Lit & Links

• Municipal Watershed Management Framework
  Item No.13.1.2 Environment and Sustainability Standing Committee August 1, 2024. Includes the document: Framework for Integrated Watershed Management in the Halifax Regional Municipality, dated June 13, 2024

• Municipality launches LakeWatchers Water Quality Monitoring Program
  HRM News Release Apr 20, 2022. View Website

• Water Quality Monitoring Policy & Program Development
  HRM Environment & Sustainability Standing Committee June 3, 2021. “It is recommended that the Environment and Sustainability Standing Committee recommend that Halifax Regional Council direct the Chief Administrative Officer to: 1. Adopt and implement a detailed water quality monitoring program based on Framework 1 as outlined by AECOM in their Water Quality Monitoring Policy and Program Development Report, as outlined in the Discussion section of this report.” Note: Sandy Lake is one of the Class A, High Vulnerability Lakes which will have 2 sampling events per year at each lake – once in spring during mixed-water column conditions &  once at the end of summer.

• Halifax Regional Municipality Water Quality Monitoring Policy and Program Development
  Prepared by: AECOM Canada Ltd., Sep 2020 99 pages + Appendices. Some context. Sandy Lake is cited as a “Priority Lake” for monitoring, with 2 of 3 water quality issues – Eutrophication and Bacteria –  by the following criteria:

  Priority Eutrophication Lakes – lakes with elevated surface water TP concentrations during the ice-free period that are indicative of eutrophic conditions (i.e., >20 μg/L) based on a high-level review of monitoring data from select sources, and lakes with documented past issues with algal blooms or nuisance aquatic plant growth.

  Priority Chloride Enrichment Lakes — lakes with elevated spring surface water chloride concentrations (i.e., >100 mg/L) that are approaching the Canadian Water Quality Guideline (CWQG) of 120 mg/L for long-term exposure for freshwater aquatic life, based on a high-level review of monitoring data from select sources.

  Priority Bacteria Contamination — lakes with municipal beaches where HRM provides
  supervision due to human health risks from recreational body contact with water.

Assessing and predicting Lake Chloride Concentrations in the Lake-Rich Urbanizing Halifax Region, Canada
Tessa Bermarija et al., 2023. in Journal of Hydrology: Regional Studies Volume 47, June 2023, 101377. “Highlights
• [Cl-] was correlated with urban cover, road density, and stormwater pipe density.
• Annual Cl- loading rates were developed for urban land uses.
• A mass balance model was developed to predict Cl- loading to lake
New hydrological insights for the region
-The watershed variables found to be most predictive of mean lake [Cl-] were the % urban coverage, road density, and stormwater pipe density in a watershed.
-Annual Cl- loading rates for the four primary land use categories in the region were: rural 1–3 g/m2/yr, commercial 0–9 g/m2/yr, residential 97–162 g/m2/yr, and roads 804–964 g/m2/yr…
From the Introduction: The Halifax Regional Municipality (HRM) in the Canadian province of Nova Scotia has been rapidly urbanizing over the past 40 years, with associated impacts to lake water quality (Doucet, 2022). Of particular note, the combination of dense road networks and high frequency of winter weather events leads to heavy use of de-icing salts to ensure winter road safety (Environment Canada & Health Canada, 2001). Spring peaks and fall minima of lake [Cl] are typical in the HRM as most lakes have flushing rates that exceed 1/yr and watersheds have little capacity for storage in groundwater/soils, thus all road salts are thought to reach receiving waters within one year of their application (Scott et al., 2019). Synoptic decadal surveys of HRM lakes dating back to 1980 have measured elevated and increasing [Cl-] (Clement and Gordon, 2019). Though the Road Salt Code of Practice has been in place for nearly 20 years, many HRM lakes still experience spring exceedances of the chronic guideline level, and some of these lakes have experienced significant increases in spring [Cl-] since 2011 (Doucet, 2022). This pattern suggests that the recommended mitigation methods, or the levels of uptake, are not adequate to protect aquatic habitats.”

