Trends for High Concern Marine Beaches Analysis of High Concern beaches from 2000 to 2015 suggested that higher mean beach closure events corresponded with higher total precipitation through 2009 (Figure 3). Beach closures spiked in wet seasons (2003, 2006, 2009). After 2009, this trend of a high number of beach closures corresponding to wet years was not apparent. Figure 3. High Concern beaches: Mean and range of beach closure events in Narragansett Bay from 2000 to 2015. Shown with total seasonal precipitation (inches) from Memorial Day to Labor Day. Wet and dry seasons are indicated. Note: Before 2002, fewer beaches were monitored. Regional analysis of mean closure events indicated that High Concern beaches in all regions of the Bay followed the pattern described above (Figure 4). Mean closure events in 2009 were among the highest in all regions, ranging between 4.4 and 5.5. In contrast, mean closure events for High Concern marine beaches in each estuary region during the wettest season on record (2013) were less than half, compared to 2009, with a range between 0.5 and 2.4. Across estuary regions, High Concern marine beaches in the Upper Estuary exhibited the highest annual mean closure events in the majority of years on record (including highest mean in 2015), and this pattern does not appear to be triggered only by rainfall. Figure 4. High Concern beaches: Mean closure events between 2000 to 2015 in Narragansett Bay for each estuary region shown with total seasonal precipitation (inches). Note: Before 2002, fewer beaches were monitored. Trends for Low Concern Marine Beaches Among Low Concern beaches, precipitation and mean closure events appeared to be linked in most years on record (Figure 5). The magnitude of mean closure events was much lower compared to High Concern beaches, and the maximum Low Concern mean closure events observed in this record never exceeded 1 closure event per beach per year. It should be noted that mean closure events were calculated using a demonimator of 27 Low Concern beaches classified using 2015 Tier assignments (and separated by estuary region when applicable). While the denominator in this analysis was constant, in reality, it is possible that this total changed from one year to the next if beaches were tiers. Nevertheless, the determinants of frequency of monitoring per year are largely qualitative, and so the number of beaches sampled each year can be assumed to be constant (1) and the patterns observed are thus within reason.
Trends for High Concern Marine Beaches Analysis of High Concern beaches from 2000 to 2015 suggested that higher mean beach closure events corresponded with higher total precipitation through 2009 (Figure 3). Beach closures spiked in wet seasons (2003, 2006, 2009). After 2009, this trend of a high number of beach closures corresponding to wet years was not apparent. Figure 3. High Concern beaches: Mean and range of beach closure events in Narragansett Bay from 2000 to 2015. Shown with total seasonal precipitation (inches) from Memorial Day to Labor Day. Wet and dry seasons are indicated. Note: Before 2002, fewer beaches were monitored. Regional analysis of mean closure events indicated that High Concern beaches in all regions of the Bay followed the pattern described above (Figure 4). Mean closure events in 2009 were among the highest in all regions, ranging between 4.4 and 5.5. In contrast, mean closure events for High Concern marine beaches in each estuary region during the wettest season on record (2013) were less than half, compared to 2009, with a range between 0.5 and 2.4. Across estuary regions, High Concern marine beaches in the Upper Estuary exhibited the highest annual mean closure events in the majority of years on record (including highest mean in 2015), and this pattern does not appear to be triggered only by rainfall. Figure 4. High Concern beaches: Mean closure events between 2000 to 2015 in Narragansett Bay for each estuary region shown with total seasonal precipitation (inches). Note: Before 2002, fewer beaches were monitored. Trends for Low Concern Marine Beaches Among Low Concern beaches, precipitation and mean closure events appeared to be linked in most years on record (Figure 5). The magnitude of mean closure events was much lower compared to High Concern beaches, and the maximum Low Concern mean closure events observed in this record never exceeded 1 closure event per beach per year. It should be noted that mean closure events were calculated using a demonimator of 27 Low Concern beaches classified using 2015 Tier assignments (and separated by estuary region when applicable). While the denominator in this analysis was constant, in reality, it is possible that this total changed from one year to the next if beaches were tiers. Nevertheless, the determinants of frequency of monitoring per year are largely qualitative, and so the number of beaches sampled each year can be assumed to be constant (1) and the patterns observed are thus within reason.