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Selection of Phosphorus Loading Model for Nova Scotia- Phase I

February 18, 2008      

Acknowledgements

Contents:

• Cautionary notes
• Excerpts from the report

Cautionary notes

We have also established that the Ontario models (Dillon et al) are not, with exceptions, suitable for TP concentrations over 20 µg/l; for higher trophic ranges, the OECD regressions along with those derived from the OECD research are more applicable. This is probably because the OECD lakes cover a wide trophic range, from ultraoligotrophy to hypereutrophy!

In addition, Mandaville has been incorporating other regressions published in the latest international limnological journals as deemed necessary (limneschebucto.ns.ca).

As opportunity presents itself, we are continuing our intensive field sampling, generally at storm sewer outfalls (inclusive of open channels), in order to expand the data base for post-development scenarios and revise the predictive models, if needed!

With respect to areas served by septic systems, our revised models did not incorporate the same assumptions as in Hart et al (1978) and Scott et al (2003) where the authors assumed 50% septic-derived phosphorus retention in Halifax/Wolfville soils. In the Scott et al (2003) report where Mandaville was a co-author, there was an inadvertent omission made by not noting this down (and Mandaville regrets that). Our export coefficients in such areas include all potential sources of phosphorus inputs incorporated into the 50% export assumption; it actually varied from 50% in some watersheds based on local info.

Excerpts from the report

Acknowledgements

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