The drought for much of the watershed ended with a deluge from Hurricane Floyd, which dumped a foot and a half of rain on some areas.

But Floyd’s fury was largely felt in Eastern Virginia and the Eastern Shore of Maryland. Western parts of the watershed got little rain, and drought — or near drought — conditions remain.

The deluge was a sharp contrast for the Bay, which had seen record — or near record — low flows from its tributaries almost every month since last fall.

The biological effects of the drought and Floyd in the Chesapeake won’t be clear for months. But scientists say it could be a mixed bag for the Bay.

For example, drought-related high salinities seemed to have improved oyster reproduction, or “spatfall,” in at least some tributaries. But the high salinities also improved conditions for the oyster-killing diseases MSX and dermo.

The freshwater from Floyd, though, may have pushed the diseases, particularly MSX, out of some areas. On the other hand, sediment flushed into the water could also cover oyster grounds with layers of silt.

In many areas, the drought produced excellent conditions for underwater Bay grasses. Dry conditions mean less sediment and nutrients are flushed into the Chesapeake, which results in clearer water.

Initial reports indicate that grasses in many areas were rebounding after a setback related to last year’s unusually high flows. In a few areas, though, high salinities were causing die backs of some freshwater species, such as wild celery.

It was too soon to tell whether Floyd reversed any of the grass bed gains, but cloudy, sediment-filled water was observed in many grass beds after the storm. On the positive side, scientists noted that the storm might have distributed seeds into previously barren areas, potentially preparing the way for future grass growth.

The high winds that accompanied Floyd may have help larval blue crabs return to the Bay. Blue crabs spawn near the mouth of the Chesapeake, but their larvae go into coastal waters before returning to the Bay. Climatic conditions are one of the most important factors in determining how many of the larval crabs return to the Bay to be “recruited” into the population.

Initial indications, according to scientists, are that this year’s recruitment may be high — potentially good news for a population that appears to have been low for several years.

Floyd’s heavy rains undoubtedly drove large amounts of pollution from streets and fields into waterways and the Bay, and monitoring crews were trying to assess the amount of pollutants that were pumped into the Chesapeake.

Pollution problems were not limited to runoff. In Baltimore, 24 million gallons of waste flowed into the Jones Falls beginning Sept. 16, after three pumps at a waste facility failed after a power outage. City workers were able to divert about 8 million gallons to the Back River, while 12 million gallons a day flowed into Jones Falls.

The timing of Floyd, arriving after the critical spring spawning season for fish and underwater grasses, may determine its ultimate impact. Hurricanes that hit the watershed in 1996 seemed to have little impact on the Chesapeake. But those storms hit the western part of the watershed hardest, while Floyd more directly hit the Chesapeake and near-Bay areas.

Until Floyd hit, streamflow into the Bay had remained low despite rain in late August. Freshwater flows in the Chesapeake averaged 8.8 billion gallons per day during August, about 56 percent below the long-term average for the month, according to the U.S. Geological Survey. That was the sixth lowest August river inflow on the Bay on record.

Streamflow figures for September were not available when the Bay Journal went to press.