The Lake Huron Centre For Coastal Conservation
Advocating Wise Stewardship of Lake Huron's Coastal Ecosystems
Nutrients
In the environment, nitrate is the frequent form of inorganic nitrogen. For nitrate, 4 mg/L is the level that has been proposed by the National Guidelines and Standards Office (Environment Canada) as indicative of eutrophic conditions and tends to stimulate algal blooms. The Maitland Valley Conservation Authority typically uses this level in monitoring watershed health. This level has been used in this report as the target for nitrate levels for comparing testing results.
Phosphate is the most readily available form of phosphorous and, above a certain threshold can be harmful to aquatic systems. The interim PWQO for total phosphorous for lakes is generally 0.02 mg/L., and for rivers it is 0.03 mg/L. Algae blooms are associated with levels above 0.02 mg/L and so this is the target level used in this report for phosphorous levels and comparing testing results.
Nitrate and total phosphorous testing has occurred in specific locations along the study area. The Township of Huron-Kinloss has included these parameters in recent monitoring of the Pine River sub-watershed. In 2002, 20% of the nitrate samples taken (40 of 204) were above 4 mg/L. For total phosphorous, 76.5% of samples (130 of 170) exceeded 0.02 mg/L.. Data suggest that average nitrate concentrations in some monitoring locations relatively close to the lakeshore have been on an upward trend from 1965 to 2003 (Ross, B.M., 2004)
The Ashfield-Colborne Lakefront Association also carried out testing for nitrates and total phosphorous. In 2002, 38% of their samples (51 of 135) were over the 4 mg/L target. Total phosphorous levels were low at only 6% (6 of 104) of samples taken exceeding 0.02 mg/L.
Bonte-Gelok and Joy (1999), ranked the data for Huron County to illustrate which areas of the county had the highest concentrations, and the highest loadings, of pollutants. In general, the highest concentrations of pollutants occur in the southern portion of the county. Nitrate concentrations were highest in the Bayfield River and lakeshore gullies. The highest loadings of nitrate to Lake Huron occurred on the Maitland and the Bayfield Rivers. Total phosphorous concentrations were highest at the south end of the county, particularly in the lakeshore gullies and the Ausable River. Total phosphorous loadings were highest on the Maitland River.
No citizens group appear to have been analyzing Nitrogen or Total Phosphorous levels in Bruce County or Lambton County.
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The Lake Huron Centre for Coastal Conservation P.O. Box 178, Blyth, Ontario, Canada N0M 1H0 Phone: (519) 523-4478 Email: coastalcentre@lakehuron.on.ca |
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