Salmon Creek Greenway swamped by Columbia’s overflow.Already-high water levels on the Columbia River are expected to climb higher today, pushing past the 16-foot flood stage in Vancouver. As a result, this week there is a possibility of flooding in low-lying areas near the river’s bank, according to the National Weather Service. About 3:45 p.m. Monday, the weather service issued a flood watch for the Columbia, saying it would affect some areas in Clark and Multnomah counties.“The river level in the Columbia River system will rise slowly over the next few days as increased snowmelt water from east of the Cascades reaches the lower Columbia River system,” the bulletin said. “Wet weather anticipated midweek may result in additional river rises late in the week.”Forecasts predict the river at Vancouver will surpass 16 feet and hover near or above that mark the rest of the week. If predicted showers materialize, high river flows could flood access roads and some low-lying properties. Rain figures into the forecast through at least Friday. The water levels will fluctuate about six inches during the high to low tide cycle. The river spent much of Monday about 15.7 feet above sea level, according to the weather service. Other local streams feeding into the Columbia are also high.