Impacts of manure management practices on stream microbial loading into Conesus Lake,NY

The microbiology of stream water has a seasonal component that results from both biogeochemical and anthropogenic processes. Analysis of nonevent conditions in streams entering Conesus Lake, NY (USA), indicated that total coliform, Escherichia coli, and Enterococcus spp. levels peak in the summer in all streams, independent of the agricultural use in the stream sub-watershed. Prior to implementation of management practices, E. coli in water draining Graywood Gully, a sub-watershed with 74% of the land in agriculture, reached as high as 2806 CFU/100 mL, exceeding the 235 CFU/100 mL EPA Designated Bathing Beach Standard (EPA-DBBS). In contrast, North McMillan Creek, a sub-watershed with < 13% of its land in agriculture, had E. coli maxima generally near or below the EPA-DBBS. Graywood Gully at times had a higher microbial loading than North McMillan Creek, a sub-watershed 48 times larger in surface area. Over a 5-year study period, there was a major decrease in bacterial loading during nonevent conditions at Graywood Gully, especially after manure management practices were implemented, while bacterial loading was constant or increased in streams draining three other sub-watersheds. E. coli levels dropped more than 10 fold to levels well below the EPA-DBBS while the yearly maximum for Enterococcus dropped by a factor 2.5. Similarly, exceedency curves for both E. coli and Enterococcus also showed improvement since there were fewer days during which minimum standards were exceeded. Even so, Graywood Gully at times continued to be a major contributor of E. coli to Conesus Lake. If wildlife represents a significant source of indicator bacteria to Graywood Gully as has been reported, stream remediation, management efforts and compliance criteria will need to be adjusted accordingly.     

The impact of agricultural best management practices on downstream systems: Soil loss and nutrient chemistry and flux to Conesus Lake,New York,USA

Six small, predominantly agricultural (> 70%) watersheds in the Conesus Lake catchment of New York State, USA, were selected to test the impact of Best Management Practices (BMPs) on mitigation of nonpoint nutrient sources and soil loss from farms to downstream aquatic systems. Over a 5-year period, intensive stream water monitoring and analysis of covariance provided estimates of marginal means of concentration and loading for each year weighted by covariate discharge. Significant reductions in total phosphorus, soluble reactive phosphorus, nitrate, total Kjeldahl nitrogen, and total suspended solids concentration and flux occurred by the second year and third year of implementation. At Graywood Gully, where Whole Farm Planning was practiced and a myriad of structural and cultural BMPs were introduced, we observed the greatest percent reduction (average = 55.8%) and the largest number of significant reductions in analytes (4 out of 5). Both structural and cultural BMPs were observed to have profound effects on nutrient and soil losses. Where fields were left fallow or planted in a vegetative type crop, reductions, especially in nitrate, were observed. Where structural implementation occurred, reductions in total fractions were particularly evident. Where both were applied, major reductions in nutrients and soil occurred. After 5 years of management, nonevent and event concentrations of total suspended solids in streams draining agricultural watersheds were not significantly different from those in a relatively “pristine/reference” watershed. This was not the case for nutrients.     

Quantification of phosphorus sources to a small watershed: A case study of Graywood Gully,Conesus Lake,NY

Phosphorus sources within the Graywood Gully watershed impact water quality within the stream and receiving waters of Conesus Lake, New York. A mass balance approach was instructive in demonstrating the semi-quantitative impact of nonpoint and point nutrient sources on downstream aquatic systems and provided a mechanism to assist in targeting and prioritizing structural best management practices (BMPs) for agricultural areas. The identification and quantification of these sources reveal substantial sources coming from outside the topographic watershed boundary due to the overprint of the built environment on natural surface runoff pathways. The analysis of water sources and phosphorus loading indicated the importance of critical source areas in the watershed and adjacent areas and the effect of the built environment, including drain systems and road ditches, on changing critical hydrological pathways. The impact of BMPs within the watershed was masked by the external contributions from the “extended” watershed, adding over 40% of the total P load to Conesus Lake. This result suggests that the lack of significant decrease in dissolved phosphorus observed in the heavily managed Graywood sub-watershed is a result of not considering the “extended” watershed.     

