Brentwood Bay sees elevated bacterial levels during heavy rain

Monitoring work over the winter indicates times when beaches should not be used.

Testing around Brentwood Bay indicated times of high bacteria counts in the winter.

With an unusual summer of drought and a winter of short, heavy rainfall, the waters around Central Saanich have seen elevated bacterial levels — particularly at the Brentwood Bay beach near the marina.

The District of Central Saanich heard the results of near shore marine testing for both Brentwood Bay and Saanichton Bay (at the east side of the island, adjacent to Tsawout).

Supervisor of the Integrated Watershed Management program for the Capital Regional District (CRD) Dale Green presented the results.

Some of the services they provide throughout the program for Central Saanich are around storm water monitoring, watershed protection, education and more. They work closely with the District’s engineering department.

“Historically the role of this program was to test storm water discharges in order to find levels of contamination that indicated infrastructure or other issues and then we’d investigate further to find sources so that municipal staff could undertake repairs,” said Green at Monday night’s committee of the whole meeting.

He said in some cases those sources tend to be septic tanks, in which case Island Health would follow up.

With a limited budget, Green said they selected certain beaches around the Capital Region that have a history of high bacteria levels, a lot of public use and are easily accessible.

Last winter they sampled every two weeks, one-and-a-half metres off shore. They measured bacteria levels.

Ten samples were taken in Central Saanich locations.

In Saanichton Bay, samples met the Canadian recreational guidelines for primary contact, however Brentwood Bay’s bacteria levels in those tests, exceeded the guidelines. Green said, however, only two of the tests taken exceeded what they call the single sample guideline for the Saanichton Bay site.

The guideline is 70 bacteria per 100 millilitres of water. Brentwood Bay exceeded the guideline on seven out of 10 samples.

“Further to that what we did is an analysis called bacterial source tracking and we weren’t able to do that at the Saanichton Bay site due to conditions,” said Green.

In Brentwood Bay however the testing indicated the bacteria sources were human, ruminant and dog, which he said is quite a widespread mix.

The ‘human’ sources, he said, are sewage systems, failing infrastructure or infrastructure that needs maintenance and septic tanks.

Ruminants refers usually to an agriculture source of contamination, while dog sources are pretty widespread.

“It’s important to note that through the winter we targeted heavy rainfall events, so some of these 24 hour periods we sampled had between 13 and 45 millilitres of rain, which is pretty significant,” he said.

Green said the area went through a drought in summer and had a winter which saw very high peak storm events.

He said during those storms is when it’s really important for them to be out to see what conditions are like.

An additional set of samples will be taken this winter.

“Already this summer seems to be a little bit different than last year, so hopefully that continues into the winter.”

More importantly, Green said they want to verify some of the results they got last winter and do some sampling 24, 48 and 96 hours after rainstorms to see how long these bacteria levels stay elevated.

“We’re also going to add a few sites we were unable to do such as, with their approval … beaches along Tsartlip and Tseycum First Nations and we’ll collect a bit more information along that shoreline to give them some information about the safety of the contact with the water.”

Area municipalities, Island Health and the CRD will meet within the next month to talk about strategies for advisories or public education.

Because some of these bacteria levels exceeded the recreational guidelines, Green said, Island Health will want to ensure people use caution when coming in contact with the water.

Councillor Alicia Holman was concerned about Brentwood Bay, asking what can be done immediately.

Green said the entire 2015 sampling program will go through the Peninsula Wastewater Commission.

Prior to that, they are working with the District’s engineering department on strategies for the next sampling cycle.

Green said what would make sense is to do some upstream investigations and begin trying to locate the sources of contamination.

“Part of the challenge with that catchment is because we saw (multiple) sources …” he said.

Coun. Bob Thompson wanted to know if the sources are 100 per cent land-based or if there is some impact from illegal discharge of effluent into Brentwood Bay from boats.

Green said he is unsure of that at this point, adding where they tested was very close to the shoreline and at a time when stormwater discharges were quite heavy.

If there was any contribution from boats, he said, it would be minor.

The District will wait for the CRD’s reporting process to go through the Peninsula Wastewater Commission.