Algae bloom prompts warnings at city pond

? Signs warn people to keep themselves and pets out of the water.

There?s a reason it?s called ?blue-green? algae, as last week?s major bloom in the Hillsboro Heights water-retention pond illustrates. The top photo, taken Aug. 25, is from the ditch along U.S. Highway 56 that receives overflow water from the pond at its northeast corner. Free Press photo by Don Ratzlaff

The city of Hillsboro has posted warning signs at the retaining pond in the Hills?boro Heights development after discovering a major blue-green algae bloom last Tuesday morning.

The signs warn of potential sickness in human and pets if they come in contact with the pond water.

The most visible evidence of the contamination was at the overflow at the northeast corner of the pound, where the thick, blue-green sludge-like bloom was plainly visible and odorous.

Free Press / Don RatzlaffLater in the week, Mor?gan Marler, senior water treatment technician for the city, initiated a fire-hydrant flush that pushed most of the visible evidence further down the drainage path.

?I thought the bright blue color might be attractive to kids,? Marler said. ?That?s really why we were trying to push it out of there.

?Unfortunately, that pond has become a fishing spot,? she added. ?We really want people to stay away and to also keep their pets away.?

If people choose to take fish from the pond, they should clean the fish well and discard the guts.

If people or pets come in contact with the water, they are advised to wash with clean water as soon as possible.

The city posted signs later in the week that warn people to keep themselves and their pets away from the pond water.  Free Press photo by Don Ratzlaff Marler said the local pond suffered a similar fate for similar reasons Marion Reservoir has experienced blue-green algae blooms off and on for several years now.

?My theory is that there is excessive phosphorus and nitrogen entering the pond from the drainage area it encompasses,? Marler said. ?The excess nutrients, along with the warmer water temperature and the hot, sunny weather, make it a prime blue-green algae environment.?

Marler said the newly posted warning signs likely will be left up permanently because it?s unlikely that the blue-green algae can be flushed out entirely, even with significant rains.

?It?s a very, very deep retention pond,? she said. ?And it?s probably not going to clear out once you have those nutrients in there and once you have the spores from the algae in there. They?ll just keep blooming and blooming.

?We haven?t really talked about it, but treating the pond might be a possibility, depending on what the council wants to do about it.?

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