For the Yaquina Estuary, median values of TSS were similar within Zones between wet and dry 
seasons, but Zone 1 median values were approximately half that of Zone 2 values (Table 9.2). This 
pattern is consistent with the presence of a turbidity maximum at 14 km up the estuary, within Zone 2. 
There was a significant difference in median TSS between the Yaquina (dry season), Classification 
Study, and NCA datasets for both Zones 1 and 2 (Kruskal-Wallis one way ANOVA on ranks, p<0.001; 
Table 9.2). Comparison of the Yaquina Estuary data to that from both the Classification and NCA data 
sets showed some differences in zonal patterns. In Zone 1, there was not a significant difference 
between median TSS levels between the Classification and Yaquina data sets, but the Zone 2 median 
value in the Classification data set was significantly lower (66%) than the value for the Yaquina 
(Dunn’s method for pairwise comparison, p<0.05). NCA data for TSS showed still a different pattern 
across the region, where the median value was significantly higher (23%) than for the Yaquina in Zone 
1, while the median value was significantly lower (50%) than that for the Yaquina in Zone 2 (Table 
9.2; Dunn’s method for pairwise comparison, p<0.05). This pattern from the NCA data was present 
regardless of whether samples from the Columbia River Estuary were included. 
The NCA study used a probability based sampling within the dry season that was generally 
random with respect to tidal stage. Much of the sampling from the Yaquina Estuary for TSS was from 
cruises during flooding tides. It is not clear whether the zonal pattern differences observed were the 
result of methodology differences or that the Yaquina Estuary is somehow different in its spatial 
pattern for TSS. 
63 
< f 
