Nottawasaga River Research Articles

Assessing the Native Plant Species for Phytoremediation of Freshwater Bodies in Southern Ontario, Canada

Many Canadian freshwater ecosystems are polluted by agricultural runoff, impairing their function with increased nutrient levels. Here, we simulated the water filtration function of wetlands, which uses aquatic plant species to create a phytoremediation system that can address the contamination of freshwater ecosystems with excess nutrients. We collected the water samples from three of Ontario’s freshwater bodies: the Holland Marsh, a highly agricultural area; the Nottawasaga River, a river in a rural area and part of a greater Nottawasaga watershed and Lake Ontario, near industrial sites in the Niagara region. To filter nitrogen (N), phosphorus (P) and potassium (K) from the collected samples, we determined the effectiveness of five local wetland and agricultural plant species: duckweed (Lemnoideae), watercress (Nasturtium officinale), coontail (Ceratophyllum demersum), thyme (Thymus praecox) and parsley (Petroselinum crispum). During a five-month experiment, plants were grown in collected water samples to determine their ability to uptake N, P and K. Along with monitoring their effectiveness in lowering nutrient levels, we tracked the health and growth of each plant species. The results showed that duckweed was the most tolerant to high nutrient concentrations and the most effective at overall nutrient reduction. From the Holland Marsh sample with the highest nutrient concentrations among all collected samples, the duckweed reduced N, P, and K by 11%, 53%, and 21%, respectively, compared to the control sample (i.e., with no plant). This filtration system allows for ecosystem restoration and prevention of further damage and contamination from agricultural runoff and nutrient pollution.

Modeling River Plume Dynamics in a Large Wind-Forced Embayment

Water quality degradation, in the form of undesirable algae, occurs near the Nottawasaga River mouth and along Wasaga Beach, southeastern Georgian Bay. The ability to manage this water resource is compromised due to lack of monitoring and science. In the present study, a 3D hydrodynamic model was applied to gain an understanding of how advection and dilution of the river plume can trap nutrients along Wasaga Beach. Simulated water temperatures and currents had a root-mean-square error between 1.5°C and 2.5°C and ∼0.06 m s−1, respectively. Maximum nearshore river concentrations occurred near the beach during high river discharge >20 m3 s−1 and westerly winds. Generally, the river plume was advected by winds >∼4 m s−1, traveling along the northern shoreline during southerly winds and along the southwest shoreline during northeasterly winds. This process was analytically modeled when the wind strength indicator or Froude number (ratio of the characteristic wind-velocity scale to the buoyancy–velocity scale) was greater than one.

Riverine transport and nutrient inputs affect phytoplankton communities in a coastal embayment

Abstract Rivers often transport phytoplankton to coastal embayments and introduce nutrients that can enrich coastal plankton communities. We investigated the effects of the Nottawasaga River on the nearshore (i.e. within 500 μm of shore) phytoplankton composition along a 10‐km transect of Nottawasaga Bay, Lake Huron in 2015 and 2016. Imaging flow cytometry was used to identify and enumerate algal taxa, which were resolved at sizes larger than small nanoplankton (i.e. >5 μm). Multivariate analysis (perMANOVA and redundancy analysis) and a dilution model were used to examine how nutrients and the transport of algal taxa affected community composition in the bay. Sampling stations with different percentages of river water had significantly different phytoplankton communities. Phytoplankton community composition was also strongly associated with nutrients, including total phosphorus, which also varied with the percentage of river water. The majority of the 51 phytoplankton taxa identified in 2016 had numerical abundances in the bay that could be explained simply by the dilution of incoming river water. Phytoplankton transported from the river had a higher proportion of edible‐sized cells (<30 μm), particularly in summer when colonial cyanobacteria were numerically dominant in the bay. Six taxa were more abundant than expected from the dilution of river water and included some cyanobacteria with late summer maxima. Five of the taxa that were transported from the river were less abundant than expected in the bay. Whereas impacts of fertilisation due to the characteristically higher nutrient concentration in the river are to be expected, the strong and highly correlated effects of transport within the narrow coastal band of this study largely concealed any distinct fertilisation effects. Riverine inputs may strongly influence the nearshore assemblage of phytoplankton in oligotrophic embayments in large lakes, creating hotspots for productivity, species turnover, and trophic dynamics.

