Nutrient inputs from an urbanized landscape may drive water quality degradation

Estuaries are increasingly affected by deteriorating water quality associated with a burgeoning human population. As such, there is a need to establish water quality baselines and elucidate whether shifts in water quality are attributed to anthropogenic activities or the dynamic nature of estuaries. Here we investigate an extensive water quality dataset collected from 2006 to 2015 within the Loxahatchee River, Florida watershed. Results indicate substantial spatial variation in water quality within the watershed, though most locations were in line with established state water quality standards. Chlorophyll a state nutrient criteria had the greatest number of exceedances over the period of record in brackish and marine river regions, while freshwater regions exhibited the most variable water quality conditions overall. Water quality appears to be largely influenced by suburban stormwater runoff, septic tank effluent, and relic row crop agricultural practices, though more work is required to identify point and non-point sources of nutrient loading. Most sites were phosphorus-limited, likely as an indirect result of anthropogenic activities, phosphorus adsorption to carbonate sediments, and freshwater phosphorus limitation. Systematic water quality monitoring efforts are critical to help resource managers improve the ecological integrity of estuaries.