Guidelines to safe swimming

Safe to swim? Not at the murky William Birch pool, according to Horizons' guidelines. PHOTO/FILE

The time has come for swimming.

Wanganui highs have been at or above 20C since November 17 and people are taking to the water.

Even the water temperature at Wiritoa Lake has been at 20C the last two weeks.

Algae levels are creeping up at both Wiritoa and Duddings lakes.

They are not toxic, but swimmers should avoid going in where there is a surface scum because that means algae numbers are especially high.

Horizons Regional Council will be testing water at the region's main swimming spots weekly until April. Its website gives the latest health ratings - green for safe swimming at Kai Iwi and Castlecliff beaches and the Whanganui River at the town bridge, amber for swimming that "should be satisfactory" at Duddings and Wiritoa lakes and red for swimming that could be a health risk at the Mowhanau Stream at Kai Iwi Beach.

But it doesn't take a scientist to say whether it's safe to swim or not, Horizons' water spokesman Barry Gilliland said.

The ratings are only changed weekly, so its also important to make a call on the day.

The website gives some general guidelines for safe swimming:

If the water looks clean and clear, and it is a sunny day, it should be safe to swim.

It's safest to wait three days after rain before swimming at river swimming spots.

You and your dog should avoid using the river if there are musty-smelling, black, slimy, mat-like growths on river bed stones.