Lake Rotokakahi is a mesotrophic lake located within the Rotorua Lakes District, North Island, New Zealand. Under the legal guardianship of the Tuhourangi and Ngati Tumatawera tribes of Te Arawa it has remained closed to the public since 1948. Lake Rotokakahi was last monitored regularly in 1996 under the Environment Bay of Plenty (EBOP) water quality monitoring programme with only the lake outlet (Te Wairoa Stream) being monitored since that time. Water quality data collected up to 1996 suggests that there may be degradation of water quality in the lake, as indicated by declining levels of dissolved oxygen in the bottom waters. Lake Rotokakahi steeped in historical significance, as well as having major cultural and recreational values was well known for its abundant resources and as the name suggests, particularly for its massive supply of the freshwater mussel or kakahi (Hyridella menziesi). Freshwater mussel species worldwide are in decline however little is known on factors controlling kakahi abundance and distribution. The overarching objective of this thesis is update water quality data last monitored in Lake Rotokakahi in 1996 while also identifying key environmental variables thought to influence kakahi populations. This objective is underpinned by a number of aims that include: Establishment of a 12-13 month water quality programme within Lake Rotokakahi so that data is obtained for comparisons with previous water quality data (pre-1997) to allow assessment of whether there have been water quality changes in the lake. Conduct a population survey of the resident kakahi population examining possible environmental factors influencing their populations. Present an oral history of Lake Rotokakahi focusing on its historical significance, water quality, and collection of kairoto (food collected form lakes). from the 18 September 2006 to 14 September 2007 monthly water sampling was carried out at a mid lake station, the lake outflow and inflow for measures of nutrients, phytoplankton, zooplankton and chlorophyll a. Vertical profiles of temperature dissolved oxygen and chlorophyll fluorescence were also taken on various part of Lake Rotokakahi. A lengthened period of anoxia in the bottom waters during thermal stratification was recorded with increased levels of chlorophyll a in winter and reduced secchi disk depth indicating an increase in phytoplankton biomass. Nutrient concentrations remain moderate relative to historical data. On going water quality monitoring on Lake Rotokakahi is recommended to further evaluate the extent of which water quality change is occurring. This will provide a better understanding of how Lake Rotokakahi can be best managed to further preserve the lake. On 1 March and 20 April kakahi were sampled at five sites. Large kakahi densities were distributed predominantly in depths above the hypolimnion. Chlorophyll a fluorescence and dissolved oxygen were found to be the best correlates for kakahi density and biomass respectively. Low dissolved oxygen concentrations in the hypolimnion are thought to restrict kakahi distributions to above the thermocline in periods of hypolimnetic anoxia.

In this thesis, detection of active water-borne bacteria was achieved by combining flow cytometry with vital dyes that characterise the metabolic status of cells. Following optimisation, these techniques were applied to investigate the activity of bacteria exposed to disinfection, both in the laboratory and in real systems. Raw and potable waters from various locations around South Australia were then analysed to investigate relationships between numbers of active bacteria and those detected by traditional culture-based techniques. Flow cytometric cell sorting of active bacteria followed by 16S rRNA gene-directed PCR and denaturing gradient gel electrophoresis (DGGE) was then used to track the survival of bacteria through water treatment and into distribution. In doing so the identification of active bacteria not detected by culture was achieved. Finally, real-time PCR was optimised for detection of ammonia oxidising bacteria. This group of bacteria were responsible for loss of disinfection residual within a chloraminated distribution system. / thesis (PhD)--University of South Australia, 2005.

