BELLINGHAM - The Whatcom County Council has extended the moratorium banning development on small lots around Lake Whatcom at least 14 times. The six-month extension approved Tuesday, Jan. 15, may have been the last.

Council accepted a rewritten version of the moratorium that could be a glimpse into a future of stronger water-quality protection for Lake Whatcom. For the first time, the moratorium allows building on lots smaller than five acres, but it also sets a strict new rule, suggested by the Department of Ecology, requiring no man-made phosphorus discharge into the lake.

Officials involved in Tuesday night's debate implied it's a matter of when, not if, the county adopts the state's zero phosphorus standard for all Lake Whatcom developments. Council members appeared ready to adopt this standard within the next six months. If the zero-discharge rule is adopted, the moratorium on small lots around Lake Whatcom can be lifted, officials said.

Before the 6-0 vote on the moratorium (council member Ken Mann was absent), some council members were skeptical of the new allowance for one-acre lots on properties zoned for five-acre development. The number of homes on the properties wouldn't increase; houses could be built on clustered one-acre lots, with a large piece of property left open. But council members Barbara Brenner and Carl Weimer said existing rules might not properly limit phosphorus in stormwater runoff from the smaller lots.

"We don't know whether we're going to allow more phosphorus to come off these lots than what the Department of Ecology has asked for," Weimer said.

State and county officials consider phosphorus a major threat to Lake Whatcom water quality. Phosphorus is found in fertilizers, laundry detergent and human waste, so it can drain from lawns and failing septic systems into lakes. Phosphorus leads to reduced oxygen in lake water, threatening aquatic life. The chemical also requires extra treatment to be removed from drinking water. Lake Whatcom supplies water to about 100,000 residents.

Before stating his support for the zero-discharge rule on one-acre lots, council member Sam Crawford said a small part of him wondered if the council should approve something now that might not be adopted more broadly later.

"Is that really reflective of this future ordinance that we haven't yet adopted?" Crawford said. "It's reflective of my understanding of where we're headed."

Reach Ralph Schwartz at 360-715-2289 or ralph.schwartz@bellinghamherald.com. Read his politics blog at blogs.bellinghamherald.com/politics or follow him on Twitter at @bhamheraldpolitics.