Detecting effects of Best Management Practices on rain events generating nonpoint source pollution in agricultural watersheds using a physically-based stratagem

Nonpoint source pollution (NPSP) is the export to receiving waters of nutrients originating from diffuse sources. This research documents a methodology for confirming reductions in NPSP resulting from implementation of agricultural Best Management Practices (BMPs). It employs that methodology to confirm the success of BMPs implemented in Graywood Gully, a study sub-watershed that drains into Conesus Lake, NY. Evaluating the effects of BMPs in agricultural watersheds is often complicated by significant temporal variability in weather and hydrologic conditions. In many cases NPSP demonstrates much greater variability in response to antecedent hydrologic/meteorologic conditions than to commonly implemented BMPs. In essence, weather variability can mask the beneficial effects of the BMPs. By using the Thornthwaite–Mather procedure to model soil moisture status in addition to event rainfall total, it is possible to remove the major sources of weather/hydrologic-related variability, essentially reducing the number of experimental variables to the BMP itself. Application of this method to the Graywood sub-watershed reveals that BMPs can greatly reduce export of NPSP generated pollutants to receiving waters. Estimates of NPSP reductions range from 53% for soluble reactive phosphorus to 89% for nitrate.     

Winter application of manure on an agricultural watershed and its impact on downstream nutrient fluxes

Whole Farm Planning was instituted and monitored over a 5-year period within the Graywood Gully sub-watershed of Conesus Lake, NY (USA). An array of agricultural Best Management Practices (BMPs) (strip cropping, fertilizer reduction, tiling, manure disposal practices, etc.) were simultaneously introduced to determine the impact of a concentrated management effort on nutrient and soil loss from one watershed within the Conesus Lake catchment. During the study period, significant decreases in winter concentrations of dissolved and particulate fractions, including total phosphorus (TP), soluble reactive phosphorus (SRP), total Kjeldahl nitrogen (TKN), and nitrate (NO₃) but not total suspended solids (TSS), were observed. These decreases may or may not be attributed to cessation of manuring practices. Three years into the study, an opportunity existed to test the responsiveness of the watershed to the curtailment of a single BMP — winter manure application to fields. We field-tested the hypothesis that a change in winter manure applications would impact dissolved and particulate fractions in stream water draining this watershed. We found that the water quality of Graywood Gully is very responsive to winter manure application on environmentally sensitive portions of the sub-watershed. With the short-term resumption of manure application, TP, SRP, TKN, and NO₃ concentrations rose dramatically in stream water; elevated phosphorus concentrations persisted over a 5-week period. Total suspended solids, however, were not elevated after short-term manure application. Factors that affected these results were slope of the land, application of manure over snow and during a snowfall, warm air and soil temperatures, and possibly tile drainage of snowmelt water. Managers of agricultural systems must recognize that phosphorus losses from the watershed during the nongrowing season may detrimentally affect nuisance population of algae in lakes during the summer.     

In situ experimental studies of Eurasian Watermilfoil (Myriophyllum spicatum) downstream from agricultural watersheds: Nutrient loading,foliar uptake,and growth

Recent studies in Conesus Lake, New York, documented significant decreases in the biomass of Eurasian watermilfoil (Myriophyllum spicatum) near the mouths of streams draining sub-watersheds where reductions in nutrient loading occurred as a result of the implementation of agricultural Best Management Practices (BMPs). In situ experiments were conducted to further investigate the relationship between stream loading, foliar uptake, and growth of Eurasian watermilfoil. In two of three experiments, plants cropped to a height of approximately 50 cm had the lowest growth (g/m²) downstream from a sub-watershed where major BMPs had been implemented (80% and 0%). In sub-watersheds where minimal or no BMPs were introduced, plants showed significantly higher growth as biomass increased (216% and 22%). In a second set of experiments, shoots of Eurasian watermilfoil plants were incubated for 24 h in ambient lake water and in lake water with enriched concentrations of nitrate and soluble reactive phosphorus comparable to rain event stream effluent concentrations and then allowed to grow in situ for a 2-week experimental period. For all experiments combined, the shoot biomass increased significantly in the enhanced nutrient treatments when compared to the ambient treatment at the Sand Point macrophyte bed (reduced loading) but not at the Eagle Point macrophyte bed (high loading). Overall, the results indicate that foliar uptake of nutrients in stream effluent can contribute to the growth of Eurasian watermilfoil and reinforce the hypothesis that reductions in stream loading through agricultural BMPs can help reduce macrophyte growth in the lake littoral.     