Synoptic snapshots: monitoring lake water quality over 4 decades in an urbanizing region
C. Doucet et al., 2023. In Lake Reservoir Management. “Synoptic water quality surveys—measuring major ions, nutrients, pH, organic matter, and trace elements—have been conducted in ∼50 lakes in the Halifax Regional Municipality (Nova Scotia, Canada) once per decade since 1980. In this study, lake water quality over 40 yr was examined and urban development was evaluated as a possible driver of observed changes. More than half of the lakes experienced strong (>50%) increases in conductivity, iron, sodium, chloride, calcium, and total phosphorus (TP), and strong decreases in acidity (i.e., [H+]). Between 20% and 50% of the lakes experienced strong increases in nitrate, alkalinity, zinc, color, aluminum, dissolved organic carbon, and magnesium, and strong decreases in manganese and sulfate. In 2021, national guidelines for the protection of aquatic life were exceeded by chloride, aluminum, manganese, and arsenic in certain lakes. Land cover classification from circa 1980 and 2020 revealed that although change in urban development within the lake watersheds ranged from a decrease of 11 percentage points to an increase of 48 percentage points, the majority (90%) of watersheds experienced an increase. Urban development was associated with increased chloride, conductivity, sodium, calcium, and TP concentrations. Other parameters appear to be more influenced by hydrology, watershed characteristics, climate, and decreased acid deposition. Results highlight emerging water quality concerns, such as elevated aluminum concentrations, and increased concentrations of chloride, nutrients, and arsenic, which should be the focus of strategic monitoring and mitigation efforts.”

The Doucet et al., 2023 paperreports on the the 5th “synoptic” survey of 51 Halifax area lakes, all conducted over 1-2 days soon after ice-out, that by Doucet et al. 2023 was in 2021.
Others:

Gordon DC, Keizer PD, Ogden JG, IIIUnderwood J, Wiltshire JF. 1981. Synoptic water quality study of fifty lakes in the Halifax, N.S. metro area on 14 April, 1980. Bedford Institute of Oceanography.

Keizer PD, Gordon DC, Rowell TW, McCurdy R, Borgal D, Clair TA, Taylor D, Ogden JG, III, Hall GEM. 1993. Synoptic water quality survey of Halifax/Dartmouth metro area lakes on April 16, 1991. Available from https://publications.gc.ca/site/eng/449551/publication.html.

Clement PM, Keizer PD, Gordon DC, Clair TA, Hall GEM. 2007. Synoptic water quality survey of selected Halifax Regional Municipality lakes on 28–29 March 2000. Available from https://novascotia.ca/nse/surface.water/docs/SynopticWaterQualitySurvey-MetroHalifaxLakes-2000.pdf.

Clement PM, Gordon DC. 2019. Synoptic water quality study of selected Halifax-area lakes: 2011 results and comparison with previous surveys. Available from http://epe.lac-bac.gc.ca/100/201/301/weekly_acquisitions_list-ef/2019/19-17/publications.gc.ca/collections/collection_2019/mpo-dfo/Fs97-4-3170-eng.pdf.

Identifying lake water quality trends and effective monitoring strategies in a rapidly urbanizing region
Doucet, C., 2022, [Master of Applied Science, Dalhousie University]. http://hdl.handle.net/10222/82119. The thesis gas two Results Chapters. Chapter 2,  Chapter 3: Tracking trophic state in urban lakes in a changing climate: are existing monitoring protocols still effective?

Sandy Lake Watershed Study Final Report
AECOM, 2014. 131 pages. History, maps etc.  Also view Lakeshore Capacity Modeling Results, Revised Planned Development extended . Also view Halifax Regional Municipality Watershed Studies Preston Area and Sandy Lake AECOm Slide Presentation by Russel Dmytriw at the Regional Watershed Advisory Board
March 12, 2014.

