The effects of precipitation, river discharge, land use and coastal circulation on water quality in coastal Maine

Abstract

Faecal pollution in stormwater, wastewater and direct run-off can carry zoonotic pathogens to streams, rivers and the ocean, reduce water quality, and affect both recreational and commercial fishing areas of the coastal ocean. Typically, the closure of beaches and commercial fishing areas is governed by the testing for the presence of faecal bacteria, which requires an 18–24 h period for sample incubation. As water quality can change during this testing period, the need for accurate and timely predictions of coastal water quality has become acute. In this study, we: (i) examine the relationship between water quality, precipitation and river discharge at several locations within the Gulf of Maine, and (ii) use multiple linear regression models based on readily obtainable hydrometeorological measurements to predict water quality events at five coastal locations. Analysis of a 12 year dataset revealed that high river discharge and/or precipitation events can lead to reduced water quality; however, the use of only these two parameters to predict water quality can result in a number of errors. Analysis of a higher frequency, 2 year study using multiple linear regression models revealed that precipitation, salinity, river discharge, winds, seasonality and coastal circulation correlate with variations in water quality. Although there has been extensive development of regression models for freshwater, this is one of the first attempts to create a mechanistic model to predict water quality in coastal marine waters. Model performance is similar to that of efforts in other regions, which have incorporated models into water resource managers' decisions, indicating that the use of a mechanistic model in coastal Maine is feasible.

Assessment of bacterial pathogens on edible macroalgae in coastal waters

“…Knowledge of the time required for water column bacteria to incorporate into the biofilm of macroalgae would have important implications in decisions based on when to harvest following anthropogenic or environmental events that may increase bacterial load (Lu et al 2008;Liu and Pang 2010). The winter-spring sampling season coincided with spring snowmelt and rain events that increased freshwater discharge from local rivers and terrestrial runoff and are often linked to increased fecal bacteria levels in coastal waters (Online Resource B; Prasad et al 2015;Tilburg et al 2015;Jokinen et al 2009).…”

“…Dominant pathways for human specific fecal contamination to coastal waters are often due to point source discharges of treated and untreated sewage, especially in the presence of combined wastewaterstormwater systems, while various nonpoint sources of general fecal contamination include terrestrial, agricultural, and stormwater runoff (Kay et al 2008;Wyer et al 2010). Increased watershed surface runoff and river discharges are linked to snowmelt and large precipitation events, leading to a seasonal effect of fecal pollution that can also be associated with increased coastal use in the summer months (Lipp et al 2001;Tilburg et al 2015). Additionally, fecal coliform abundance is correlated with increased human population, land development, and impervious coverage of a watershed (Mallin et al 2000;Shehane et al 2004).…”

Assessment of relationship between rainfall and Escherichia coli in clams (Chamelea gallina) using the Bayes Factor

“…Targeting these control measures requires a good understanding of environmental factors influencing the transport of faecal contaminants within the hydrological catchments, particularly from inputs from human sewage pollution to commercial sewage beds (Cheng et al , 2013 ; Ciccarelli et al , 2014 ). So far a number of studies have confirmed the link between precipitations and increased microbial pollution which can result in reduced water quality in coastal environments (Pommepuy et al , 2004 ; Strubbia et al , 2016 ; Tilburg et al , 2015 ).…”

“…Currently reductions in water quality after high precipitation events and the subsequent increases in river discharge lead local authorities to close shellfish harvesting areas after large events (Pommepuy et al , 2004 ). But the inability of local authorities to accurately predict these events or to immediately assess the water quality exacerbates the losses to fishing economies (Tilburg et al , 2015 ). So the need of accurate and timely predictions of water quality becomes acute.…”

Prediction of river temperature surges is dependent on precipitation method

“…Consequently, it may be difficult to infer links between precipitation and hydrological processes in urban catchments (Berne et al, 2004). This has implications for a multitude of water quality variables that are influenced by event rainfall (Sandoval, Torres, Duarte, & Velasco, 2014;Tilburg, Jordan, Carlson, Zeeman, & Yund, 2015).…”