Landscape characteristics driving spatial variation in total phosphorus and sediment loading from sub-watersheds of the Nottawasaga River, Ontario

Eutrophication from agricultural runoff is a global problem, often resulting in formation of anoxic zones in receiving water bodies. The Nottawasaga River Watershed (NRW) is dominated by agricultural land-use, and drains into Nottawasaga Bay, Georgian Bay (Lake Huron). A fundamental feature of the NRW is the Minesing Wetlands, a Ramsar site and the largest inland wetland in southern Ontario. We used total phosphorus (TP) concentration-discharge relationships to estimate annual loading from six sub-watersheds and compared these against published models, which did not offer a way to account for the unique properties of the Minesing Wetlands. We developed predictive loading models specifically for the NRW to account for these characteristics, which accurately predict daily summer base-flow TP (r2 = 0.76, p = <0.0001) and total suspended solids (TSS; r2 = 0.65, p = <0.0001) loads for 11 subwatersheds using geomorphic and land-cover variables. Drainage area and % pasture land were the most significant predictive variables driving spatial variability in TP and TSS loading rates among subwatersheds. The positive relationship between TP and % wetland (r2 = 0.22, p = 0.0063) also suggested that the Minesing Wetlands are a source of nutrients to the Nottawasaga River. Watershed geomorphology (e.g. slope) was a good predictor of land cover, and produced accurate loading estimates. This study is the first to offer a new approach to predict TP and TSS loading rates during the growing season using readily available geospatial data.

Stratigraphic analysis of Late Wisconsin and Holocene glaciolacustrine deposits exposed along the Nottawasaga River, southern Ontario, Canada

Analysis of 56 outcrop exposures in cut banks along the Nottawasaga River in southern Simcoe County, Ontario, Canada, has led to the identification of eight stratigraphic units (SU1–SU8) that represent a record of changing environmental conditions during deglaciation and exhibit strong controls on shallow groundwater flow in the region. The stratigraphic succession is floored by the Late Wisconsin Newmarket Till (SU1), which is locally overlain by ice-proximal debris flow deposits (SU2). These glacial sediments are overlain by glaciolacustrine silt rhythmites (SU3) that pass upwards into deltaic sand (SU4) and channelized fluviodeltaic sand and gravel (SU5). Lying above the fluvial deposits are widespread interbedded glaciolacustrine sands and silt (SU6), which coarsen up-section toward the ground surface. The succession is locally capped by fluviodeltaic (SU7) and younger fluvial (SU8) deposits. These SUs record sedimentary environments that existed during deglaciation of the region and provide insight into the evolution of glacial lakes Schomberg and Algonquin and the Nipissing phase of the upper Great Lakes. The environmental changes described from sediments along the Nottawasaga River provide insights into basin-scale events that occurred throughout the upper Great Lakes during deglaciation. Qualitative observations of groundwater discharge from sediments at outcrop faces are used to characterize the hydraulic function of the stratigraphic units as well as possible preferential groundwater flow pathways in the shallow subsurface.

Artificial Sweeteners Reveal Septic System Effluent in Rural Groundwater.

