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2003 PRW E. coli Bacteria Data (in colonies per 100 mL of sample)

Columns are sample dates, rows are sample sites:

	17-May-03	31-May-03	14-Jun-03	28-Jun-03	12-Jul-03	26-Jul-03	9-Aug-03	23-Aug-03
P200	3	19	231	18	11	7	4	24
P170	0	5	40	nd	6	nd	18	5
P160	3	11	12	nd	10	nd	22	5
P150	7	9	40	nd	11	nd	7	11
P110	nd	64	83	57	17	nd	20	21
P089	9	102	770	326	86	nd	162	83
P080	11	105	579	101	102	nd	145	80
P065	7	41	83	21	20	nd	nd	16
P060	11	41	135	35	58	nd	nd	15
P030	33	99	517	76	68	nd	99	56
P020	70	130	365	81	142	nd	115	70
P010	15	165	649	38	201	1203	387	50
OB010	20	45	1203	363	365	nd	1553	579
BB010	5	76	>2419	291	105	162	133	707
DB010	6	38	1414	57	56	nd	44	43
PL040	51	74	>2419	722	1860	nd	727	951
PL030	23	66	>2419	326	166	64	186	145
PL020	37	62	1203	517	138	nd	138	nd
PL010	17	3	579	55	58	39	44	54
N010	nd	nd	nd	nd	nd	nd	nd	nd
BL010	6	25	>2419	102	161	nd	109	126
CW010	7	75	>2419	210	>2419	nd	291	43
CW020	16	83	>2419	866	687	nd	nd	172
DG010	9	54	1203	44	133	nd	190	39
L020	75	1203	1553	64	96	nd	150	50
L010	1	2	>2419	47	76	nd	308	114
IN010	16	125	2419	219	980	nd	186	11
M030	5	70	113	272	nd	11	22	31
M010	14	36	>2419	291	nd	nd	308	613
PI020	29	104	>2419	166	201	138	125	130
PI010	14	115	>2419	79	205	89	228	130
TA010	23	nd	>2419	54	88	51	210	84
TA020	nd	nd	411	nd	nd	nd	nd	nd
TA040	12	nd	>2419	76	50	55	91	nd

* Lack of data for 7/26/03 due to shortage of lab supplies (ran out of sample vessels).

WHAT DO THESE RESULTS MEAN?

The State Legislature has established statutes that classify Maine surface waters on the basis of water quality standards and intended uses. The Maine Department of Environmental Protection is charged with ensuring that these standards are met for all surface waters in the State. The classification scheme and standards for E. coli are as follows:

· Class A: suitable for drinking (after disinfection), swimming and fishing
· Class B: suitable for drinking (after treatment), swimming and fishing
· Class C: suitable for drinking (after treatment), swimming and fishing

The main stem of the Presumpscot River is Class A from the Eel Weir Dam to its confluence with the Pleasant River (just below sample site P150); Class B from the Pleasant River to the Saccarappa Dam (just below sample site P060); and Class C from the Saccarappa Dam to the estuary in Falmouth (just below the former site of the Smelt Hill Dam).

E. coli Standards
· Class A: as naturally occurs
· Class B: between May 15th and September 30th, E. coli may not exceed a seasonal geometric mean of 64 colony forming units (cfu's) per 100 mL or an instantaneous level of 427 cfu's per 100 mL
· Class C: between May 15th and September 30th, E. coli may not exceed a seasonal geometric mean of 142 cfu's per 100 mL or an instantaneous level of 949 cfu's per 100 mL

Class B sample sites are considered to be in violation of the State's water quality standards if the E. coli results are greater than 64 cfu's / 100 mL on any given sampling event or greater than 427 cfu's / 100 mL for the seasonal geometric mean. For Class C sample sites, E. coli cannot exceed 142 cfu's / 100 mL on an instantaneous basis or 949 cfu's / 100 mL for the seasonal geometric mean.

E. coli bacteria indicate the presence of fecal contamination that can originate from a variety of sources. These include point sources such as wastewater treatment plant discharges and combined sewer overflows; and nonpoint sources such as livestock waste from agricultural runoff, failing septic systems, pets and wildlife. E. coli by itself is generally not a threat to human health, but its presence is associated with disease-causing organisms that do pose potential health risks.

Despite the importance of measuring fecal concentrations in surface waters, it is virtually impossible to distinguish between the sources of fecal contamination with conventional test methods like the one used by PRW. However, routine monitoring can identify problem areas where the implementation of best management practices (BMPs) for nonpoint source pollution may help reduce fecal contamination. Such BMPs might include maintaining vegetated buffers along river or stream corridors; implementing erosion or sediment control measures for new construction; installing fencing for livestock; and establishing stormwater management practices to reduce urban and agricultural runoff.

Key to PRW Abbreviations: P = Main stem of Presumpscot River, BB = Baker Brook, BL = Black Brook, CW = Colley Wright Brook, DG = Douglas Brook, DB = Ditch Brook, IN = Inkhorn Brook, L = Little River, M = Mill Brook, N = Nason Brook, OB = Otter Brook, PI = Piscataqua River (not the same as one at ME-NH border), PL = Pleasant River, TA = Tannery Brook.

The "% complete" column indicates the number of samples actually collected compared to the number of samples intended for collection. PRW has 8 sampling events per season, so if only 4 samples were collected for the season the completion rate would be 50%.