Microbial Contamination of Drinking Water Supplied by Private Wells after Hurricane Harvey.

Hurricane Hurricane Harvey made landfall on the Texas Gulf Coast on August 25, 2017, as a Category 4 hurricane and caused widespread flooding. We explored spatial and temporal distributions of well testing and contamination rates; relationships between contamination and system characteristics and recovery behaviors; and efficacy of mitigation strategies. We estimated that over 500 000 well users (∼130 000 to 260 000 wells) may have been affected, but only around 15 000 well users (∼3800 to 7500 wells) had inundated systems based on inundation maps. Local health departments and our team sampled 8822 wells in 44 counties in the 10 months that followed. Total coliform occurrence was 1.5 times and Escherichia coli was 2.8 times higher after Hurricane Harvey compared to baseline levels. Microbial contamination was more likely (1.7-2.5 times higher) when wells were inundated and/or residents felt their water was unsafe. Although more wells in urban counties were affected, E. coli rates were higher in wells in rural counties. Disinfection did not always eliminate contamination, highlighting concerns about the implementation and efficacy of chlorination procedures. Despite this extensive well testing conducted after Hurricane Harvey, we estimate that only 4.1% of potentially affected wells were tested, underscoring the magnitude of recovery assistance needed to assist well users after flooding events.

Consumer water quality evaluation of private and public drinking water sources.

Private water wells have no requirements to be tested or monitored to ensure safe drinking water quality, and yet those receiving their primary drinking water from private supplies are more frequently confident that their tap drinking water is safe. Using data from surveys administered in 2008 and 2014, this study assesses public attitudes and perceptions regarding drinking water. This study examines the results of a random sample survey of Texans to evaluate citizen awareness and attitudes on water issues. Most respondents reported that they believe their drinking water is of high quality, with 81.4% responding that they believe their tap water is safe to drink. An even larger number, 92.1%, of those receiving their water from private sources believe their tap water is safe. Conversely, only 57.0% of respondents who consume bottled water as their primary source of drinking water believe their tap water is safe to drink. Additionally, more than 65% of Texans receiving their primary drinking water from private supplies (usually their private water well) have never had their water supply tested. A large majority (81.3%) of those primarily receiving their drinking water from private supplies believed groundwater in their area to be of good or excellent quality.

Impacts of Heronries on Water Quality as Evaluated through Escherichia coli and Fecal Sterol Analyses.

The authors used fecal sterol analysis to determine the potential contribution of E. coli from heronries to waterbodies in east-central Texas. They analyzed E. coli and fecal sterol concentrations in samples from four heronries during the breeding seasons in 2011-2013. The highest E. coli concentrations were in water samples from the two largest heronries established directly over water. The main sterols in fecal samples were cholesterol and stigmasterol, and in water, cholesterol, coprostanol, and cholestanol. Total sterols ranged 979 to 5838 ng/g dry weight in fecal samples, and 13 to 600 ng/L in water samples. There was a positive correlation between E. coli and the sum of bird sterols in water exposed directly to fecal deposition, but not in water surrounding the heronries. The authors found a strong association between E. coli and stigmasterol, suggesting that the presence of stigmasterol in water could be used for predicting E. coli sources from heronries nesting close to waterbodies.

Estimating the contribution of nitrogen and phosphorus to waterbodies by colonial nesting waterbirds.

Fecal deposition by colonial nesting waterbirds is a potential source of nutrient enrichment and pollution of nearby waterways. Excess concentrations of nitrogen (N) and phosphorus (P) can cause water quality concerns or impairment. We estimated concentrations of N and P deposited to waterbodies by birds nesting in four colonies in east-central Texas during 2011-2013, and developed an age-structured compartment model to estimate the amount of fecal N and P material deposited by birds during the entire breeding season. There was a seasonal variation in the accumulation of N and P in waterbodies where heronries were located with a significant increase from June to July at the peak of the breeding season. Also, there was a significant positive correlation in concentrations of N (P=0.023) in fecal material and water samples from one of the colonies (Murphy Park), suggesting a significant contribution of N from feces to water. Concentrations of N in water near the colonies were also significantly correlated (P=0.004, R2=0.22) with the average amount of precipitation recorded for each region. The simulation model results indicated that total N and P deposition increased proportionally with heronry size, and daily deposition rates varied due to the shifting daily activity budgets of the birds as the breeding season progressed. The total estimated loads from the model reached a maximum of 2170kg N and 240kg P for a given colony, with daily deposition estimated at 22.8kg N, and 2.5kg P. Based on the model, one bird can release about 1mg of N and 0.115mg of P on a daily basis to the soil substrate or directly over water. Results from this study could be useful to estimate the contribution of N and P from wildlife to waterbodies, and for watershed management plans.

An Evaluation of the Contribution of Macro- and Microelements from Colonial Nesting Waterbirds to Surface Water.

Macro- and microelements contained in the feces of cattle egrets () and other colonial birds in heronries can be sources of contamination of nearby waterways. Concentrations of the macroelements potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), sulfur (S) and the microelements zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), and boron (B) were measured in water and fecal samples collected from four locations containing heronries during the breeding seasons of 2011, 2012, and 2013. Nitrogen and phosphorus were measured but not reported in this study. Concentrations of K in feces ranged from 8.19 × 10 ± 4.38 × 10 to 4.88 × 10 ± 7.57 × 10 mg kg, and concentrations in water ranged from 3.92 ± 0.05 to 17.93 ± 0.37 mg L. Similarly, concentrations of Ca in feces ranged from 4.17 × 10 ± 1.84 × 10 to 1.16 × 10 ± 4.14 × 10 mg L, and concentrations in water ranged from 25.28 ± 0.89 to 67.88 ± 2.02 mg L. When birds nested directly over water, concentrations of K, Ca, and Mg in water were significantly higher ( < 0.05) than concentrations in water adjacent to birds nesting on islands. The results from this study show that macroelements from avian feces have the potential to enrich surface water and to negatively affect surface water quality. These results provide information regarding the contribution of nutrients from heronries (comprised primarily by cattle egrets) to watersheds.