The Coquihalla Highway was closed on Wednesday by a mudslide. (CBC)Some highways remain closed and several communities struggle to hold back flood waters across southern B.C. on Thursday morning as crews deal with the aftermath of two days of heavy rain falling on top of melting snow.

The Coquihalla Highway 5, which connects the Vancouver area with the Interior, remained closed in both directions near Hope after a mudslide shut down the route on Wednesday morning.

Officials were concerned about more slides coming down from high on the steep mountain slopes above the route and were not confident they would have the highway reopened by noon PT.

On Highway 1, crews managed to reopen one section near Hope that was closed by a mudslide and another between Golden and the Alberta border that was closed due to avalanche risk on Thursday.

But Highway 1 remained closed between Craigellachie and Revelstoke because of high avalanche risk as of 11 a.m. PT and officials were uncertain when the route would reopen.

Further south, the third route connecting Vancouver with the southern Interior was reopened through Manning Park, but high avalanche risk was keeping it closed in the Christina Lake area and over Kootenay Pass.

Elsewhere in the Interior, Highways 6, 23, 31 and 31A were also closed because of high avalanche risk.

Meanwhile on the southwest coast of Vancouver Island, Highway 14 remained closed by a mudslide 35 kilometres west of Sooke, leaving the town of Port Renfrew with limited access via a secondary route through the Lake Cowichan area.

Flooding hits Fraser Valley

Around the Lower Mainland and the Fraser Valley, there were widespread reports of flooding closing local roads and damaging properties, particularly in the Fraser Valley and Coquitlam.

Many Fraser Valley streets and properties were under water after heavy rain quickly melted a large amount of snow. (CBC)One of the worst hit areas was the city of Chilliwack, where crews were working round the clock to deal with drainage problems that were threatening to flood the downtown core.

Staff reported there were at least 12 mud and debris slides on several hillsides, numerous incidents of local flooding and flooded basements due to plugged culverts, road and shoulder washouts.

Nikita Neel's home in the low-lying Greendale neighbourhood was one of about 40 that had basements flooded.

"It was eight inches of water in our basement, and the whole backyard is flooded," she said.

But it was not just the floodwater that made the situation terrible.

"Because our septic field ... our tank is below our back deck, so now that is leaking. The wall is right by our basement, so that's leaking into our house. The basement smells of septic," Neel said.

At least three homes on Vedder Mountain Road were also hit by the mudslides in that area and the residents were advised to leave in the interest of safety.

Localized flooding also resulted in a number of road closures including:

• Vedder Mountain Road.
• Sections of Keith Wilson west of Hopedale.
• The intersection of Adams and Hopedale.
• The intersection of Sumas Prairie and South Sumas.
• Shrewsbury Road.

Sandbags are being made available to residents free of charge to assist in flood control efforts on private property.

In Abbotsford officials were keeping a close eye on the level of the Nooksack River and staff were reporting flooding in the following areas:

• Norrish Creek Road.
• Clayburn Village.
• Lower Sumas Mountain Road.
• Fishtrap Creek Park, north and south of the creek.
• Along the banks of the Nooksack River.

A high streamflow advisory remained in place, but provincial officials reported that local rivers had reached peak levels overnight and were expected to fall throughout the day Thursday.

Motorists everywhere were advised to use caution and watch out for the large number of potentially damaging potholes that three weeks of freezing and thawing weather left in the roads.

The heavy rainfall was expected to ease on Thursday, but more rain is expected for later in the week.