Sandy Lake Watershed Study – Additional Modeling Scenario
A letter dated Feb 12, 2015 addressed to Mr. Cameron Deacoff, Planning and Infrastructure Halifax Regional Municipality from Steve Murphy, MBA, P.Eng. Senior Manager, AECOM/Atlantic Canada. It has not been published on the HRM website or otherwise made available but was listed amongst info documents given to consultants reviewing the ‘Optimal boundaries for Sandy Lake Regional Park (see Post, Nov 10, 2021). The consultants made a preliminary report to HRM 7 stakeholders on mar 29, 2022, at which time the document was made available. Amongst the results: “The results of the Lakeshore Capacity Modeling for the Scenario 2b suggests the phosphorus concentrations in both Sandy Lake and Marsh will exceed the Water Quality Objectives set in the
Sandy Lake Watershed Study Final Report (AECOM 2014).

Halifax Regional Municipality Water Quality Monitoring Policy and Program Development
Prepared by: AECOM Canada Ltd., Sep 2020 99 pages + Appendices. Some context. Sandy Lake is cited as a “Priority Lake” for monitoring, with 2 of 3 water quality issues – Eutrophication and Bacteria –  by the following criteria:

Priority Eutrophication Lakes – lakes with elevated surface water TP concentrations during the ice-free period that are indicative of eutrophic conditions (i.e., >20 μg/L) based on a high-level review of monitoring data from select sources, and lakes with documented past issues with algal blooms or nuisance aquatic plant growth.

Priority Chloride Enrichment Lakes — lakes with elevated spring surface water chloride concentrations (i.e., >100 mg/L) that are approaching the Canadian Water Quality Guideline (CWQG) of 120 mg/L for long-term exposure for freshwater aquatic life, based on a high-level review of monitoring data from select sources.

Priority Bacteria Contamination — lakes with municipal beaches where HRM provides
supervision due to human health risks from recreational body contact with water.

The effects of land use changes on water quality of urban lakes in the Halifax-Dartmouth region: Sandy Lake
Pages from Paul Mandel, MSc thesis, Dalhousie University, 1994. Observations on Sandy Lake on 4 dates 1991/1992, and comparison with 1971 data.

Sandy Lake Development Impact Assessment Final Report – A Water Quality Analysis
Damon Conrad, Hany Sidhom, Steve Matthews, W. Hart 2002
“This report, created by senior Environmental Engineering students from Dalhousie University in 2001-02, involves the examination of Sandy Lake and surrounding area, in Bedford, Nova Scotia. Due to developmental pressures in the area from the major metropolitan area of Halifax Regional Municipality (HRM), Sandy Lake is of concern
regarding its relatively undeveloped shoreline. The initiating factor of this report is a beach and park project to be developed by HRM, which started construction in 2001 and will be completed over the following few years. This report involves the creation of baseline data including dissolved oxygen, pH, total suspended solids, a bathymetric map of the lake, total and fecal coliform, as well as other water quality parameters…. This report was intended to be retained for the purpose of maintaining a historic record of Sandy Lake and its surrounding area as well as to outline environmentally responsible practices regarding any future development.”

Water Quality Monitoring in the Sackville River Watershed 2015 and 2016
Bill Ernst and Damon Conrad, Sackville Rivers Association November 2016.

