Two developers are proposing massive projects in rural Clarksburg, sparking an uproar among Montgomery County environmentalists.

Peterson Cos., the company responsible for National Harbor and downtown Silver Spring, has been discussing with lawmakers plans for a hotel, premium retail outlets and some form of residences to the east of I-270 in Clarksburg, multiple county sources say.

Former Montgomery County Planning Board Chairman Royce Hanson, who has been involved with Clarksburg development plans for years, said the plans include about 1,000 units of residential and roughly 500,000 square feet of commercial space, including the hotel, retail and possibly offices.

Peterson Cos. Senior Vice President of Retail Taylor Chess declined to reveal the details of the plans, saying only that the firm "has met with community leaders and organizations to seek their input on a variety of scenarios consistent with the Clarksburg Master Plan," and plans to release details in the coming months.

Pulte Homes Corp., meanwhile, hopes to develop roughly 538 acres on the west side of I-270, according to a recent memo from the developer's attorney to County Executive Ike Leggett.

A representative of Pulte Homes could not be reached for comment.

Both developments are proposed for the area around Ten Mile Creek, which connects to the county Agricultural Reserve and has been designated as a protected resource by the county. On Oct. 9, the County Council is expected to decide whether development can move forward with a relatively minor regulatory change that would allow a sewer system there or whether development would require a more lengthy approval process through the county Planning Board.

"It shouldn't be a controversial issue," said Hanson.

The creek feeds into Little Seneca Lake, a backup water supply for the region, he said. "Ten Mile Creek is probably the single best stream left in Montgomery County."

The Audubon Naturalist Society and the Montgomery Countryside Alliance are fighting for a lengthy process, which would require additional study of the area to determine the best way to protect the watershed.

"This is not a question of people throwing their arms up and saying, 'No development,' " said Caroline Taylor, Montgomery Countryside Alliance's executive director, emphasizing that the group simply wants more study to be done.

Meanwhile, the developers are urging the shorter regulatory process.

Deciding how much development to allow in the area has been a heated debate in the county since the 1990s. A decision on the Ten Mile Creek tract has been pending since 2010. Leggett called the delay "unfair" and said it was time to move forward.

"Ten Mile Creek is one of the few naturally reproducing trout streams in the county and one of our most pristine water bodies," he wrote in a memo last week. "I also believe we must provide the residents of the Clarksburg area with the essential amenities and infrastructure that they need."