Graduation date: 1995

A model study has been conducted to understand the influence of hydrodynamic features, environmental conditions as well as bather shedding and animal fecal sources on the fate and transport of indicator microbe enterococci at a subtropical marine beach in South Florida. The model being used is based on an existing finite element hydrodynamic and transport model CAFE3D to which a first order microbe deactivation function due to solar radiation is added. The decay coefficient is assumed to be linearly proportional to the solar insolation value, while the constant coefficient linking the two is determined to be 0.368[m2/MJ] using local experimental data. This value corresponds to decay coefficients in the range of 0 to 1 hr-1 and is of similar magnitude to values found in the literature. The hydrodynamic model produces water current velocities, which are used in the transport model to simulate water enterococci concentration in space and time. Previous measurements have suggested that enterococci originate from the beach shoreline area. In this case the simulated velocity fields and Lagrangian particle trajectories indicate that the small velocity (generally less than 0.05m/s) and weak dilution at the water?s edge may cause enterococci accumulation and elevated concentration. Among human and animal sources, the impacts on maximum enterococci concentration in descending order is a dog fecal event, human bather shedding and seagull fecal events. A single dog fecal event at the middle part of the beach is found to cause enterococci far field concentrations to reach hundreds of CFU/100ml, which exceeds the EPA water quality standard (104 CFU/100ml). These high concentrations, however, only impact a small area. Concentration due to tens of bathers shedding enterococci during a course of 4 hours reaches 0.01 CFU/100ml, while the concentration due to thousands of bather shedding during a Memorial Day weekend reaches about 1 CFU/100ml. Concentration due to tens of seagull fecal events reaches only 0.0001 CFU/100ml. Thus, only the presence of dogs could explain the high enterococci observations infrequently found in monitoring data. The limited spatial extent compared to beach survey data of the enterococci plume from a dog fecal event suggests that other microbial sources are present, most likely microbes released from the beach sand.

Thesis (M.S.) -- University of Tennessee, Knoxville, 2006. / Title from title page screen (viewed on Feb. 7, 2007). Thesis advisor: Ernest Bazen. Vita. Includes bibliographical references.

Bacteria are the major cause of surface water contamination in the United States. US Environmental Protection Agency (USEPA) uses the Total Maximum Daily Load (TMDL) process to regulate the E. coli loads from fecal sources in a watershed. Different point and non-point sources can contribute to the fecal contamination of a waterbody including municipal and on-site wastewater treatment plants, livestock, birds, and wildlife. Unfortunately, wildlife sources in many rural watersheds are poorly characterized. E. coli is also known to persist in waterbodies when no known fecal sources are present. In this study, E. coli from wildlife fecal material was enumerated. It was found that E. coli concentrations varied with the season the fecal samples were collected. When studying the fate of E. coli under different environmental factors, no growth was observed in soil at 4% moisture content and in water at 10 degrees C. The highest E. coli growth was recorded in water at 30 degrees C. It can be seen from these results that there was variation in the fate of E. coli under different environmental conditions. The fate of E. coli in the environment is a complex process and is influenced by many factors and their interactions, making it difficult to predict. The findings from this study along with additional studies can be used to improve the accuracy of model predictions to estimate the E. coli loads in watersheds.

Lake Zapotlán is a small (1100 ha) endorheic lake in western Mexico that is internationally recognized by RAMSAR. It receives point source pollution from partially treated sewage from two surrounding cities, as well as non-point sources, including urban runoff, agricultural runoff, erosion and consequent deposition of sediment as a result of deforestation surrounding the Lake. The purpose of this study was to determine the severity of pollution in the Lake through measurement of nutrient and bacteria levels and assess for potential human health and ecological risks in Lake Zapotlán. Results found that nutrient levels have increased since 1994 and that they are high enough to cause eutrophication problems. Partially treated wastewater contributes over 30 tonnes of phosphorus to the Lake each year. E. coli levels were extremely high and could pose a health risk to those participating in recreational activities on the Lake.