Establishing realistic management objectives for urban lakes using paleolimnological techniques: an example from Halifax Region (Nova Scotia, Canada)
Brian K. Ginn et al., 2015 Lake and Reservoir Management, 31:2, 92-108 “To determine pre-disturbance limnological conditions, evaluate the impact of environmental stressors (surface water acidification, nutrient inputs, climate change, and winter deicing salt), and set realistic recovery targets for lake management strategies, a rapid assessment paleolimnological approach was used to determine the amount (and likely causes) of environmental changes over the past ∼100–150 years in 51 urban lakes from Halifax, Nova Scotia (Canada). Diatom assemblages from lake sediment cores were used with “top” (recently deposited, surface) samples being matched to measured limnological conditions, and “bottom” (generally from >15 cm deep) samples used to infer pre-disturbance limnological conditions such as pH, total phosphorus (TP), specific conductance, and shifts due to changing climatic conditions. Environmental change was assessed by calculating the metric of change in species composition between present-day and pre-disturbance diatom assemblages, and inferences from quantitative estimates of diatom-inferred pH, specific conductance, and TP. All 51 study lakes have experienced floristic changes in diatom species composition since pre-disturbance times, but different environmental stressors were implicated: 8 of the 51 lakes underwent significant (i.e., >2 times the root mean-squared error [2X RMSE] of the inference model) decreases in diatom-inferred pH; 8 lakes had significant increases in diatom-inferred TP; and 19 otherwise relatively pristine lakes had increases in planktonic taxa consistent with observations linked to changes in lake seasonality and limnological changes most closely linked to climate warming in Nova Scotia and other regions. The remaining 16 lakes did not have large and consistent changes in diatom flora or changes in diatom-inferred TP or pH >2X RMSE of the prediction of the models. Lake-specific factors were related to these inferences, and the lakes that acidified were mainly the currently most acidic sites, whereas those that experienced issues related to eutrophication were generally among the most alkaline sites. Of our 51 lakes, 22 (including some experiencing pH, TP, or showing floristic changes linked to climate changes) had increases in measured conductivity (1980–2002) and, correspondingly, increased relative abundances of halophilic diatom taxa. These lakes, often with catchments containing high surface areas of impervious surfaces, are examples of a trend of increasing salinity in northeastern North American lakes likely related to winter application of deicing (road) salt. The application of this paleolimnological approach enabled us to identify which lakes have undergone significant changes in diatom assemblages, as well as which environmental stressor(s) were most probable. This information can help lake managers develop more targeted and effective management strategies.” Sandy Lake was one of the “19 otherwise relatively pristine lakes had increases in planktonic taxa consistent with observations linked to changes in lake seasonality and limnological changes most closely linked to climate warming in Nova Scotia and other regions.” Sampling: “Sediment cores were collected from 51 lakes in Halifax Region in July 2005 and July 2006”

SACKVILLE RIVER WATERSHED WETLAND INVENTORY PT. 2: BIG SANDY LAKE SUB-WATERSHED
John-William Brunner/Sackville Rivers Association. 2011. Prepared for the Nova Scotia Department of Transportation and Infrastructure Renewal (NSTIR-ESS File: 17.008.09) Describes 7 sites. Farmer’s Dairy Site on Goggle Earth here
Full Report: Sackville River Watershed Wetland Inventory
:Wet Area Mapping (WAM) data was acquired and assessed in the field to identify and inventory wetland and wet area sites to locate areas for wetland creation, enlargement, and enhancement. These sites could be used for potential future wetland compensation projects in the Sackville River Watershed (SRW). The inventory project was initiated as part of the compensation for damaged wetlands from new interchanges on Highway 101 and 102 and the new French high school in the Halifax Regional Municipality. The WAM data was found to be accurate in identifying wet areas in the surveyed portions of the SRW. Three of the SRW’s most urbanized sub-watersheds were field inventoried and revealed non-wetland wet areas as well as new, potential, and existing wetlands. These areas yielded the possibility for a total of 142,743 square meters of wetland creation, restoration, and enhancement. The remaining 10 sub-watersheds require 6 months of GIS work, field work, and report writing which could reveal approximately 100 additional wetland creation, enlargement, and enhancement sites.”

Peverill’s Brook – An Atlantic Salmon Conservation Foundation and Adopt-a-Stream Sponsored Project
“At Peverill’s Brook this summer, we measured the area that needed and could be worked on to determine the amount of digger logs we could install. Among all of our other work, this summers crew (2012) managed to install eleven logs along Peverill’s and enhanced one natural rock sill. We divided the stream into a lower and upper section, between which lies marsh lake. These before and after pictures clearly illustrate the narrowing of the channel widths, and when the water is high, how much oxygen gets plunged into the river as pools get dug out for the fish.”

