Bacteria that may cause illness has increased in popular Shuswap Lake in flooded swimming areas but remains within national standards for recreation, a public health official said Friday.

Dan Ferguson, assistant director for health protection with Interior Health Authority, said sampling has shown what he called “slightly higher” levels of fecal coliform.

Typical Shuswap background levels are 10 colonies of e-coli found per a 100-millilitre sample.

“Now we’re up to 50,” he said.

National guidelines for recreation deem a maximum limit of 200. At that level one in 100 swimmers would be expected to suffer illness.

Columbia-Shuswap Regional District advises “swimmers should make efforts not to ingest lake water and children should always be closely supervised.”

Higher bacterial counts along the foreshore are caused by increased road wash material running into the lake, flooded streams carrying agricultural waste and flooded septic fields — some of them historic systems no longer in use.

Ferguson said there is greater risk for potential swimmers from debris in the water, deadheads for example, and hidden concrete and steel that may be normally above surface but is now lurking below.

Beyond any risks of water-borne illness, many lake areas remain flooded as waters slowly recede from a 40-year high reached last week.

Wendy Byhre, a spokeswoman with Shuswap Tourism, said an erroneous television news report that ran in the Lower Mainland about risks of swimming dropped tourism visits substantially over the July long weekend.

Visitor drop-in numbers at a roadside tourism office in Salmon Arm, an indicator of overall traffic, dropped by 40 per cent.

“It (lake levels) are declining now. We hope to see more people in the region this week.”

Byhre said visitor numbers in the North Shuswap do not seem to be down as much as the Salmon Arm numbers.

While many beaches remain flooded, a public beach near Quaaout Lodge has sandy areas exposed. Grassy areas in public parks are also available.

“There’s lots of alternatives.”

Public boat launches remain closed. Byhre said, however, most private marinas are open.

There are no boating restrictions. Boaters are cautioned about creating wakes that could wash over protection for low-lying cabins and homeowners.

Most Shuswap waterfront owners have surface intakes for household water. Ferguson said IHA recommends that people boil untreated drinking water, whether now or in the middle of winter.