Proposed development in Clarksburg does not pose a threat to Ten Mile Creek or the water quality and storage capacity of Little Seneca Reservoir, a Montgomery official told County Council members Monday.

But he said there is uncertainty about the cumulative impact on the reservoir of growth in the wider northern Montgomery area that includes Germantown, Hyattstown and Boyds. While the issue need not delay action pending before the council on Ten Mile Creek, he said it was a question that needed careful study.

“From a technical standpoint I think it would be very valuable,” said David Lake, manager of the water and wastewater policy group of the county’s Department of Environmental Protection. “I’d support a comprehensive drainage area and land-use study of Little Seneca Lake. Is it important between now and the time the council makes a decision on Ten Mile Creek? The answer from a technical position is no.”

In a series of joint work sessions, two council committees have been sifting through the scientific, legal and planning issues surrounding future development in Clarksburg.

The reservoir, created in 1985 as part of the region’s emergency water supply, is fed in part by the Ten Mile Creek watershed in the Clarksburg area, where Pulte Homes wants to build as many as 1,000 single-family houses and townhouses on 538 acres west of Interstate 270. On the other side of the highway, Peterson Cos., the developers of National Harbor, envisions 450,000 square feet of retail.

A final vote is expected sometime next month.

In 2012, the council asked the Montgomery Planning Board to examine the environmental impact of sediment and other pollutants from continued development around one of the county’s last high-quality streams. The planning board recommended significant cuts to the size of Pulte’s project and produced modeling showing that it would not be harmful to Ten Mile Creek.

But it never studied how increased runoff would impact the water quality and storage capacity of the reservoir. A coalition of environmentalists and former top county officials contend that the Pulte and Peterson projects posed unwarranted risks to a reservoir created because of regional concerns about drought.

“Are we rolling the dice?” That’s the question,” asked Council member Nancy Floreen (D-At-Large) chair of the council’s Planning, Housing and Economic Development Committee.

Floreen grew frustrated at representatives of County Executive Isiah Leggett, who has yet to take an explicit position on when, how, or if, a major reservoir study should go forward. Kathleen Boucher, chief operating officer for the Department of Environmental Protection, said Leggett was still “puzzling over” the issue.

“He’s not sure we’re rolling the dice,” Boucher.

Council members will continue their deliberations on Wednesday.