Invertebrate Predation and the Seasonal Dynamics of Microcrustacea in the Littoral Zone of Jack Lake, Nova Scotia
Michael J. Paterson PhD thesis, Dalhousie University

Characterizing Sources of Fecal Pollution at Four Urban Public Beaches in the Halifax Regional Municipality
Michael McDonald, 2016. MSc thesis “Within the last few years several beaches in the Halifax Regional Municipality have closed frequently due to increased levels of E. coli within the beach waters. Enumeration, microbial enrichment, and genetic microbial source tracking methods were used to enumerate E. coli levels and detect the presence of select pathogens and host-specific fecal contamination markers within four local freshwater urban beaches. E. coli levels mostly remained below the maximum allowed concentration throughout the sampling season. Tested pathogen and fecal contamination markers displayed a low prevalence. E. coli levels were influenced by measured water quality parameters and were shown to fluctuate on a day-to-day basis. However, E. coli were unable to predict the presence of enteric pathogens or fecal contamination markers. The beaches do not appear to be heavily contaminated and should generally be safe for public use. The use of E. coli as a fecal indicator needs to be further assessed in future studies.” Sandy lake was one of the study lakes, “chosen as a control beach due to a history of good water quality and location in a relatively unpopulated area”. He looked specifically for dog contamination, concluding Overall, the low prevalence of the BacCan marker indicates that dogs may not be a large source of contamination at the tested beaches and the ban on dog’s access to beaches imposed by the HRM is being obeyed.”

Sackville Rivers Association (SRA) (website)
The Sandy Lake watershed is a subwatershed of the Sackville River watershed. The SRA is a highly active organization which works to
1) Protect and where necessary restore the environment of the Sackville River Watershed
2) Raise awareness about the environment of the Sackville River watershed and its adjacent watersheds
3) Establish a Conservation Corridor along the length of the Sackville River
4) Provide training and advice to community groups in other watersheds as needed, to restore the environment and raise environmental awareness

SANDY LAKE, Bedford:- Accelerated eutrophication signs, and suggested restoration parameters
S. M. Mandaville to Chair & Members, North West Community Council, HRM, October 30, 2013 “I include the predictive phosphorus modelling conducted by my team some years back
(results updated in page-5, and the pictorial model in page-7). The enrichment has already occurred (see page-3 on suggested action by the NWCC)…The goal of restoration should be a maximum deep station TP of 9 μg/l”. Also view Excel file for Sandy Lake

View Series Index and article on Why Urban Lakes are Different

Managing Phosphorus Inputs Into Lakes
Originally published in  Davenport, Tom; Kaynor, Susan.  Watershed Protection Techniques, suppl. SPECIAL ISSUE: Urban Lake Management; Ellicott City Vol. 3, Iss. 4,  (Dec 2001) PDFs avilable at links below:
– Introduction
I: Determining the Trophic State of Your Lake
– II Crafting an Accurate Phosphorus Budget for your Lake
– III Evaluating the Impact of Watershed Treatment
Urban Lake Management
Related: The Influence of Septic Systems at the Watershed Level

Lakeshore Capacity Assessment Handbook: Protecting Water Quality in Inland Lakes on Ontario’s Precambrian Shield Appendix A: Rationale for a Revised Phosphorus Criterion for Precambian Shield Lakes in Ontario
Ontario Ministry of Environment May 2010. Comprehensive. “The relationship between phosphorus and oxygen is implicit in any lake management activities and should, at least, be considered in formulating the PWQO [Provincial Water Quality Objective].

Lake Tropic Status
RMB Environmental Laboratories. Basic Into. Other topics related to the physical, chemical and biological components of lakes are covered in their Lake Primer

Defining Trophic State
North American Lake Management Society. A more in-depth explanation.

A trophic state index for lakes
RE Carlson 1977 LImnology and Oceanography “A numerical trophic state index for lakes has been developed that incorporates most lakes in a scale of 0 to 100. Each major division (10, 20, 30, etc.) represents a doubling in algal biomass. The index number can be calculated from any of several parameters, including Secchi disk transparency, chlorophyll, and total phosphorus.”

