Study proves that Cowichan Lake is no toilet

Tests performed on Cowichan Lake water last year prove that it’s fairly clear of fecal coliform, which is bacteria that originates in feces.

  • Jul. 18, 2011 6:00 p.m.
It’s not just humans that have an effect on fecal coliform levels on Cowichan Lake. Even this deer

It’s not just humans that have an effect on fecal coliform levels on Cowichan Lake. Even this deer

Tests performed on Cowichan Lake water last year prove that it’s fairly clear of fecal coliform, which is bacteria that originates in feces.

But it’s not entirely crystal clear.

“It’s not disastrous results, but high enough that people shouldn’t be drinking lake water without treatment,” Cowichan Lake and River Stewardship Society member Gerald Thom said.

The sampling was done by the society, in conjunction with the Ministry of Environment, which has been charged with making sense of it.

Sampling was done at 12 sites around Cowichan Lake, over 10 weeks in 2010.

Five weeks’ worth of sampling was done from July to August, during which time water is the lowest and therefore the least dilution is taking place.

Another five weeks of sampling was done from October to November, when the highest level of drainage into the lake occurs.

“The fecal coliform, or e-coli, are usually pretty low, below detection levels,” Ministry of Environment environmental impact assessment biologist Deborah Epps said.

There were, however, several spikes where sites exceeded maximum allowable fecal coliform levels, though most averages remained well below the danger zone.

The province has declared that the maximum healthy level of fecal coliform is anything less than 10 colony forming units (CFU) per 100 ml for drinking water, and 200 CFU/100 ml for recreational purposes.

Below detection levels includes anything under one, Epps said.

The Cowichan Lake Marina area saw levels range from five to an extremely high spike of 1,400; the highest numbers being isolated incidents.

“That’s one that’s worth looking into,” Epps said, of the marina.

There could have been many causes of the high spikes in fecal coliform CFU results, from wildlife to a boat owner dumping waste, and until it’s investigated it’s all speculation.

Another area that tested high for fecal coliform CFU is the head of the south arm of Cowichan Lake, by the weir, which saw a range of below one to about eight fecal coliform CFU / 100 ml, which is still within a safe range for drinking water.

The western edge of Youbou also saw some high numbers, which could be attributed to the area’s septic systems.

The average fecal coliform level there was eight fecal coliform CFU / 100 ml.

One potential sign of a body of water with a high fecal coliform count is its cloudiness, or turbidity.

This cloudiness isn’t necessarily a result of feces, but of various forms of sediment. Fecal coliform attaches itself to dirt, and is transported down land, or water, to the lake. This fecal coliform can be related to either human or wildlife activity.

One solution would be clearing up the on-land drainage into the lake.

“Just in the process of stopping sediment, you’re stopping everything else,” Epps said.

Related to this are riparian zones (protected shoreline land).

“Riparian zones work as filters to reduce these sediment inputs into the lake” Epps said.

With the report now complete, Epps said that it will be posted online in the very near future for all to see, at

“This report is setting water quality objectives for Cowichan Lake,” Epps said. “You’ve got the data, and the numbers, then it comes out of my hands.”

The tests were limited to Cowichan Lake, and did not include the Cowichan River.

Now, it’s up to government and environmental regulators to determine what should be done with these results, and what, if any, action should be undertaken.

“There needs to be new investigations on inadequate septic systems,” Thom said.

Much of Cowichan Lake west of the Town of Lake Cowichan doesn’t have adequate sewer systems.

This excludes new developments, such as Woodland Shores, Creekside, and others, where the Cowichan Valley Regional District has required  the installation of modern sewer systems.

The upcoming Youbou Lands development will also include the development of a sewer system.

There are still lots of older established areas that don’t have sewer systems, and still rely on septic systems, Thom said.

“I believe that all residents within striking distance of the lake should be on a sewer system of some sort, because 50 per cent of septic systems fail within 10 years,” Cowichan Lake South/Skutz Falls area director Ian Morrison said.

It’s not just septic systems failing, but human nature that makes septic systems insufficient.

“It’s a natural tendency for people to not do maintenance on septic tanks, because it’s out of sight out of mind,” Morrison said.

Honeymoon Bay is entirely on septic service, and Mesachie Lake has an out-dated sewer system that needs replacing.

The tax burden on installing a modern sewer system at either community would be cost-prohibitive due to their small populations.

As such, Morrison’s already held preliminary discussions with major property owners in the area, to have them help pay for the systems.

In exchange, they could get higher density zoning on their properties, which would create a win-win situation for all involved.

Government grants will also be looked into.

Senior environmental health officer with the Vancouver Island Health Authority Craig Nowakowski said that although people may still install septic systems on the island, there are some restrictions.

“We have our regulations. We want to protect them from contaminating the lake,” he said.

There are some variances, but on average, septic tanks must be at least 30 meters from the flood plain. Even so, there is the potential for contamination.

“As systems grow older, they give out. It depends on if they’ve been constructed and maintained properly,” he said.

Modern sewer systems are without a doubt better than septic systems, Epps stated.

The Vancouver Island Health Authority takes their own regular water samples of Cowichan Lake’s beaches, which routinely test within safe ranges for fecal coliform. Usually, whenever numbers are high on beaches, it’s a result of geese and ducks, which like to hang out at beaches.

“Cowichan Lake’s pretty good because it turns over pretty fast,” he said. “It’s not like it’s a stagnant body of water.”

Another fecal coliform test, similar to the one taken last year, will be done in a few years. A similar such test was done in 2008, which yielded very similar results to last year’s, Epps said.