Water Quality

Released in June 2018

Tay River Subwatershed Report

The Rideau Valley Conservation Authority (RVCA) prepares an extensive report on the environmental health of the Tay River Subwatershed, which includes Bobs and Crow lakes.   The 2017 report was released in July 2018 and provides high level very poor to very good assessments of water quality.  For a full copy of the report for the Tay River Subwatershed, click on the button below or go to Community News & Events/Documents:

Click to download Subwatershed Report

Bobs Lake Catchment Report

2017 Catchment report available towards end of 2018

The RVCA also prepares individual  reports for each major "Catchment Area" making up the Tay River Subwatershed.   These reports provide the detailed water testing data for Bobs and Crow lakes.   These reports provide detailed technical data on water clarity, nutrient levels, oxygen, ph, E. Coli and temperature.  The most recent reports are from 2011, however the 2017 reports are expected to be released towards the end of 2018.   For a full copy of the reports click on the button below or go to Community News & Events/Documents.

Click to download Catchment Report

How is Water Quality Measured?

Water quality ratings for Bobs and Crow lakes are comprised of several water quality parameters, when blended together are translated into 4 quality categories:  Very Poor to Poor, Fair, Good and Very Good.   These ratings are geared towards the protection of aquatic life and are not suitable for assessing water quality for recreational activities at the cottage.

The water quality parameters used to calculate the rating are:  phosphorus(nutrients), Kjeldahl nitrogen(nutrients), dissolved oxygen/temperature conditions(fish habitat), pH(degree of acidity/alkalinity) and Secchi depth(water clarity).     There are 12 monitoring sites for Bobs and Crow lakes. 

2017 Tay River Subwatershed Report Findings:

The report indicates that all of the test sites in Bobs and Crow lakes, have water quality levels of Fair to Good except Mill Bay, which is Fair to Poor.  However since the previous report in 2011, Mill Bay has shown an incremental improvement from Very Poor to Poor.  This improvement is attributed to less frequent exceedances in the nutrient parameters.

 Mill Bay and Mud Bay are shallow areas of Bobs lake.  Due to the approximately 1 meter drop in the lake levels every year from the Parks Canada water management program (See under Water Levels), Mill Bay and Mud Bay become even more susceptible to conditions that worsen water quality.  These conditions include rich nutrient feeds from shorelines, the warming of the water column from hot sunny days, limited dissolved oxygen availability in shallow water, and the mixing of nutrients from the wind.  There are also man-made conditions that can adversely affect water quality.   From leaking septic tanks to shoreline development and clearing, these activities all worsen the lakes ability to absorb higher nutrient feeds.

The GBCLA is focussed on providing  educational assistance to lake residents and guests through our EduSocial progam on how to protect the lake and contribute towards a long term trend of improved water quality.    

Bobs and Crow Lake Catchment Reports

The individual reports for Bobs and Crow lakes break down the technical data by monitoring sites.   The data is quite technical and difficult to interpret for the average reader.   What is of most relevance is there are adverse long term trends putting the health of the lakes at risk relating to climate change, development and enforcement of existing regulations.  

What about E. coli?

E. coli

As part of the Rideau Valley Conservation Authority water monitoring program, E. coli counts are regularly taken and analysed on Bobs and Crow lakes.  The most recent bacterial counts are very low at most sampling locations and do not provide any indication of material risk for recreational use.

Residents who relies on lake water for drinking water, should consult with provincial Health units under "Useful Links" on the appropriate testing regime for their personal consumption.  

Flooded Septic Field