It has been widely documented that municipal wastewater treatment plant effluents are a major source of artificial sweeteners to surface waters. However, in rural areas, the extent to which septic systems contribute these same compounds to groundwater aquifers is largely unknown. We examined the occurrence of four commonly used artificial sweeteners in an unconfined sand aquifer that serves as a water supply for rural residents, as a receptor of domestic wastewater from septic systems, and as a source of baseflow to the Nottawasaga River, ON, Canada. Groundwater from the Lake Algonquin Sand Aquifer in the southern Nottawasaga River Watershed was collected from private domestic wells and as groundwater seeps discharging along the banks of the Nottawasaga River. Approximately 30% of samples had detectable levels of one or more artificial sweeteners, indicating the presence of water derived from septic system effluent. Using acesulfame concentrations to estimate the fraction of septic effluent in groundwater samples, ∼3.4 to 13.6% of the domestic wells had 1% or more of their well water being derived from septic system effluent. Similarly, 2.0 to 4.7% of the groundwater seeps had a septic effluent contribution of 1% or more. No relationship was found between the concentration of acesulfame and the concentration of nitrate, ammonium, or soluble reactive phosphorus in the groundwater, indicating that septic effluent is not the dominant source of nutrients in the aquifer. It is expected that the occurrence of artificial sweeteners in shallow groundwater is widespread throughout rural areas in Canada.

Contribution of phosphorus to Georgian Bay from groundwater of a coastal beach town with decommissioned septic systems

Abstract Groundwater inputs of phosphorus (P) to the Laurentian Great Lakes are poorly known, but may contribute to eutrophication and algal bloom issues. This study's objective was to assess the contribution of P to Nottawasaga Bay from the surficial sand aquifer at Wasaga Beach, representing a coastal cottage area with decommissioned septic systems, and how this might change with time. The first part of the study involved site-scale groundwater sampling beside 4 provincial park public washrooms. Legacy P plumes were detected at two of these sites, with one being > 30 years since decommissioning. P transport calculations including sorption onto aquifer sediments indicate the majority of P plumes from the town's decommissioned septic systems have likely not yet reached the shoreline, > 50 years since installation, and will likely contribute P to the bay for many decades. The second part of the study consisted of broader-scale (town-wide) surveys of shallow beach groundwater. Dissolved P concentrations were ~ 50 μg/L for background groundwater (in town and reference area), which is similar to literature values. This P may have been sourced from degrading organic matter, bird droppings, or soil-aquifer minerals. Sporadic elevated concentrations up to 420 μg/L may be from legacy septic systems and/or natural sources. A rough calculation suggests groundwater P loading along Nottawasaga Bay's eastern shore (Wasaga Beach, 10-km; adjacent similar beaches, 40-km) is a few percent at most of that from the Nottawasaga River. Thus, it more likely affects localized periphyton and macrophyte growth rather than significantly affecting the Nottawasaga Bay P budget.

Glyphosate residues in rural groundwater, Nottawasaga River Watershed, Ontario, Canada.

The objective of this study was to investigate the occurrence of glyphosate residues (glyphosate and its metabolite AMPA) in shallow groundwater in a catchment dominated by agriculture, and to examine the potential for this groundwater to store and transmit these compounds to surface waters. Glyphosate residues were found in some of the groundwater samples collected in riparian (surface seeps), upland (mostly <20 m below ground) and wetland settings (<3 m below ground). Overall, glyphosate and AMPA were detected in 10.5 and 5.0%, respectively, of the groundwater samples analyzed as part of this study. All concentrations of glyphosate were well below Canadian guidelines for drinking water quality and for protection of aquatic life. Seasonal differences in concentrations in riparian seeps were possibly related to cycles of weather, herbicide application and degradation of glyphosate. Highest concentrations were at upland sites (663 ng L(-1) of glyphosate, 698 ng L(-1) of AMPA), apparently related to localized applications. Most glyphosate detections in wetlands were >0.5 km distant from possible areas of application, and, combined with other factors, suggest an atmospheric transport and deposition delivery mechanism. In both upland and wetland settings, highest glyphosate concentrations were sometimes not at the shallowest depths, indicating influence of hydrological factors. The glyphosate/AMPA detections in riparian seeps demonstrated that these compounds are persistent enough to allow groundwater to store and transmit glyphosate residues to surface waters. Detections in the wetlands support earlier evidence that atmospheric transport and deposition may lead to glyphosate contamination of environments not intended as targets of applications. This interpretation is further supported by detections of both glyphosate and AMPA in precipitation samples collected in the same watershed. © 2016 Her Majesty the Queen in Right of Canada Pest Management Science © 2016 Society of Chemical Industry.

