Algal blooms usually occur after hot weather and in the upper reaches of the river.

In 2005 and 2006 enormous blooms of these algae occurred in the Mediterranean sea.

Since its opening in 1994 no blue-green algal blooms have occurred.

The second bloom occurs around the holiday of Christmas.

The blooms usually occur at the end of the summer if there have been long hot spells and settled weather.

The bloom usually occurs in January, but sometimes as early as November.

"But it's not necessarily telling us why the bloom occurs to begin with."

Since 2007, a monitoring program has been in place to keep a check on algal levels and to notify authorities when blooms occur.

The most profuse algal blooms occur in the spring and early summer.

High nutrient levels and algal blooms occur in the lake from time to time.