Lake Zapotlán is a small (1100 ha) endorheic lake in western Mexico that is internationally recognized by RAMSAR. It receives point source pollution from partially treated sewage from two surrounding cities, as well as non-point sources, including urban runoff, agricultural runoff, erosion and consequent deposition of sediment as a result of deforestation surrounding the Lake. The purpose of this study was to determine the severity of pollution in the Lake through measurement of nutrient and bacteria levels and assess for potential human health and ecological risks in Lake Zapotlán. Results found that nutrient levels have increased since 1994 and that they are high enough to cause eutrophication problems. Partially treated wastewater contributes over 30 tonnes of phosphorus to the Lake each year. E. coli levels were extremely high and could pose a health risk to those participating in recreational activities on the Lake.

Degradation of streams in urban-rural fringe regions occurs through complex interactions between hydrological, physical, chemical and biological mechanisms of the stream environment and surrounding landscape. Biological monitoring using macroinvertebrates may capture the complex and cumulative influences of land activity on the stream environment. The Salmon River catchment in the township of Langley, British Columbia, Canada straddles urban and rural environments in the Lower Fraser Valley. To date the Salmon River catchment has been subject to several environmental surveys. Following these earlier investigations, this study quantified relationships between the stream environment and changing land activity, across multiple scales, from 1975 to 2005, using macroinvertebrates as environmental integrators. Current and historical water, sediment, and macroinvertebrate information along with land use and land-cover evaluations were used to quantify relationships between the macroinvertebrate community and land activity in the catchment. Spatial and seasonal results for specific conductivity (a total dissolved ion indicator) and NO������-N and PO����� (nutrient indicators) traced groundwater and overland inputs to the stream environment. Nitrate guideline exceedances occurred at groundwater-influenced sites. Elevated sediment trace metal concentrations and Zn guideline exceedances occurred mid-reach in the catchment. Peak total macroinvertebrate and sensitive taxa abundance occurred mid-reach in the catchment in 2005, while richness and proportional sensitive abundance peaks were seen at groundwater-influenced sites. The dominance of tolerant to moderately pollution tolerant taxa occurred throughout. Despite historical water quality concerns at groundwater-influenced sites, greater shifts in community composition occurred in headwaters regions. Patterns of land use and land cover changed in sensitive areas (i.e. above aquifer and in the headwaters). A greater number of correlations between land activity and macroinvertebrate measures occurred at streams sites with 100 m buffers. The abundance of sensitive taxa positively correlated with the amount of agricultural land use, while rarefaction declined. Several Macroinvertebrate functional feeding groups correlated positively to forest cover, while sensitive taxa abundance and Zn concentrations declined. Results suggest continued water quality and sediment trace metal concerns, while macroinvertebrate results point to nutrient enrichment and greater historical variability in headwaters regions. Agricultural activity appears to have a stronger influence on aspects of the stream environment despite the presence of urban-rural land activity.

Water quality models are applied to assess the various processes affecting the concentrations of contaminants in a watershed. SPAtially Referenced Regression On Watershed attributes (SPARROW) is a nonlinear regression based approach to predict the fate and transport of contaminants in river basins. In this research SPARROW was applied to the Guadalupe and San Antonio River Basins of Texas to assess E. coli contamination. Since SPARROW relies on the measured records of concentrations of contaminants collected at monitoring stations for the prediction, the effect of the locations and selections of the monitoring stations was analyzed. The results of SPARROW application were studied in detail to evaluate the contribution from the statistically significant sources. For verification of SPARROW application, results were compared to 303 (d) list of Clean Water Act, 2000. Further, a methodology to maintain the monitoring records of the highly contaminated areas in the watersheds was explored with the application of the genetic algorithm. In this study, the importance of the available scale and details of explanatory variables (sources, land-water delivery and reservoir/ stream attenuation factors) in predicting the water quality processes were also analyzed. The effect of uncertainty in the monitored records on SPARROW application was discussed. The application of SPARROW and genetic algorithm were explored to design a monitoring network for the study area. The results of this study show that SPARROW model can be used successfully to predict the pathogen contamination of rivers. Also, SPARROW can be applied to design the monitoring network for the basins.