources:
Berryman, D., B. Bobee, D. Cluis, and J. Haemmerli. 1988. Nonparametric tests for trend
detection in water quality time series. Water Resour. Bull. 24(3):545-556.
Gilbert, R.O. 1987. Statistical methods for environmental pollution monitoring. New York:
Van Nostrand Reinhold.
Grabow, G.L., L.A. Lombardo, D.E. Line, and J. Spooner. 1999. Detecting water quality
improvement as BMP effectiveness changes over time: use of SAS for trend analysis.
NWQEP Notes No. 95. NCSU Water Quality Group, NC State University, Raleigh, NC.
Hirsch, R.M, J.R. Slack, and R.A. Smith. 1982. Techniques of trend analysis for monthly
water quality data. Water Resour. Res. 18:107-121.
Practical Stats, offering statistical training for environmental sciences and natural resources,
with emphasis on applied environmental statistics, nondetects data analysis, and
multivariate analysis. http://www.practicalstats.com/index.html [Accessed 9-15-2011].
Rheem, S. and G.I. Holtzman. 1990. A SAS program for seasonal Kendall trend analysis
of monthly water quality data. Proceedings, Sixteenth Annual SAS Users Group
International (SUGI) Conference, February 17-20, 1991, New Orleans.
Richards, R.P. and D.B. Baker. 2002. Trends in water quality in LEASEQ rivers and
streams (northwestern Ohio), 1975-1995. J. Environ. Qual. 31(1): 90 - 96.
Taylor, C.H. and J. C. Loftis. 1989. Testing for trend in lake and ground water time
series. Water Resour. Bull. 25(4):715-726.