Gun Lake Septic Study

The Gun Lake Septic System Study was initiated in 2009 by the Gun Lake Ratepayers Association. The goal of the study was to better understand the effects of the residential septic systems on Gun Lake – a pristine, clear, glacier fed lake in the north east corner of the Squamish-Lillooet Regional District Electoral Area A - Upper Bridge River Valley). The initial study was made possible with the aid of a grant from the SLRD.

The study involved injecting tracer dye into a number of septic tanks and then tracking and recording the progression of the dye into the lake. Initial findings revealed that the expected dye plume did not appear in levels easily quantifiable, leaving the study team to determine what happened to the dye. Through excavations and research, it was found that the effluent from the septic systems was passing through a layer of coarse volcanic ash. Further research into this phenomena led the team to similar findings in a New Zealand study on the Transport and Attenuation of Microbial Tracers and Effluent Microorganisms in Saturated Pumice Sand Aquifer Material; in short, the ability of volcanic ash to absorb dye tracers and bacteria from sewage effluent.

Following the discovery of the New Zealand research, the Gun Lake Septic Study shifted its focus to understanding the absorption properties of the ash around Gun Lake. Preliminary results indicate that the soil has a similar ability to absorb microbes from the sewage effluent. This is an important finding as it shows that not only might Gun Lake have a natural filter for septic effluent in areas where ash exists in conjunction with the effluent flow, but the possibility of using the natural occurring substance in other communities as a filter for detrimental microbes could provide a substantial public and environmental health benefit.                                                                                                                              

There is need for further laboratory work, field studies and possible application tests on larger septic systems. Currently the Gun Lake Ratepayers Association is pursuing additional funding to support the continuation of this important work.