The Portland Water Bureau says it discovered two dead birds in a Mount Tabor reservoir while draining it in the wake of last month's boil-water notice.

A Water Bureau spokesman says the decaying carcasses may or may not have contributed to the positive E. coli test results that sparked a city warning May 23 to boil tap water before drinking.

The bureau says the dead birds could not have been the only reason for the positive tests—because they were found in Reservoir 5, while Reservoir 1 also tested positive and the two pools don't share water.

These are hardly the first dead birds found in Portland's open-air reservoirs. WW reported last August that crews patrolling the reservoirs had over five years logged six dead ducks, two dead crows and a dead seagull in the drinking water.

Here's the text of Water Bureau spokesman Tim Hall's announcement:

The Portland Water Bureau made a commitment that if we found anything while cleaning the two open reservoirs at Mt. Tabor, we would report this to you. This is to follow-up on the question of whether the bureau has been able to identify the cause of the Total Coliform E Coli positive water samples from two weeks ago.As we noted during and following the boil water incident, we did an environmental scan around the reservoirs and at the Water Quality Sampling Station at SE 2nd Avenue and SE Salmon Street when the positive results came back. We found nothing that could be cited as the cause for the positive test results.We also indicated that we would look for obvious potential causes when we drained and cleaned the reservoirs. Reservoir 1 was drained and cleaned with no evidence of obvious contamination. However, when staff drained and began cleaning Reservoir 5 last week, they discovered a dead bird at the bottom of the reservoir at the outlet’s “mud ring” – a concrete curb designed to hold back natural sediments (mud) and debris. Water flows over the mud ring and into the outlet pipe, but the mud and debris get hung up on the curb. The bird was found at the base of the ring. The decayed remains of a second bird were also found stuck to the liner on the other end of the reservoir.We cannot determine with certainty that the dead birds were the cause for the positive tests from Reservoir 5, but again, we did promise to let you know if we found anything. Since the pipe connection between Reservoir 1 and 5 was closed at the time, we can state with relative certainty that the Reservoir 1 positive test result was not caused by the dead birds found in Reservoir 5.Thank you.