Assessing the performance of a semi‐distributed hydrological model under various watershed discretization schemes

AbstractPhysically based distributed and semi‐distributed hydrological models have become some of the primary tools for water resources studies and management over the past decades owing to increased computational capabilities and advances in data measurements. Representation of the existing heterogeneity in nature still remains one of the main challenges in these models and is accomplished primarily via watershed discretization, subdividing watersheds into hydrologically similar land parcels. Discretization decisions in distributed modelling studies are often ad hoc and determined with little or no quantitative analysis to support these decisions. In this work, we present a quantitative methodology for assessing alternative watershed discretization schemes in terms of their corresponding model performance in ungauged basins. The effect of the computational time spent for calibrating each scheme (calibration budget) is considered as part of the assessment. Here, these schemes differ in how they represent landscape attributes and range from a simple lumped scheme to more complex ones by adding spatial land cover and then soil information. The methodology is demonstrated using the Modélisation Environmentale–Surface et Hydrologie (MESH) model as applied to the Nottawasaga River basin in Ontario, Canada. Results reveal that model performance in ungauged basins depends upon the location of the validation sub‐basin (i.e. upstream or downstream) with respect to the calibration sub‐basins. Also, using a more complex scheme did not necessarily lead to improved performance in validation, when constrained by calibration budget. Therefore, the calibration budget also should be considered as a factor in the assessment process. This methodology was also implemented using a shorter sub‐period for calibration, which leads to substantial computational saving. Results of the sub‐period test were promising and consistent particularly when sufficient budget is spent to calibrate the model. Other strategies utilized for reducing the computational burden of the proposed analyses are also discussed in this study. Copyright © 2015 John Wiley &amp; Sons, Ltd.

The Scene of its Achievement

This article examines the debate over the ownership and preservation of an artefact of the War of 1812-14: the wrecked hull of the schooner HMS Nancy, which was discovered and raised at the mouth of the Nottawasaga River in Wasaga Beach, Ontario, in the summer of 1925. The discovery precipitated a vigorous struggle for control of the artefact that pitted local historical enthusiasts and politicians against the government of Ontario and its representatives. The crux of the debate concerned where best to store and house the hull. The government initially intended to remove the Nancy’s remains to Toronto where, officials argued, the vessel could best enjoy the status of a truly national icon, while an organized group from the Nottawasaga region charged that the artefact should remain in the place it perished as the best way to honour its historical significance as a symbol of British-Canadian nationhood and to make use of its value as a tourist attraction. The events highlight the ways in which Ontarians conceptualized their history and historical meanings of place during a period of tremendous social, cultural, and economic change.

Palaeoenvironmental reconstruction at an oxbow lake situated at the lower Nottawasaga River, southern Ontario, Canada

The purpose of this investigation at the lower Nottawasaga River in southern Ontario, Canada, was to reconstruct the impact of base level on fluvial stability and human occupation during the Holocene in a topographically confined section, where the river cuts through the Edenvale Moraine. Three cores were extracted from an oxbow lake (Doran Lake) and a ground-penetrating radar survey was executed in its vicinity to study wider subsurface alluvial architecture. Radiocarbon dating suggests that the Nottawasaga River became entrenched in the Edenvale Moraine early in the Holocene, with base-level lowering in the Lake Huron basin, and that Doran Lake formed towards the middle Holocene as a meander cutoff when water levels in the Lake Huron basin increased, leading to a period of fluvial instability, enhanced flow and floodplain aggradation. Fluctuating lake levels would have affected human settlement as well as the preservation and visibility of archaeological remains predominantly through vertical accretion.