Trophic response to phosphorus in acidic and non-acidic lakes in Nova Scotia, Canada
J Kerekes et al., 1990 Hydrobiologia 191, pages105–110 “Twenty lakes (oligotrophic or eutrophic) with a wide range of acidity (pH 3.5 to 7.6) show a typical trophic response to total phosphorus with respect to algal biomass (OECD relationship), irrespective of their acidity. Zooplankton abundance is also related to total phosphorus, except for an outlier lake which is very acidic and eutrophic. This lake, however, has an abundant benthic and pelagic insect fauna and shows an overall ‘normal’ trophic response to phosphorus. In three lakes where planktonic primary production at light optimum (P maxwas measured, it was highest in the most acid lake (pH 4.4) which has the largest total phosphorus concentration.”

User’s Manual for Prediction of Phosphorus Concentration In Nova Scotia Lakes: A Tool for Decision Making Version 1.0
M. Brylinsky, 2004. Prepared For The Nova Scotia Water Quality Objectives and Model Development Steering Committee Nova Scotia Department of Environment and Labour. 88 pages. As well as describing the use of this commonly used model, the document provides a basic introduction to phosphorus in aquatic systems cycling and the rationale for focussing on phosphorus to predict lake trophic status.

Sandy Lake Watershed Study Final Report
AECOM, 2014. 131 pages. Comprehensive review of what’s known about Sandy Lake and Marsh lakes and area, and desktop modelling of impacts of development on phosph0rus levels. View also the Response of Sandy Lake Conservation Association (SLCA) to this report.

Pollution Source Control Study for Lake Banook & Lake Micmac Final Report
Stantec Consulting Ltd. for Halifax Regional Municipality, 2019. The same P model was used as in the AECOM report but with a lot of field observations included.

Non-floodplain Wetlands Affect Watershed Nutrient Dynamics: A Critical Review
Heather E. Golden et al., 2019.Environmental Science & Technology 53 (13), 7203-7214 “Wetlands have the capacity to retain nitrogen and phosphorus and are thereby often considered a viable option for improving water quality at local scales. However, little is known about the cumulative influence of wetlands outside of floodplains, i.e., non-floodplain wetlands (NFWs), on surface water quality at watershed scales. Such evidence is important to meet global, national, regional, and local water quality goals effectively and comprehensively. In this critical review, we synthesize the state of the science about the watershed-scale effects of NFWs on nutrient-based (nitrogen, phosphorus) water quality. We further highlight where knowledge is limited in this research area and the challenges of garnering this information. On the basis of previous wetland literature, we develop emerging concepts that assist in advancing the science linking NFWs to watershed-scale nutrient conditions. Finally, we ask, “Where do we go from here?” We address this question using a 2-fold approach. First, we demonstrate, via example model simulations, how explicitly considering NFWs in watershed nutrient modeling changes predicted nutrient yields to receiving waters–and how this may potentially affect future water quality management decisions. Second, we outline research recommendations that will improve our scientific understanding of how NFWs affect downstream water quality.”

How effective are created or restored freshwater wetlands for nitrogen and phosphorus removal? A systematic review
Magnus Land et al., 2016.Environ Evid 5, 9 Conclusions On average, created and restored wetlands significantly reduce the transport of TN and TP in treated wastewater and urban and agricultural runoff, and may thus be effective in efforts to counteract eutrophication. However, restored wetlands on former farmland were significantly less efficient than other wetlands at TP removal. In addition, wetlands with precipitation-driven HLRs and/or hydrologic pulsing show significantly lower TP removal efficiencies compared to wetlands with controlled HLRs. Loading rate (inlet concentrations × hydraulic loading rates) needs to be carefully estimated as part of the wetland design. More research is needed on the effects of hydrologic pulsing on wetlands. There is also a lack of evidence for long-term (>20 years) performance of wetlands.