Microbial Pollution Characterization at a TMDL Site in Michigan: Effect of Hydrological Conditions on Pollution Loading

Communities throughout the United States are developing and implementing watershed management plans to address nonpoint sources of pollution and meet Total Maximum Daily Load (TMDL) requirements. Once a TMDL is established, a watershed management plan is developed and implemented to reduce contaminant sources and attain TMDL goals. Developing an effective TMDL and remediation plan should take into account fluctuation of pollution loadings and the timing of first-flush events. The objective of this study is to investigate the effect of hydrological conditions on microbial pollutant levels at a TMDL site during spring and summer storm events. A total of 64 water samples were collected from Sloan Creek in mid-Michigan in the spring/summer of 2015. All samples were analyzed to quantify concentrations of E. coli, bovine-associated Bacteroides (BoBac) gene markers, and human-associated Bacteroides (HuBac) gene markers. Discharge was the driving force of microbial contaminant loading in the studied water body. E. coli concentrations had significant strong correlation with precipitation and discharge, and BoBac concentrations were positively related to discharge. E. coli, BoBac and HuBac patterns suggested first-flush phenomena occurred during summer storms. E. coli permit exceedance rates increased from 31% before first-flush, to 100% during and after first-flush in the summer. The resulting information may help develop a plan for restoring impaired waters and establish the maximum amount of pollutants that the body of water can receive during different hydrological conditions.     

Escherichia coli survival and transfer in estuarine bed sediments

Bed sediment resuspension is a potential source of faecal microorganisms in the water column of estuaries. As such, it is important to identify the survival of faecal microorganisms in these bed sediments and understand how bed sediment resuspension impacts the quality of estuarine waters. This study explores the effect of bed sediment resuspension on Escherichia coli concentrations in the water column and the persistence of E. coli in the water column and bed sediments of the Yarra River estuary in South‐Eastern Australia. Using sediment cores, we identified that the resuspension of both surficial sediments (e.g., by tidal movements) and deeper bed sediments (e.g., by large storm events) can increase E. coli concentrations in the water column by up to 20 times in estuaries in oceanic climates. Bed sediment resuspension can result in increased E. coli concentrations in the water column even up to 24 days after E. coli first enters the estuarine water. This study demonstrates that faecal microorganisms, such as E. coli, can persist for extended periods in estuarine bed sediments, which may then be re‐entrained into the water column via recreational activities, high flow events, or tidal fluctuations. If the survival and resuspension processes observed here hold true for pathogenic microorganisms, the resuspension of bed sediments may indeed represent an increased public health risk.     

Agricultural best management practices for Conesus Lake: The role of extension and soil/water conservation districts

Small sub-watersheds of the Conesus Lake catchment were the site of a project evaluating the ability of agricultural Best Management Practices (BMPs) to maintain soil and nutrients on the landscape and to reduce the impact of agriculture on downstream aquatic systems. Local agricultural agencies, with participation of local farmers, joined with scientists to focus attention on watershed issues, to develop and foster a sense of stewardship among the farming community, and to assist and coordinate collaboration among academic researchers, governing bodies, and the agricultural community. Cornell Cooperative Extension served as a liaison and as a resource and assisted in the development and implementation of voluntary BMPs in selected sub-watersheds of Conesus Lake. We discuss our approach to working with producers, the selection of watersheds for management, and our decision-making process for implementation of BMPs. Decisions to establish traditional structural and nonstructural management practices on sub-watersheds of Conesus Lake were based on field assessments, soil testing, the Phosphorus Index, and the software package Cornell Cropware. For example, the use of soil testing and the Cornell Cropware software allowed the cooperating farms to apply fertilizer only as needed for optimum crop production. Farmers achieved cost savings because previous plans had not given enough credit to soil reserves, manure, and sod crop nutrients. Low-cost voluntary practices based on well-established agricultural management practices have been combined with cost-shared (structural) practices in Conesus Lake watersheds to mitigate the impact of agricultural runoff on water quality and to improve cost efficiency of agricultural operations.     

