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First Lake, Lower Sackville

Soil & Water Conservation Society of Metro Halifax (SWCSMH)

Updated: October 30, 2021

 Shubenacadie River headwaters

Caution: Since First is a shallow lake, the standard limnetic (i.e., open-water) trophic parameters may not represent the true trophic status of the lake



Water Quality

Chemical vs Biological monitoring

Select scientific modelling and chemical/biological limnology are part of our miscellaneous archives

The bathymetric map; the morphological data; the location map; the Shubencadie River headwaters flow chart;
peruse our predictive modelling, and view a relevant model; the paleolimnology of lakes in the HRM

  •  Deep station total phosphorus (TP)- comparison with our hindcast models; October 18, 2013
  • Phosphorus:- Details on LCC (Lake Carrying Capacity)/Threshold values of lakes, and comparison with artificially high values chosen by the HRM; March 14, 2014

  • Img-smallmouth3.jpg

    Overview of our concerns

    Our primary concerns re this lake have been w.r.t the various symptoms associated with cultural eutrophication inclusive of severe dissolved oxygen depletion in the hypolimnium during the critical periods of summer months. As the year-2004 CCME Policy on Phosphorus (TP) clearly narrates that not adhering to the reference/background (i.e., the natural pre-development value) + 50% maximum increase concept, even if they fall within the reference/background trigger ranges, could result in significant changes to the `COMMUNITY STRUCTURE' (cf. eutro1, and eutro2)!

    Our secondary concern has been with sporadic high fecal counts in parts of the lake and no single location has been indicative of the overall fecal pollution from multiple sources.

    There has been no scientific evidence of any reduction and/or return to its natural background values based on our predictive TP modelling.

    Even of more importance as a comparison are the trophic guidelines of the CCME and the indicator thresholds for anthropogenic stressors of freshwater lakes in Nova Scotia.

    This is one of the lakes in HRM which has been studied extensively by various researchers inclusive of us limnologists as well as by paid consultants. The vast majority of the scientific and consultant studies are easily available to the public through a combination of the Novanet library system, the HRM, and our OneDrive.

    Hypolimnetic lake aeration prescribed


    There have been several successful case histories of lake aeration worldwide as well as in Canada.

    Concerns of stakeholders and Government agencies


    Google Earth for the maps

    The jpeg scan of the fish was extracted by biologist, Peter Shacklock, from the Tv show we had produced featuring underwater video of the fish species of the Shubenacadie Lake system during year-1994.

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