Through Water, Ice and Fire: Schooner Nancy of the War of 1812 (review)

Reviewed by: Through Water, Ice and Fire: Schooner Nancy of the War of 1812 Carl Benn Through Water, Ice and Fire: Schooner Nancy of the War of 1812. Barry Gough. Toronto: Dundurn, 2006. Pp. 213, illus., b&w, $24.99 One of the thrilling stories of the War of 1812 revolves around the adventures of the Nancy, a small commercial schooner built at Detroit in 1789 to serve on Lake Erie and the upper Great Lakes, and entered British service at the outbreak of hostilities in 1812. When the Royal Navy lost its squadron in the battle of Lake Erie in September 1813, the Nancy was away on Lake Huron, and consequently survived as Britain's largest vessel west of Niagara. With Lake Erie in American hands, she helped maintain the alternative supply lines to the upper [End Page 335] lakes, which ran northwest along fur trade routes from Montreal and north from York to Georgian Bay, then across Lake Huron to Mackinac (which the Americans had surrendered in 1812). From there, the British sent aid to the Native peoples of the upper Mississippi, who exercised dominance over the Americans in the war's far western theatre. When US forces tried to cut this lifeline in 1814 but failed to oust the British from Mackinac, they naturally targeted the Nancy, which they found hidden along the Nottawasaga River on Georgian Bay. On 14 August 1814, seventy-five sailors, soldiers, warriors, and fur traders fought 380 Americans for seven hours. However, as the situation became hopeless, the Nancy's captain, Lieutenant Miller Worsley, RN, burned his schooner and ordered a retreat. Then, early in September, under cover of darkness, Worsley and his spirited followers rowed four small boats up to one of the US Navy's vessels on Lake Huron and captured her in a short, sharp fight. Next, they used their prize to seize the other USN schooner on the lake, thereby reasserting British superiority in the northern region for the final months of the war. Meanwhile, the wreck of the Nancy disappeared under the silt of the Nottawasaga River until her remains were discovered in the early twentieth century, in part through the efforts of the well-known marine enthusiast C.H.J. Snider. They now survive as part of the Nancy Island Historic Site at Wasaga Beach, while at Toronto's Fort York a large model of the schooner commissioned by Snider captures the imagination of visitors today, particularly because it was built with wood and metal from the original Nancy. The saga of the schooner retains some currency in Ontario; thus armchair historians wishing to relive a familiar tale or explore the story for the first time might pick up Through Water, Ice and Fire, a popular retelling of the Nancy's adventure by naval scholar Barry Gough. However, they likely will be disappointed. The prose is inelegant and the research seems to be incomplete. For instance, readers might wonder why the author did not present more details about the Nancy's design, or delve more deeply into the schooner's history (such as any role she may have played in the forgotten frontier war of the 1790s). Readers also will find parts of the text confusing because there is not enough context where needed to tell the main story effectively, while in other sections, where the Nancy disappears over the horizon, the author supplies more detail about the larger conflict than is necessary for this particular book. Furthermore, the overall production values are low, as exemplified by poorly reproduced illustrations that often are nothing more than modern artists' conceptions when available [End Page 336] period views of greater documentary value would have been better. (If modern images were to be used, it would have been preferable to limit them to diagrammatic presentations, such as plans of the Nancy, or to maps that would have communicated this geographically driven story with clarity, but neither kind of illustration graces the book.) Barry Gough's Through Water, Ice and Fire seems as if it went to press before it was ready, presumably as a spinoff from his more complete Fighting Sail on Lake Huron and Georgian Bay (Annapolis: Naval...

