Seen on waterfront Tuesday evening (update, 12 photos)

12:27 p.m. update:

The Ministry of Environment says officials were on site this morning and found trace amounts of the dye in the water.

"It is harmless and it is approved for use in drinking water," said Kate Jordan, an MOE spokesperson.

10:30 a.m. update:

The developer behind the Riverwalk Condominiums project at the old hospital site confirmed this morning that the substance seen entering the river is a biodegradable product being used for engineering purposes.

AECOM is using the dye to determine the route of sanitary and storm sewer services for the site, said Amit Sofer, president of TVM Group.

"The city uses the same product is what I'm told," said Sofer.

Sofer said he was alerted to the discharge last night as well.

The company is expected to break ground at the site on May 23.

Original story:

A loyal SooToday reader who doesn't want to be identified sent us a tip that some mysterious green substance was leaking into the St. Marys River near the old Plummer Hospital.

We went to check on it for ourselves and found the stuff flowing out of a heavily corroded pipe in waves.

Our tipster said he notified the Ministry of the Environment and that it was investigating.

The photo he sent us at 6:15 p.m. on Tuesday shows the green substance along the shore but no orange paint on any rocks.

When we found the site at about 8 p.m., a rock above the remains of the old culvert was painted bright orange and there were orange marks sprayed on the shore leading westward up to and over the John Rowswell Hub Trail.

SooToday will be following up on this story as more information becomes available.