A school in the San Diego Unified School District has notified parents that test results show some water on the campus has been found to have "higher than allowable levels of lead."

The lead was found in three of ten water samples taken from the Emerson campus of Emerson-Bandini Elementary School, according to the district. The school is located in Southcrest, northeast of the connector between Interstate 5 and State Route 15. A district school and a charter school are co-located on the Emerson Campus.

Three weeks ago, NBC 7's Wendy Fry reported on concerns about a strange odor in the water at the school. At the time, district officials told NBC 7 they were alerted of the odor on January 26th. As a result, the district sent samples out for analysis.

A smelly odor in the drinking water at Emerson Bandini elementary school has prompted San Diego Unified Schools to provide bottled water to students. NBC 7’s Wendy Fry reports on the latest development in an alarming trend.

At the time, a district spokesperson said preliminary results indicated “some mitigation of the situation may be required.”

On Friday, Principal Heather Harris sent a letter to parents of students of the school and the charter, San Diego Cooperative 2.

In the letter, parents were told that a therapy dog refused to drink water from a sink in a charter school classroom.

The teacher saw "a sheen on the water that was similar to a sheen that can be seen when oil is on the surface of water," Harris wrote.

The district sampled water from several sources on the campus and results showed "levels of a contaminant that exceeded the state's allowable threshold," Harris wrote.

According to Samer Naji, a Facilities Communication Liaison with the school district, the contaminant in question is vinyl chloride (C2H3Cl) which is "generally related to plastic products and their degradation over time."

Naji said sample results showed a range from not detected to 2.35 micrograms per liter. The maximum contaminant level is .5 micrograms per liter.

The district's water provider, the City of San Diego, found similar results through its own testing.

"The contamination appeared to be isolated to the portable classrooms that house the charter school on the campus," Harris wrote.

Harris said workers replaced flexible lines leading from the wall to the plumbing fixture. That, along with no longer drawing water supplied through PVC pipe, seemed to fix the issue, she said.

While the school was testing for the strange appearance of the water in the charter school classroom, it was decided to also test for lead in the water.

Recently, there has been a series of instances in which parents and educators are concerned about school drinking water.

First, there was the discovery of lead in the drinking water at a San Ysidro elementary school.

Then, Warner Springs schools confirmed they are dealing with arsenic in the water there.

Soon after, the La Mesa Spring Valley schools' superintendent said water at all of its school sites was being tested.

In December 2016, the State Water Resources Control Board Division of Drinking Water required all community water providers test for lead in drinking water at K-12 schools.

SDUSD will begin testing the water in all schools for lead beginning April 4.

The work will begin in the southeast neighborhoods where some of the district's oldest schools are located.

The district will work its way north and west until they've completed the testing - which is estimated to happen around the end of the traditional school year in June.

According to the district, the finding of lead at Emerson-Bandini did not trigger the decision to test the water in all district schools. It was already in talks with the City of San Diego, the school district's water provider, to perform the testing.

Here is what parents can expect:

Five schools will be tested each day

Up to five samples will be taken at each campus.

Drinking fountains, cafeterias and food preparation areas may be included.

Testing will happen in the morning, before classes begin

City of San Diego will analyze the water samples

Results will be posted at this link.

The County Health and Human Services Agency has put together information regarding lead poisoning. You can find that here.