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Hubley Big Lake, Hubley

Soil & Water Conservation Society of Metro Halifax (SWCSMH)

Updated: August 13, 2015     Woodens River watershed



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 flow chart of the Woodens River watershed;
peruse our predictive modelling, and view a relevant model; the Nova Scotia lake hypolimnion project; the paleolimnology of lakes in the HRM

The Three Brooks Development

Water Quality Report by Chambers and Scott (ca. 2001)

Chambers and Scott made significant errors in claiming that my (Mandaville) predictive model yielded a value of only 4.9 g/l (circled below in the excerpts). My model never yielded such a low value. Obviously neither Chambers nor Scott understood my somewhat intensive model.

My model actually yielded a value of 8.7 g/l based on the ca. land use stats from 1988. I, Shalom M. Mandaville, did not have any latter land use stats. The modelled value based on 2001 land use stats may indeed be higher since there was not much development in the subwatershed of Hubley Big Lake in 1988. I now understand there are hundreds of new lots served by onsite systems in the local watersheds.

It is well known that new systems served by contour beds developed by engineering scientist, David Pask PEng (as an MEng project conducted under the supervision of Prof. Dr. Dan Thirumurthy PhD PEng of TUNS), most probably, may not be contributing phosphorus via groundwater plumes for a few decades.

My models, in MS Excel format, have "Cautionary Notes" to the effect that the predictions may not represent values in coloured lakes. Hubley Big as well as most lakes within the Woodens River watershed are highly coloured per data to date. Obviously the authors of the said report did not understand what it meant; further they did not have the professional courtesy of calling me for clarification before they published their findings in the report, relevant excerpts of which have been inserted below. Further, they may have misled the public at a meeting called by the Woodens River group, which was the group that supplied me with the Chambers and Scott report.

Indeed, my models also have macros built into them which are capable of modifying the predicted values through judicious application of programmed internal regression relationships; I have carried out preliminary verification and established that my model accurately predicts the TP/Ch-a values when compared with the latest field data (of 2001).

Important Note: Predictive modelling of TP/Ch-a is more than over-simplified equations; judicious analysis is necessary as well as usage of numerous regression relationships developed not just in Ontario but also by the 18-country peer-consensus OECD studies, by the massive USEPA and the USDA, and others published in peer reviewed handbooks. In other words, to carry out predictive modelling, one needs a strong background in applied limnology. In addition, incorporation of DOC values may also be necessary in line with what I found in some urban watersheds; there are indeed select published papers in peer reviewed journals on the effect of global warming and increased UV penetration on DOC (and forms of DOC) in our sensitive pre-development primarily ultra-oligotrophic lakes.

Excerpts from the Water Quality Report of Chambers and Scott (ca. 2001):



Google Earth for the maps

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