Management of agricultural practices results in declines of filamentous algae in the lake littoral

Filamentous algal cover was quantified during periods of peak biomass from 2001 to 2007 in six littoral macrophyte beds in Conesus Lake, New York (USA). Three of the study sites were adjacent to streams that drained sub-watersheds where extensive agricultural best management practices (BMPs) designed to reduce nutrient runoff were implemented beginning in 2003. Three other study sites were downstream from sub-watersheds where only a few or no BMPs were implemented by landowners. For the sites that received extensive management, comparisons of the Pre-BMP baseline period (2–3 yrs) to the Post-BMP period (4 yrs) revealed that algal cover was statistically lower than baseline in eight of eleven years (72.7%). For the three sites where limited or no management was implemented, the percent cover of filamentous algae was lower than Pre-BMP baseline levels in only three of twelve years (25%). Where major reductions in cover of filamentous algae occurred, positive relationships existed with summer stream loading of nitrate and soluble reactive phosphorus to the nearshore. In some cases only nitrate loading was significantly correlated with percent cover, indicating that the relative importance of nitrogen and phosphorus to algal growth near streams may be determined by the characteristics and land use within each sub-watershed. Agricultural BMPs targeting nutrient and suspended solid runoff can effectively reduce filamentous algal growth locally along the lake littoral zone on a time scale of months to a few years and with moderate commitment of resources. This work offers a new perspective for management of the growing problem of littoral algal growth in the embayments and drowned river mouths of the Great Lakes.     

Modelling of nearshore microbial water quality at confluence of a local tributary in Lake St. Clair

Microbial water quality, measured as Escherichia coli (E. coli) concentration, at beaches along the southern shore of Lake St. Clair in Canada, often exceeds public safety guidelines. Belle River, located near a public beach and a drinking water intake, is one of the several smaller tributaries of the lake whose contribution to nearshore microbial water quality is currently unknown. A flexible mesh 3D coupled TUFLOW-FV and Aquatic Ecodynamic (AED2+) model was used to simulate the hydrodynamics and microbial water quality in Lake St. Clair. A higher resolution nested model was developed within the lake-wide TUFLOW-FV model for better spatial and temporal resolution in the local region surrounding Belle River. Regular and up to a factor of four difference in predicted E. coli concentrations were observed with the nested and lake-wide models at the public beach next to Belle River, whereas the difference was marginal at the drinking water intake about a kilometre away from the shore. While the E. coli loading to Lake St. Clair from Belle River is considered negligible, >90% of the predicted daily E. coli concentration at the beach and > 50 % at the water intake were attributed to Belle River from amongst all watershed sources to Lake St. Clair considered in the model. The model results also show that the construction of a new 150 m jetty in 2018, replacing the older 25 m jetty separating Belle River from the public beach, is expected to significantly reduce E. coli concentrations observed at the beach.     

Seasonal variation in the influence of environmental drivers on nearshore water quality along an urban northern Lake Ontario shoreline

We examined drivers of water quality during 2007–2013 in a region of Lake Ontario influenced by various anthropogenic inputs and natural influences. Nutrient concentrations generally declined from shoreline to offshore, with mean concentrations approaching background after 1 km from shore. N species were an exception to this overall pattern, often with higher concentrations coincident with a mid-nearshore Water Pollution Control Plant outfall (WPCPo). The WPCPo, however, did not appear to be a major contributor to shoreline total phosphorus (TP) or ammonia + ammonium. Shoreline TP variability increased in dry years, while E. coli and conductivity variability increased in wet years. The influence of environmental drivers on water quality differed seasonally. In summer, cross-shore winds causing resuspension appeared to be drivers of elevated nearshore TP and suspended solids (SS), while precipitation, light, and water column stability were related to E. coli. Summer biological activity was evident in higher shoreline total Kjeldhal N contributions and lower NO₃ + NO₂ and dissolved inorganic N. In fall and spring, TP, SS, and conductivity were elevated within 400 m of the shore, suggesting tributary inputs were an important P delivery mechanism to the nearshore in addition to spring resuspension events. Fall, however, represented a transitional period representing a shift from drivers dominant in summer to those in spring. The analytical approach used here reveals generalizable patterns in nearshore water quality and their drivers and may be applicable to other regions where there is a confluence of varying drivers of water quality to a nearshore region.     

