Water conservation measures and the threat of rationing have made St. Helena residents aware of the drought’s effect on Bell Canyon reservoir. But the city’s lower reservoir is hurting even more.

Spring Mountain Vineyard and Robert Louis Stevenson Middle School have agreements with the city to use water from the lower reservoir. After the last rainy season yielded little rainfall, Public Works Director Jonathon Goldman told the vineyard and school that 2007 would be a difficult year.

Unlike typical years when the lower reservoir spills over, it never got beyond 38 percent of its 160-acre-foot capacity this year, said Ron Rosenbrand, vineyard manager at Spring Mountain Vineyard.

According to Rosenbrand, the drought will result in a 10 percent to 15 percent crop reduction at Spring Mountain Vineyard, although quality is not expected to suffer.

“In the last two years we’ve used about 50 acre-feet,” Rosenbrand said. “But so far through this July we’ve used about 10, and the reservoir’s almost empty.”

Spring Mountain Vineyard’s 225 acres account for about 25 percent of the vines in the Spring Mountain American Vitivultural Area.

The shortage is exacerbated by Spring Mountain Vineyard’s steep slopes of up to 50 percent. Hillside vineyards are usually affected more by droughts than valley floor vineyards because they have less topsoil and more rocks, limiting the moisture the soil can hold, Rosenbrand said.

He said that even if the vineyard switches to the Bell Canyon reservoir, it would still be subject to water restrictions, and would have to pay about five times what pays now.

RLS Middle School isn’t hurting as bad. According to Principal Mary Allen, irrigation has been reduced — except at the school’s field, which continues to be watered at a normal rate because it’s used by the entire community. Even the St. Helena Saints have used the field for practices while the high school’s field is replaced.

“We have some dry spots, but everybody’s had to cut back, and that’s OK,” Allen said. “Overall it hasn’t been that bad.”

The lower reservoir wasn’t always so dependent on the whims of Mother Nature. The city regularly diverted water from York Creek into the reservoir until the mid-’90s, when the Department of Fish and Game imposed new regulations.

That stretch of York Creek is one of the most popular in the county for steelhead, and the regulations were aimed at protecting that population. The city would have been allowed to divert water to the reservoir only when the creek’s flow reached a certain level, and a $500,000 facility with fish screens would have had to be built to protect the steelhead.

“The only time we would have been able to divert was during the wet season when, in normal years, the reservoir fills by itself,” Goldman said. “We wouldn’t be allowed to divert water into the reservoir now.”

Given the cost of the necessary facility and the prohibitive regulations, the city opted to discontinue the diversion.

This has been the first drought year since those diversions stopped, Rosenbrand said.

He said he’s impressed with how well the vines have held up given the reduced irrigation. A second consecutive dry year might damage them further, but Rosenbrand isn’t overly concerned with the forecasts predicting another drought.

“I’m not counting on a drought in ‘07-08,” he said. “But if it happens, there’s not a whole lot we can do. You have to roll with the punches.”

Keeping the lower reservoir filled is complicated further by the city’s water rights, which require the city to use the water, not just keep it for the sake of habitat or appearance, Goldman said. In rainy years, the reservoir’s leftover water is made available for construction and irrigation purposes within the city.

This year, that won’t happen.