Via its At Your Service website, Seattle Public Utilities announced on Friday that the newly buried reservoir in Highland Park – formally known as West Seattle Reservoir – is now officially “in service.” SPU had told WSB in May that the reservoir was being filled – it’s 30 million gallons, half the size of the old open one. The utility showed the media (and then-mayor Greg Nickels) last fall what it looks like underground; the 20-acre park that’s being created because of the undergrounding is now in the next design phase after another thumbs-up from the Seattle Design Commission (WSB coverage here).