Phosphorus Retention in Streams and Wetlands: A Review,
K. R. Reddy , R. H. Kadlec , E. Flaig & P. M. Gale (1999) Critical Reviews in Environmental Science and Technology, 29:1, 83-146,

Reducing Phosphorus to Curb Lake Eutrophication is a Success
David W. Schindler et al., 2016 Environ. Sci. Technol. 2016, 50, 17, 8923–8929 “As human populations increase and land-use intensifies, toxic and unsightly nuisance blooms of algae are becoming larger and more frequent in freshwater lakes. In most cases, the blooms are predominantly blue-green algae (Cyanobacteria), which are favored by low ratios of nitrogen to phosphorus. In the past half century, aquatic scientists have devoted much effort to understanding the causes of such blooms and how they can be prevented or reduced. Here we review the evidence, finding that numerous long-term studies of lake ecosystems in Europe and North America show that controlling algal blooms and other symptoms of eutrophication depends on reducing inputs of a single nutrient: phosphorus.”

Nutrient removal effectiveness by riparian buffer zones in rural temperate watersheds: The impact of no-till crops practices
T.R.Aguiar Jr. et al., 2015 Agricultural Water Management 149: 74-80 “…buffer zones with 60 m width composed of woody soils were more effective in phosphorus (99.9%) and nitrogen (99.9%) removal when compared to shrub (66.4% and 83.9%, respectively) or grass vegetation (52.9% and 61.6%, respectively) areas. Woody vegetation has deep rooting systems and woody soils have a higher content of organic matter when compared to grass and shrubs areas.”

Small differences in riparian vegetation significantly reduce land use impacts on stream flow and water quality in small agricultural watersheds
J.W. Chase et al. 2016 Journal of Soil and Water Conservation May 2016, 71 (3) 194-205. “… In northwest New Brunswick’s potato (Solanum tuberosum L.) growing region, once densely forested riparian corridors now often contain only scattered, irregular patches of residual vegetation, and national water quality standards for streams are regularly exceeded. The objective of this study was to ascertain whether relatively small differences in riparian forest cover are of any significant benefit to stream environments…. Our results conclusively show that relatively small increases in riparian forest cover will lead to statistically detectable and ecologically meaningful improvements to stream health.”

ON ANOXIA  &  INTERNAL P LOADING

Quantifying anoxia in lakes
By G.K. Nurnberg 1995 in Limnology & Oceanography. PDF “Abstract
The anoxic factor (AF, days per year or per season) can be used to quantify anoxia in stratified lakes. AF is calculated from oxygen profiles measured in the stratified season and lake surface area (A,) asAF = (duration of anoxia x anoxic sediment area)/& AF represents the number of days that a sediment area, equal to the whole-lake surface area, is overlain by anoxic water. Average AF for 56 central Ontario lakes, 19 additional eastern North American lakes, including the Laurentian Great Lakes and several acidified lakes, ranged from 0 to 83 d per summer…Annual variation within lakes was large and partly ascribed to variable annual loading of DOC. AF was not correlated with areal hypolimnetic oxygen depletion, because of the opposing dependency on lake shape, but was correlated with Reckhow’s probability of anoxia in eutrophic lakes. AF was also correlated with the redox potential of anoxic water at the end of summer stratification, especially after inclusion of an estimate of iron concentration in the sediment.”  She classified anoxic water as water with 1 mg/L and less oxygen; under some circumstances, 2 mg/L and less.

Internal phosphorus loading in Canadian fresh waters: a critical review and data analysis
DM Orihel et al., 2017. Can. J. Fish. Aquat. Sci. 74: 2005–2029.

Discussion
This study shows that the Ontario LCM oxygen model can be used to accurately predict hypolimnetic oxygen profiles for lakes in Nova Scotia. BRYLINSKY (2002) studied 20 previously-stocked brook trout lakes, 11 classified as good and 9 classified as having poor cold- water fish habitat. A later survey of the same lakes showed that only 2 provided suitable habitat (Millet and Frenchclearwater lakes); however, the measurements in these lakes (e.g., Frenchclearwater Lake) did not include all of the hypolimnion. Our study did not con- sider Frenchclearwater Lake as suitable habitat based on predicted VWHOC. This discrepancy could be attributed to BRYLINSKY (2002) not collecting DO measurements below 10 m, while the lake is 21 m deep, with the thermocline beginning at 12 m. Other researchers have utilized a limit of DO concentrations > or = 3 mg/L for coldwater fish habitat (STEFAN et al. 1995, FANG et al. 2004). Using this limit, 3 of the study lakes have good habitat: Millet, Lumsden and Long lakes.

