USGS Scientific Investigations Report 2013–5001  - Sources and Characteristics of Organic Matter in the Clackamas River, Oregon, Related to the Formation of Disinfection By-Products in Treated Drinking Water 

Table 11. Spearman rank correlations between carbon concentrations, optical properties, and disinfection by-product concentrations in finished water and DBP formation potentials for filtered and unfiltered samples from the Clackamas River basin, Oregon, 2010–11. 

[Spearman rank correlations (rho values), with P values indicated by asterisks: * (P<0.05); ** (P<0.01); ***(P<0.001). See table 6 for constituent abbreviations and units. Abbreviations: DOC, dissolved organic carbon; THM4, total trihalomethanes; HAA5, total haloacetic acids; DBP, disinfection by-product; STHMFP, carbon-specific total trihalomethane formation potential; SHAAFP, carbon-specific total haloacetic acid formation poential; F, filtered; U, unfiltered; –, not applicable or no data] 

Constituent	All sites	Finished water		All sites (basin-wide synoptic sampling events)
Constituent	DOC	THM4	HAA5	THMFP-F	THMFP-U	HAAFP-F	HAAFP-U	STHMFP-F	STHMFP-U	SHAAFP-F	SHAAFP-U
Quantitative constituents
Streamflow	–	**0.47	***0.64	–	–	–	–	–	–	–	–
pH	***-0.46	-0.33	**-0.50	**-0.41	**-0.40	***-0.50	***-0.51	0.27	*0.29	***-0.52	***-0.46
Turbidity	***0.72	**0.46	***0.55	***0.88	***0.93	***0.94	***0.95	*-0.29	-0.24	***0.71	***0.51
Chlorophyll-a	***0.53	-0.20	-0.16	***0.71	***0.71	***0.70	***0.72	*-0.29	*-0.31	***0.60	***0.47
Total organic carbon	***0.98	***0.63	***0.71	***0.95	***0.96	***0.98	***0.98	*-0.32	*-0.28	***0.75	***0.58
Dissolved organic carbon	–	***0.72	***0.83	***0.96	***0.95	***0.98	***0.97	*-0.34	*-0.28	***0.77	***0.62
Total particulate carbon	***0.87	0.32	***0.71	***0.87	***0.93	***0.93	***0.94	*-0.28	-0.26	***0.69	***0.49
UVA₂₅₄	***0.96	***0.67	***0.79	***0.94	***0.96	***0.98	***0.98	*-0.33	-0.27	***0.78	***0.60
Dissolved organic matter fluorescence	***0.98	***0.68	***0.81	***0.95	***0.93	***0.95	***0.94	*-0.34	*-0.28	***0.73	***0.58
PEAK A	***0.96	***0.65	***0.77	***0.93	***0.91	***0.92	***0.91	**-0.34	-0.28	***0.69	***0.53
PEAK C	***0.98	***0.67	***0.80	***0.94	***0.92	***0.94	***0.93	**-0.34	-0.28	***0.72	***0.56
PEAK M	***0.96	***0.64	***0.71	***0.93	***0.91	***0.92	***0.92	**-0.34	-0.28	***0.69	***0.53
PEAK D	***0.98	***0.68	***0.81	***0.96	***0.93	***0.95	***0.95	**-0.34	-0.28	***0.74	***0.59
PEAK B	***0.89	***0.60	***0.54	***0.85	***0.90	***0.93	***0.93	**-0.37	-0.30	***0.72	***0.51
PEAK T	***0.92	**0.46	**0.41	***0.88	***0.90	***0.92	***0.92	**-0.39	-0.32	***0.69	***0.51
PEAK N	***0.94	***0.53	***0.53	***0.91	***0.91	***0.92	***0.91	**-0.35	-0.29	***0.68	***0.51
C1 Loading	***0.91	***0.51	***0.54	***0.88	***0.87	***0.87	***0.87	*-0.33	-0.27	***0.63	***0.47
C2 Loading	***0.98	***0.67	***0.80	***0.96	***0.94	***0.96	***0.95	*-0.34	*-0.28	***0.74	***0.59
C3 Loading	***0.97	***0.68	***0.81	***0.95	***0.93	***0.94	***0.93	*-0.34	*-0.28	***0.72	***0.56
C4 Loading	***0.98	***0.68	***0.80	***0.95	***0.93	***0.95	***0.94	*-0.34	*-0.29	***0.73	***0.58
C5 Loading	***0.89	**0.50	**0.44	***0.85	***0.90	***0.92	***0.92	**-0.37	*-0.29	***0.69	***0.49
Qualitative constituents
SUVA	***0.49	**0.44	***0.59	***0.72	***0.67	***0.73	***0.73	**-0.39	**-0.37	***0.78	***0.70
Spectral slope (S_275–295)	***-0.46	**-0.40	-0.27	***-0.45	**-0.42	***-0.45	***-0.45	0.23	0.12	***-0.52	***-0.56
Spectral slope (S_290–350)	-0.18	-0.30	-0.19	-0.18	-0.23	-0.26	-0.26	-0.04	-0.10	-0.26	-0.28
Spectral slope (S_350–400)	0.24	0.05	0.23	0.26	0.23	0.19	0.18	-0.03	0.04	0.18	0.09
Spectral slope ratio	**-0.43	-0.30	**-0.37	**-0.44	-0.41	**-0.4	**-0.39	0.19	0.08	**-0.45	**-0.39
Fluorescence Index	0.18	-0.25	**-0.44	*0.28	0.23	0.17	0.17	-0.01	0.09	0.13	0.20
Humic Index	0.07	-0.12	-0.03	0.21	0.10	0.04	0.03	0.10	0.08	0.07	0.15
Percent component 1	***0.55	-0.04	-0.11	***0.57	***0.52	***0.48	***0.48	-0.23	-0.19	*0.29	*0.28
Percent component 2	-0.02	*0.37	***0.55	-0.03	-0.09	-0.08	-0.08	0.16	0.07	0.03	0.15
Percent component 3	-0.16	0.02	0.23	-0.14	-0.18	-0.24	-0.25	**0.38	*0.32	-0.18	-0.10
Percent component 4	-0.23	0.03	0.20	-0.16	-0.23	-0.24	-0.25	**0.36	0.26	-0.06	0.04
Percent component 5	-0.24	-0.21	**-0.45	**-0.41	*-0.30	-0.24	-0.23	-0.10	-0.06	-0.18	-0.27