Five coastal areas around the Wellington region remain unsafe for swimming today after heavy rain sent harmful bacteria levels soaring.
Oriental Bay, Freyberg Beach and Frank Kitt's Lagoon, which were all on the no-swim list earlier today, have since been given the all-clear after bacteria in returned to safe levels.
However, five sites, including Lyall Bay and Wairarapa's Riversdale Lagoon, still had unsafe levels of enterococci bacteria.
Greater Wellington senior environmental scientist Summer Greenfield said the large number of unsafe sites was the result of about two days of persistent rain.
All of the council-monitored sites would hopefully return to normal in the next 24 hours or so, she said.
''Most of the sites that have shown up [as unsafe] this week are in urban areas where the heavy rain washes contaminated water off the streets and into the harbour ... you also get storm water and sewer overflows.''
Enterococci bacteria itself was not harmful but its presence often indicated the presence of other harmful bacteria such as E coli, campylobacter and salmonella, Ms Greenfield said.
The council's general warning is to not swim anywhere for 48 hours after heavy rain.
Meanwhile, toxic algae continues to plague the Masterton's Waipoua River.
The algae is forming brown or black clumps on the riverbed, which can kill livestock and dogs.
The clumps often wash up on the river's edge where dogs can easily come into contact with them. When dogs ingest the algal mats, they can die quickly and painfully.
Warm weather and a lack of heavy rain in the Waipoua catchment has caused the increase in algae.
Ms Greenfield said the river was still waiting on a large amount of rain to flush the algae out to sea.
''For humans, the problems we tend to see are more skin rashes and the odd gastrointestinal upset but there is the same potential for fatalities. But it has to be ingested for that to happen.''
''Toddlers and babies paddling on the river's edge are the highest risk group.''
Unsafe areas at 4.30pm were:
- Lyall Bay
- Island Bay
- Sorrento Bay
- Rona Bay
- Riversdale Lagoon
For a regularly updated list of bacteria affected beaches, see the regional council's website.
- The Dominion Post
Was the weekend's rain welcome relief for your garden/farm?Related story: Yesterday's drizzle no drought breaker for Wellington, Hawke's Bay