Hincast, pre-development TP concentration (Table l) could be used as an indicator of potential brook trout habitat and to set restoration goals. Habitat remediation should best focus on lakes showing evidence of historic coldwater fish habitat. In this study, not only did current measurements indicate poor habitat quality, but hindcast water quality did not indicate good historic coldwater fish habitat for any of the lakes (VWHOC > or = 5 mg/L). These are worrisome results, as the province re-stocks these lakes every year. In the long term, it may be more economical for managers to consider introducing self- sustaining populations in lakes where good habitat exists or to restore water quality in lakes where good habitat once existed.

Based on this study, Nova Scotia now has useful tool for predicting the VWHOC for stratified lakes. This model can be used to develop realistic remediation goals based on hindcast, pre-development TP concentrations, in hopes to better manage brook trout populations.

Predicting End-of-Summer Oxygen Profies in Stratified Lakes
LA Malot et al., 1992. Canadian Journal of Fisheries and Aquatic Sciences
Mean end-of-summer dissolved oxygen profiles in the hypolimnion of oligotrophic and oligornesstrophic thermally stratified lakes were accurately predicted with a multivariate regression model. The model integrates the effects of lake morphometry, total phosphorus concentration (TP), and initial O2 concentrations at spring turnover to predict mean end-of-summer O2 concentration within individual hypolimnetic strata. Lake morphometry exerts a large influence on O2 profiles and this influence is particularly evident in shallow (<20 m maximum depth) oligotrophic lakes. Predictions sf O2 profiles are sensitive to changes in TP concentrations, with all study lakes predicted to have severely 0,-depleted hypolimnions by the end of summer at an epilimnetic TP of only 15 ug/L .

Predicting the location of optimal habitat boundaries for lake trout (Salvelinus namaycush) in Canadian Shield lakes
PJ Dillon et al., 2003. Canadian Journal of Fisheries and Aquatic Sciences “The optimal habitat boundary for lake trout (Salvelinus namaycush Walbaum) has been defined as that portion of the lake having both more than 6 mgL–1 oxygen and temperature less than 10 °C. Here we use an existing hypolimnetic oxygen model to define the lower boundary of the optimal habitat by identifying the depth at which 6 mgL–1 oxygen occurs at the end-of-summer stratification period. Then we develop a new model to predict the 10 °C depth or upper habitat boundary for the same date. These two boundaries can be used in conjunction with measured individual strata volumes to calculate the optimal habitat volume. Parameters needed for the models include lake morphometry, total phosphorus (TP) concentration, and Secchi depth or dissolved organic carbon (DOC) concentration. Thus, the optimal habitat model can be used to predict the effects on optimal habitat volumes of changes in trophic status (increases or decreases in TP), or changes in light transmission (caused by changes in DOC or its surrogate in these lakes, i.e., Secchi depth) that result from changes in climate, land use, acid–base status, or incident ultraviolet radiation levels.”

Lake classification in Nova Scotia from phosphorous loading, transparency and hypolimnetic oxygen consumption
Schwartz, P. Y. and Underwood, J. K. Proc. Nova Scotian Institute of Science 1986. “Three indices of eutrophication are used to compare effects of urbanization on seven headwater lakes near Halifax, Nova Scotia. Annual (1983) inputs of phosphorus were calculated and compared with lake Secchi transparencies and rates of consumption of hypolimnetic oxygen (Thienemann index). Results from transparency and oxygen deficits were similar but implied greater eutrophication than did the phosphorus index. Brief discussion of some inherent problems of each index is included.