A quantitative measure of how well the model fit the observed data was obtained by calculating the root-mean-square error (RMSE) between the observed (OBSi) and predicted (PREDi) values averaged over the number of observations (n):

The RMSE was calculated from observed and simulated data for WY2003 for each canary node for both grids. The RMSE was evaluated using the geometric progression of e as “cut-off” values corresponding to EXCELLENT, GOOD, FAIR, POOR, and VERY POOR . The score was based on the average error (RMSEavg) for each canary node with four or more observations. The geometric progression of e simply provides a convenient cut-off to score the magnitude of the error and provide a relative score for how well the model performed.

The cut-off values used to score the RMSE between observed and predicted data

Value	RSME	Rating
e	RSME < 2.72	EXCELLENT
e²	2.72 < RSME < 7.39	GOOD
e³	7.39 < RSME < 20.09	FAIR
e⁴	20.09 < RSME < 54.60	POOR
e⁴	RSME >54.60	VERY POOR

In addition to the RMSE, the evaluation also considered whether the overall observed geometric mean was the same, underpredicted, or overpredicted by the geometric mean of the simulation. The means were considered the same if the predicted geomean was within 2.72 cfu/100 ml (e) of the observed mean. It underpredicted or overpredicted if the predicted mean was greater than or less than 2.72 cfu/100 ml (e) the observed geomean.

Comparison between the rating scores obtained using the average RMSE calculated from the 91 x 96 and 94 x 105 grids

	Predicted: 91x96			Predicted: 94x105			Comparison of Grids
Canary Node	Average		Geomean	Average		Geomean
Group Name	RMSE	Rating	Predicts	RMSE	Rating	Predicts
01-Dyes-Barker-Cr-	5.6	GOOD	SAME	5.59	GOOD	SAME	no change
02-Dyes-Chico-Cr--	16.9	FAIR	UNDER	26.89	POOR	UNDER	worsened
03-Dyes-Clear-Cr--	170.5	VERY POOR	UNDER	45.60	POOR	SAME	very improved
04-Dyes-DY24-Straw	41.1	POOR	UNDER	40.62	POOR	SAME	improved slightly
05-Dyes-DY28-ClamI	2.5	EXCELLENT	SAME	2.38	EXCELLENT	SAME	no change
07-Dyes-ErlandsPt-	6.7	GOOD	SAME	6.67	GOOD	SAME	no change
08-Dyes-M5-RockyPt	3.8	GOOD	UNDER	3.72	GOOD	UNDER	no change
09-Dyes-M7-MidWind	2.8	GOOD	SAME	2.93	GOOD	SAME	no change
10-Dyes-Windy-Pt--	7.0	GOOD	SAME	6.98	GOOD	SAME	no change
11-Dyes-wShore----	3.3	GOOD	SAME	3.17	GOOD	SAME	improved slightly
12-Ostrich-Bay-M6-	2.5	EXCELLENT	SAME	2.78	GOOD	SAME	worsened
13-Ostrich-eShore-	2.8	GOOD	SAME	2.82	GOOD	SAME	no change
14-Ostrich-JackPar	2.4	EXCELLENT	SAME	2.41	EXCELLENT	SAME	no change
15-Ostrich-OBCreek	6.4	GOOD	UNDER	6.53	GOOD	SAME	no change
16-OysterBay-all--	27.2	POOR	UNDER	13.29	FAIR	UNDER	improved
17-PhinnyBay-sEnd-	4.8	GOOD	UNDER	5.84	GOOD	UNDER	worsend slightly
18-POP-SN17-Waterm	6.3	GOOD	SAME	6.32	GOOD	SAME	no change
19-POP-Dee-Cr-----	40.6	POOR	UNDER	40.61	POOR	UNDER	no change
20-POP-IllaheeSPCr	1.9	EXCELLENT	SAME	1.86	EXCELLENT	SAME	no change
21-POP-M1-MidChann	4.4	GOOD	SAME	2.00	EXCELLENT	SAME	improved
22-POP-PO11-------	3.1	GOOD	SAME	3.06	GOOD	SAME	no change
23-POPASS-PO12----	2.1	EXCELLENT	SAME	2.05	EXCELLENT	SAME	no change
24-POP-SpringBroCr	5.0	GOOD	UNDER	5.00	GOOD	UNDER	no change
31-PWN-DY01-mouth-	2.9	GOOD	SAME	2.93	GOOD	SAME	no change
32-PWN-EvergrnPark	10.9	FAIR	UNDER	10.93	FAIR	UNDER	no change
33-PWN-AnCov-PineR	436.9	VERY POOR	UNDER	436.88	VERY POOR	UNDER	no change
34-RPass-ClamBay--	11.4	FAIR	UNDER	11.38	FAIR	UNDER	no change
35-RPass-FortWard-	374.9	VERY POOR	UNDER	374.92	VERY POOR	UNDER	no change
36-RPass-LynhwoodC	107.7	VERY POOR	UNDER	107.71	VERY POOR	UNDER	no change
37-RPass-M2-midChn	1.6	EXCELLENT	SAME	1.62	EXCELLENT	SAME	no change
38-RPas-SN18-Entra	4.1	GOOD	SAME	4.07	GOOD	SAME	no change
43-Sin-Gorst-Creek	7.7	FAIR	SAME	7.92	FAIR	OVER	no change
44-Sinclair-M3-mid	4.3	GOOD	SAME	4.33	GOOD	SAME	no change
45-Sinclair-M4-mid	9.3	FAIR	UNDER	9.80	FAIR	UNDER	worsened slightly
47-Sin-RossPt-SN08	5.7	GOOD	SAME	5.74	GOOD	SAME	no change
48-Sinclair-SaccoC	16.5	FAIR	SAME	16.48	FAIR	SAME	no change
49-Sin-SN03-PTOW--	5.9	GOOD	SAME	6.35	GOOD	SAME	no change
50-SinPO-BlackJ-Cr	42.2	POOR	UNDER	42.30	POOR	UNDER	no change
51-SinPO-KarcherCr	39.5	POOR	UNDER	39.61	POOR	UNDER	no change
52-SinPO-SN10-wfro	13.1	FAIR	UNDER	13.42	FAIR	UNDER	no change
53-Sin-SN11-12mari	20.4	POOR	UNDER	20.48	POOR	UNDER	no change

Summary of Verification Results