Sewage Treatment Challenges and Opportunities in the Nottawasaga River Watershed

Abstract Sewage treatment studies at the watershed scale, compared to case-by-case community projects, ensures the most cost-efficient investment of funds commensurate with environmental requirements to sustain growth. A three-year environmental assessment study for the town of New Tecumseth, Ontario, examined all nutrient inputs to the Nottawasaga River watershed. Other challenging watershed constraints were investigated, such as stream and river flow takings for irrigation and sediment transport, prior to the selection of the master sewage treatment plan. The findings from the field research and computer modelling were used to (1) place a realistic perspective on nutrient impacts, present and future, attributable to treated sewage effluent; (2) design a master plan that could be used as an opportunity in terms of reusing the effluent locally for agricultural irrigation; (3) provide a real-time assurance of the plan’s performance/compliance, based on the actual carrying capacity of the aquatic ecosystem; (4) stage the construction of the plan in a cost-effective and environmentally sound manner; and (5) recommend a water resources management strategy to control other nutrient and sediment load sources within the watershed. The recommended master sewage treatment plan and water resources management strategy can restore the Ministry of Environment and Energy provincial water quality objective concentration for total phosphorus within the river during 7Q20 flow conditions.

Test of selected bed-material load transport models: Nottawasaga River, Ontario

Predictions from 13 bed-material load sediment transport models are compared with 19 measurements of bed-material transport in Nottawasaga River, Ontario, using summary plots and geometric statistics. Model selection is based on recent engineering application and suitability for the flow and sediment conditions of the river. The models of Laursen (1958) and Yang (1979) perform best, followed by those of Ackers and White (1973). The models of Van Rijn (1984), Maddock (1976), Karim and Kennedy (1983), Brownlie (1981), and Yang (1973) have considerable data scatter. The models of Engelund and Hansen (1967) and Shen and Hung (1972) are the poorest predictors. Poor model performance is primarily due to overestimation of flow strength needed for particle entrainment and an excessively steep slope in the relations between flow strength and sediment transport. Key words: bed-material load transport models, test, Nottawasaga River.

Multiquadric interpolation of fluid speeds in a natural river channel

An electromagnetic current meter was used to obtain fluid speeds in a meander of the Nottawasaga River, Ontario. The meter was placed at 3 m increments of width and at 0.10–0.45 m increments of depth in 13 cross-sections of the meander. Hardy's multiquadric method of interpolation, using a cone model, was implemented to estimate and map speeds more fully for each cross-section. The multiquadric system of equations was evaluated for a range of about 7–11 ( × 10 3) locations in each of nine shallow cross-sections in the upstream limb of the meander and for about 22–63( × 10 3) locations in each of four deeper sections in the downstream limb. These evaluated speeds were grouped into colour-coded classes and plotted to show the distribution of speeds in each cross-section. In all but two sections, there was one concentration of higher speeds which shifted towards the outer bank of the meander. The other two sections had double concentrations of high speeds. One section had a cluster at the surface, midstream and another at the bed, close to the outer bank. In the second section, one cluster was at the surface close to the outer bank and the other was near the bed midstream, confirming the action of helical flow in the meander. The mapping showed horizontal gradients of speed just as clearly as vertical and oblique gradients, especially where the talweg was close to the outer bank.

STREAM NITRATE‐N LOADS IN RELATION TO VARIATIONS IN ANNUAL AND SEASONAL RUNOFF REGIMES1

ABSTRACT: The calculation of stream nutrient loads from a sampling period of one year or, at most, a few years may provide an inaccurate estimate of average seasonal or annual loads due to considerable year‐to‐year variations in hydrological regime. The number of years of record required to give a reliable estimate of long‐term average NO3‐N loads was analyzed for E. Duffin Creek and the Nottawasaga River in Ontario, Canada. Nitrate load rating relationships were used in combination with a continuous stream discharge record for 22 years (E. Duffin Creek) and 34 years (Nottawasaga River) to simulate long‐term seasonal and annual variation in NO3.N loads. The errors involved in calculating average loads were examined by comparing the loads derived from sampling periods of one or more consecutive years duration with the estimated long‐term average load for the two rivers. Annual NO3‐N loads for a single year deviated from the long‐term average load by ± 20 to 53 percent in 8 out of 22 years in E. Duffin Creek and in 13 of 34 years in the Nottawasaga River. Six consecutive years of record would be required for both rivers to ensure that an error of &gt; ± 20 percent would occur in only 5 percent of these observation periods. February‐April NO3‐N loads for a single year could deviate by up to +90 percent or ‐61 percent from the long‐term average spring period load for the two rivers. A sampling period of at least 6–7 years would be needed to estimate average NO3‐N loads for the spring runoff season with an error &lt;± 20 percent.

