A federal regulator says Alberta needs to do more work to assess the environmental impacts of the proposed Springbank reservoir — a major project designed to protect Calgary from floods — as the initial submission was deficient in several key areas.

"We found, at this point in time, the environmental impact statement did not conform with our … guidelines that we issued in August of 2016," Shelly Boss, project manager with the Canadian Environmental Assessment Agency (CEAA), said Monday.

Alberta Transportation submitted the report in mid-October and the agency is now asking the province to submit a "fully revised" report with more detailed information in a variety of areas.

"In general, the level and breath of information ... needs to be increased," the regulator told the province in a letter.

Boss said "it's not unheard of" for the agency to make such requests of project proponents.

"This development is not unanticipated and is part of the due process of the federal regulator," Alberta Transportation spokesman Adam Johnson said in an email.

"The Government of Alberta fully respects the regulatory process and takes CEAA's advice seriously. Alberta Transportation and its engineering consultant are currently reviewing the list of requested details and will comply with CEAA's requests for further detail."

What's missing?

The agency is looking for more information on groundwater impacts, more detailed estimates of how much dust will emanate from sediment deposits once water recedes from the reservoir and more description of how the project will impact fish, migratory birds and at-risk species in the area.

It is also asking Alberta Transportation for more information on public engagement activities and consultations with Indigenous groups.

In addition, the regulator wants more information on various malfunction scenarios and contingency plans in the event of a reservoir failure.

The assessment can't move forward until the CEAA gets that information.

"We need that information in order to commence our technical review," Boss said.

Calls to revisit McLean Creek option

An organization named Don't Damn Springbank — comprised of landowners whose properties would need to be bought (or expropriated) in order to make way for the reservoir — said Monday the regulator's request for more information raises questions about how thoroughly the province has thought this through.

"It's very consistent with what our group has been saying since Day 1," said Ryan Robinson, who owns land in the affected area.

"There are serious concerns with the government's plan."

Robinson said he and other landowners still want the province to go back to a different proposal for flood mitigation — a dry dam in the McLean Creek area of Kananaskis Country.

McLean Creek Dry Dam

A visualization of what the proposed (and since abandoned) McLean Creek dry dam would look like when holding back water. (Government of Alberta/YouTube screenshot)

"We are 100-per-cent for mitigation," he said. "We support our neighbours in downtown Calgary just as much as anyone."

Robinson said a dam at McLean Creek would protect more communities, as it is located farther upstream along the Elbow River, and not require the use of private land.

The previous Progressive Conservative government considered the McLean Creek option for a time but abandoned it in September 2014. Critics had raised concerns about environmental impacts in the Kananaskis area and safety concerns should the dry dam fail.

Former premier Jim Prentice described the Springbank option as "the most cost-effective, most environmentally responsible way to get flood protection for Calgary." The NDP government that was elected in May 2015 continued to press forward with plans for a reservoir there.

What's next?

Boss said the project, from the federal regulator's point of view, is on pause until the additional information is submitted.

The province had no immediate estimate as to how long it will take to gather and submit that information.

"Right now we are assessing what the federal request for information will require for the project, and it is too early to tell what that timeline will be," Johnson said.

"The request was for more information on a fraction of the overall submission. We will be working with our engineering consultant to provide a response to ensure that this important flood mitigation project is built and protecting Calgarians as soon as possible."

Once an acceptable assessment is submitted, Boss said the CEAA has up to 365 working days to complete its work.

The regulator would make a recommendation but the final decision to approve or deny the project rests with the federal environment minister.

With files from CBC's The Homestretch