Nonpoint source reduction to the nearshore zone via watershed management practices: Nutrient fluxes,fate, transport and biotic responses — Background and objectives

Studies that evaluate the linkages between watershed improvement through Best Management Practices (BMPs) and downstream outcomes are few. Water quality of coastal waters is often impacted by soil and nutrient loss from watersheds in agriculture. Mitigation of these impacts is of concern in the Great Lakes, the Finger Lakes Region of New York State, and generally in water bodies of North America. In this issue, we report on hypothesis-based research at the watershed level evaluating the impact of BMPs on mitigation of nonpoint sources of nutrient and soil loss to streams and the nearshore zone of a lake. Specifically, we hypothesize not only reductions in nutrient and soil losses from watersheds but also a resultant decrease in metaphyton (filamentous algae), coliform bacteria, and macrophyte populations in the nearshore at stream mouths draining sub-watersheds where BMPs were introduced. Small experimental sub-watersheds, predominantly in agriculture (> 70%), were selected to ensure that effects on downstream systems would not be confounded by other land use practices often observed in large watershed approaches. In this introductory paper, we provide background information on Conesus Lake, its watershed, and the Conesus Lake watershed project, a large multi-disciplinary study evaluating agricultural management practices. The series of papers in this volume consider the effect of BMPs designed to control nonpoint sources on water chemistry, metaphyton, macrophytes, and microbial populations in the coastal zone of a lake. Ultimately, this volume expands the basic understanding of the ability of BMPs to control nonpoint source pollution while contributing toward the goal of improving water quality of downstream systems including streams, embayments, and the nearshore of large lakes.     

Responses of lake macrophyte beds dominated by Eurasian watermilfoil (Myriophyllum spicatum) to best management practices in agricultural sub-watersheds: Declines in biomass but not species dominance

Long-term studies of macrophyte beds growing near streams in Conesus Lake, New York, have revealed a high biomass and continuing dominance of the invasive rooted species Eurasian watermilfoil (Myriophyllum spicatum). We tested whether agricultural best management practices (BMPs) designed to reduce tributary nutrient and soil loss from the watershed could reduce populations of Eurasian watermilfoil downstream in the lake littoral. Six macrophyte beds were monitored during a 3-year baseline period (2001–2003) prior to the implementation of BMPs and for a 4-year experimental period after a variety of agricultural BMPs were implemented in three sub-watersheds. For three macrophyte beds downstream from sub-watersheds managed as part of our project, quadrat biomass decreased by 30–50% and was statistically lower than Pre-BMP baseline values in 7 of 11 experimental sample years. Biomass loss primarily in the form of the dominant Eurasian watermilfoil ranged from 6.2 to 10 t wet weight for each bed. The declines in biomass coincided with significant annual and January–August decreases in the concentrations and fluxes of dissolved nutrients, total phosphorus, and total suspended solids in nearby streams. For three macrophyte beds downstream from watersheds in which landowners applied less extensive or no new agricultural management, biomass was statistically indistinguishable from Pre-BMP baseline values in all 12 experimental sample years. Milfoil remained the overwhelmingly dominant species at all sites during the entire study period. These results provide impetus for the use of watershed nutrient management to control the nuisance growth of Eurasian watermilfoil on a local scale in the lake littoral.     

