It almost sounds like you have a cyanobacteria/blue-green algae outbreak:
Dense blue-green algae blooms may make the water look bluish-green, or like green pea soup or turquoise paint. Very dense blooms may form solid-looking clumps.
Fresh blooms often smell like newly mown grass, while
older blooms may smell like rotting garbage.
Causes
One key factor contributing to the growth of blue-green algae is the amount of available nutrients such as
phosphorus and nitrogen.
Blue-green algal blooms can be caused by agricultural and stormwater runoff as well as leaching from septic systems.
In Ontario, phosphorus tends to be the nutrient that influences the growth of algae.
If you spot it
Take a cautious approach, as some varieties of
this algae can produce toxins that are harmful to both humans and animals.
If you suspect a blue-green algal bloom:
- assume toxins are present
- avoid using, drinking, bathing or swimming in the water (call your local health unit for swimming advisories)
- restrict pet and livestock access to the water
If this is the case, getting rid of it is extremely difficult! Sometimes not even bleach will kill it. You might have to scrape out that area and fill it with sand or something else well draining as well as use some kind of bacteria killer...