Origin and magnetic fabric of glacial varves, Nottawasaga River, Ontario, Canada

An examination of the glacial varved clays that crop out in the banks of the Nottawasaga River, Ontario, shows that both the silt and clay layers are composed of sublaminae.An analysis of the magnetic fabric and remanent magnetization of the varves shows that the current directions are the same for the clay and silt layers and that the magnetic fabric in the clay layer was not influenced by the Earth's magnetic field. This indicates that bottom currents were active during the winter period and were of sufficient strength to align the particles of magnetite parallel to the current directions. This conclusion is not unique to the Nottawasaga varves but serves to illustrate that the conceptual model of glacial varve deposition requires modification.

Denitrification: its importance in a river draining an intensively cropped watershed

Nitrogen transport was studied during summer low flows in a 20-km reach of the Nottawasaga River which drains an intensively cropped sand plain which has an underlying shallow water-table aquifer. Nitrogen inputs to the river were measured on days in May to October of 1977-81. These data indicated that about 38% of the daily nitrate input entered the river through ground water. The magnitude of this input is a consequence of widespread contamination of the shallow aquifer by nitrogen fertilizer. Ground water entering the river from springs and seeps near fertilized fields frequently contained more than 10 mg 1 −1 of NO 3-N. Mass balance studies of nitrogen transport in the river revealed an average daily nitraof 46 ± 23 kg N. This rate of nitrate removal represented about 40% of the ground water input to the river from the sand plain. Analysis of a mass balance for total Kjeldahl nitrogen revealed an essentially balanced budget, whereas chloride showed a small daily gain of about 5%. Laboratory experiments involving the incubation of stream sediment cores and the use of the acetylene block technique suggested that the bulk of the nitrate loss during river transport was caused by denitrification in bottom sediments.

Phosphorus and major cation mass balances for two rivers during low summer flows

SUMMARY. Soluble reactive phosphorus (SRP) mass balances showed that phosphorus retention occurred during low summer flows in reaches of Duffin Creek and the Nottawasaga River, two phosphorus‐rich streams in southern Ontario. The average daily removal in Duffin Creek was 6.1 ± 1.6 kg SRP which represents the retention of about 92% of the phosphorus input. Approximately 5.3 ± 3.5 kg SRP (about 44% of the daily input) was removed from stream water in the Nottawasaga River. Laboratory experiments indicate that sorption by stream‐bed sediments is an important mechanism for phosphorus retention in both rivers. Uptake by benthic algae may also act as a temporary phosphorus sink in Duffin Creek. Major cation inputs and outputs are generally in balance, implying that these elements act in a relatively conservative manner in both rivers.

Wave Climate and Potential Longshore Sediment Transport Patterns, Nottawasaga Bay, Ontario

A storm wave climate for Nottawasaga Bay, Ontario, is hindcast, using the SMB technique, from wind records at Cove Island for the period 1966-1970. Thirteen wave classes, defined on the basis of significant wave height, period, and direction, are identified and these are used as inputs into a computer model of wave refraction within the bay. The total and longshore component of wave energy flux are determined for each wave class. The total annual energy flux P 1 and the net longshore component P 1 are determined for 55 points spaced at one kilometre intervals by multiplying the value of energy flux at each point by the mean annual frequency for that wave class and summing the values for all relevant waves. A simple model of potential erosion, transport, and deposition patterns within the bay is then developed from the variation in the net P 1 values. The predicted model is compared with geomorphological evidence of sediment transport patterns visible in vertical aerial photographs and with measurements of erosion and accretion at selected points. It is concluded that the continued eastward growth of the Wasaga spit results primarily from deposition of sediments from the Nottawasaga River rather than littoral transport.