Fecal indicator organism density in beach sands: Impact of sediment grain size,uniformity, and hydrologic factors on surface water loading

Fecal loading to beach sands and subsequent transport to surface water may result in the degradation of surface water quality. To better understand the relationship between Escherichia coli in sands, beach hydrology, and recreational water quality, we collected surface water, groundwater, and sand samples from three Lake Michigan beaches with varying substrates (fine sand to pebbles, July 2005–June 2006). Sediment cores collected within transects perpendicular to and at fixed distances from the shoreline (0 m, 10 m, 20 m) and surface water samples collected at a depth of 1 m were analyzed for E. coli. Grain size analysis was performed on duplicate core samples to assess the relationship between E. coli density and mean grain size and uniformity. Groundwater samples, collected from shallow drive-point piezometers within the test area, were also analyzed for E. coli. E. coli density in beach sands differed significantly with distance from shore with the highest density occurring at the berm crest (0 m). Mean grain size and uniformity accounted for variation in E. coli density with fine sand of uniform distribution having the highest content. E. coli density in surface water was correlated to E. coli density in beach sand samples at the berm crest. E. coli in groundwater was < 10 to 579 MPN/100 ml (2005); none was detected in 2006. Management interventions, including altered beach grooming practices and slope assessments, may be effective in reducing E. coli content at beaches comprised of fine sands of uniform grain size, hence reducing water quality advisories.     

Heatwaves and storms contribute to degraded water quality conditions in the nearshore of Lake Ontario

As extreme climatic events, such as heatwaves and storms, become more frequent in response to changing climates, understanding the role climatic events play on water quality is essential. Here, we use water quality monitoring data collected from the nearshore of Lake Ontario between 2000 and 2018 to ask: i) which sites in the nearshore of Lake Ontario have statistically extreme water quality conditions?; ii) do water quality conditions differ in extreme versus non-extreme climate years?; and iii) what are the significant antecedent extreme weather drivers of water quality in the nearshore of Lake Ontario? Three sites with the highest chlorophyll a concentrations and eutrophic conditions, two of which are in Areas of Concern, exhibited the strongest responses to climate extremes. Antecedent weather conditions explained 87.2% of the variation in extreme chlorophyll a concentrations. In particular, warmer temperatures and heatwaves corresponded with statistical extremes in chlorophyll a concentrations. Precipitation accounted for 35.5% of the variation in extreme conditions of turbidity, including storm events the day prior to sampling. When considering site-specific extreme conditions, antecedent weather conditions explained 66.8% of the variation in turbidity. We illustrate the strong role that heatwaves and storm events play on spatial and temporal patterns in extreme water quality conditions, highlighting the importance of incorporating climate change adaptation plans into ecosystem management strategies to preserve water quality in the highly important and iconic nearshore regions of the Laurentian Great Lakes.     

Spatial and temporal distribution of the cyanotoxin microcystin-LR in the Lake Ontario ecosystem: Coastal embayments,rivers, nearshore and offshore,and upland lakes

Cyanotoxins, a group of hepatotoxins and neurotoxins produced by cyanobacteria, pose a health risk to those who use surface waters as sources for drinking water and for recreation. Little is known about the spatial and seasonal occurrence of cyanotoxins in Lake Ontario and other lakes and ponds within its watershed. Within the embayments, ponds, rivers, creeks, shoreside, and nearshore and offshore sites of Lake Ontario, microcystin-LR concentrations were low in May, increased through the summer, and reached a peak in September before decreasing in October. Considerable variability in microcystin-LR concentrations existed between and within habitat types within the Lake Ontario ecosystem. In general, the average microcystin-LR concentration was two orders of magnitude lower in embayment (mean = 0.084 μg/L), river (mean = 0.020 μg/L), and shoreside (mean = 0.052 μg/L) sites compared to upland lakes and ponds (mean = 1.136 μg/L). Concentrations in the nearshore sites (30-m depth) and offshore sites (100-m depth) were another order of magnitude lower (mean = 0.006 μg/L) than in the creek/river, bay/pond, and shoreside habitats. Only 0.3% (2 of 581) of the samples taken in Lake Ontario coastal waters exceeded the World Health Organization (WHO) Drinking Water Guideline of 1 μg microcystin/L for humans. In contrast, 20.4% (20 of 98) of the samples taken at upland lakes and ponds within the watershed of Lake Ontario exceeded WHO Guidelines. No significant relationship between nitrate and microcystin-LR concentrations was observed in Lake Ontario even though a significant positive relationship existed between phosphorus and phycocyanin and microcystin-LR concentrations. At an upland lake site (Conesus Lake) in the Ontario watershed, the development of a littoral Microcystis population was not observed despite high nutrient loading (P and N) into the nearshore zone, well-developed nearshore populations of filamentous Spirogyra and Zygnema, the occurrence of Dreissena spp., and the known occurrence of Microcystis and microcystin production in the pelagic waters of Conesus Lake.     

