The abnormally dry rainy season of 2007 is taking its toll on St. Helena's water supply.

On Tuesday, St. Helena Public Works Director Jonathon Goldman will recommend the City Council limit which days of the week people can irrigate and water their lawns.

Bell Canyon Reservoir, which serves St. Helena water customers, was at 74 percent of capacity in mid-March. One of the triggers for what Goldman called Phase II conditions is that the Bell Canyon Reservoir is less than 75 percent full on June 1.

"Given that we're below 75 percent now, I think it's fairly likely that we'll be at 75 percent or below on June 1," Goldman said. "Now is the time to be conserving rather than waiting until June."

Phase I conditions already in effect encourage water customers to conserve voluntarily. Phase II includes all Phase I's voluntary conservation measures, plus a system requiring even- and odd-numbered addresses to water on alternating days.

Water customers caught violating the restrictions could risk having their water rationed.

Other water use restrictions will be detailed in city water bills and public notices.

The city's problems would be worse if not for the water being purchased from the city of Napa under a deal forged in September. Since Feb. 27, Napa water has been pumping into St. Helena's water system through the Rutherford booster station at a rate of about 12.4 acre-feet per week -- 400 gallons per minute.

Goldman hopes to be able to continue to draw water beyond April 30, the cut-off date specified in the city's contract with Napa. By that time, he expects to have received 120 acre-feet from Napa that otherwise would have come out of Bell Canyon Reservoir or local groundwater wells. The contract allows the city to take up to 300 acre-feet under this year's conditions.