System design and treatment efficiency of a surface flow constructed wetland receiving runoff impacted stream water

This study reported the efficiency of a free water surface flow constructed wetland (CW) system that receives runoff impacted stream water from a forested and agricultural watershed. Investigations were conducted to examine the potential effect of hydraulic fluctuations on the CW as a result of storm events and the changes in water quality along the flow path of the CW. Based on the results, the incoming pollutant concentrations were increased during storm events and greater at the near end of the storm than at the initial time of storm. A similar trend was observed to the concentrations exiting the CW due to the wetland being a relatively small percentage of the watershed (<0.1%) that allowed delays in runoff time during storm events. The concentrations of most pollutants were significantly reduced (p < 0.05) except for nitrate (p = 0.5). Overall, this study suggests that the design of the system could feasibly function for the retention of most pollutants during storm events as the actual water quality of the outflow was significantly better by 21-71% than the inflow and the levels of pollutants were reduced to appreciable levels.     

Characteristics of nearshore water quality of Lake Ontario coast under Credit Valley Conservation Jurisdiction,Ontario, Canada

The 28.5 km Lake Ontario shoreline along Credit Valley Conservation’s jurisdiction is habitat for native flora and fauna, the source of drinking water for over two million residents, and the location of outfalls for Region of Peel’s two wastewater treatment plants. Some of the significant sources of pollutants to this region are urban tributaries and the Credit River. Instream, shoreside, and nearshore water quality of this region were characterized under this Lake Ontario Integrated Shoreline Strategy study. Eight Parameters of Concern (PoC); water temperature (WT), total suspended solids (TSS), total phosphorous (TP), orthophosphate (OP), nitrate-nitrogen (NO₃-N), Escherichia coli (E. coli), specific conductivity (SC), and pH were studied from 2011 to 2013. Amongst all the PoCs TP was of concern since its instream (75th percentile range: 51.0 µg/L to 188 µg/L), shoreside (75th percentile range: 9.00 µg/L to 53.75 µg/L), and nearshore (75th percentile range: 9.75 µg/L to 19.00 µg/L) concentrations, exceeded their respective objectives of 30 µg/L and 10 µg/L. Other parameters in shoreside/nearshore samples met their respective provincial/federal objectives/guidelines; however, instream E. coli and specific conductivity levels were elevated, reflecting the effects of urbanization. The Lake water temperature moorings recorded lake stratification dynamics, including eight downwelling and five upwelling events during 2011 deployment period. These results provide baseline data for future climate change-related assessment studies.     

Effect of hydrological and geophysical factors on formation of standing water and FIB reservoirs at a Lake Michigan beach

Water quality impairment of Great Lakes beaches is caused by fecal pollution from point and nonpoint sources. Erosion due to wind or wave action, invasive vegetation and chronically wet, flooded or standing water are conditions that can magnify water quality problems at beaches. We investigated the hydrological and geophysical characteristics of the Bradford Beach on Lake Michigan (Milwaukee, WI) and the linkage between standing water and persistent contamination by fecal indicator bacteria (FIB). Our study showed that there is a positive correlation between high concentrations of Escherichia coli (E. coli) in sand and high moisture content caused by standing water. The main factor associated with the formation of standing water was rainfall. There were also notable differences in standing water and/or wet sand conditions in the northern and southern parts of the beach. These differences could be accounted for by differences in ground water elevations and beach erosion and accretion patterns. Other important physical features of the beach were the presence of rain gardens and mean grain diameter (d₅₀). Rain gardens above the beach face that capture runoff contributed to transient increases in the water table, facilitating standing water formation. Standing water, stormwater runoff infiltrating through the sand and into groundwater as well as wave run up that delivered contaminated surface water to the back beach area were of health concern following heavy rainfall events. The outcomes of this study will likely be useful to beach managers investigating mechanisms/sources of fecal indicator bacteria loading and potential mitigative approaches.