Unlike development on most of the nation's waterways, building a house on the St. Croix River is tricky business.

That's because the federally protected river has rules and laws to protect its natural look and prevent deterioration of water quality. Now a new "Landowner's Guide to the Lower St. Croix Riverway," available at city offices, addresses building restrictions within the riverway boundary.

"Everybody's saying this is long overdue," said Natalie Warren, who coordinated the project to acquaint landowners with the law before they invest money in building new structures or modifying old ones. She is employed by the St. Croix River Association through a three-year state grant to work with landowners, real estate developers and local governments on land-use regulations.

"We're hoping people will realize they can get what they want if they work with the right people," Warren said. "It helps the decisionmakers decide the full scope of the project."

Because local zoning ordinances sometimes can be more restrictive than riverway rules, the guide advises landowners to consult with city and township offices.

The 22-page color booklet addresses common riverway regulations, mapped generally within a quarter mile from the river's edge:

• Structures must be earth or summer vegetation tones, with dark roofs.

• Maximum height of new structures, and additions to existing structures, can't exceed 35 feet to ensure they won't be seen from the river. Different restrictions might apply for structures built before riverway regulations were adopted.

• Hard man-made surfaces that prevent water infiltration can't exceed 20 percent.

• Restrictions on lot sizes vary according to where they're situated. A minimum lot size in a rural district, above ordinary high water level, is 2.5 acres. In an urban district, it's 1 acre. In an urban district with public sewer and water, it's 20,000 square feet.

• Lot width requirements ensure privacy for landowners, promote vegetative growth, and provide a buffer for fire separation. In a rural district, the minimum width is 200 feet. In an urban district, it's 150 feet, and in an urban district with public sewer and water, it's 100 feet.

• Setbacks from the water's edge help preserve the scenic character of the riverway, protect landowners against river flooding, preserve water quality and provide habitat for wildlife. Setbacks range from 200 feet in rural districts to 100 feet in urban districts.

• Setbacks from bluffs — slopes greater than 12 percent — prevent damage to both the river's natural beauty and to structures.

The guide also encourages planting of native plants, rather than lawns, to absorb rainfall and prevent stormwater from running directly into the river. Rain gardens also help absorb runoff.

"It's a privilege living on the riverway but it becomes a big responsibility," said Jennifer Hutchins Farrell, Lakeland's city clerk. Having a booklet that "lays things out" helps city officials and landowners alike, she said.

Ron Moorse, city administrator in Afton, said he participated in planning the booklet and thinks it will head off costly problems such as hiring an architect before knowing land-use regulations.

"We all agreed we need to get these out to everybody," he said, before "trying to fight City Hall. It's a whole lot easier to work together."

The St. Croix is one of 208 federally designated wild and scenic rivers. The "federal zone" encompasses the entire St. Croix watershed north of Stillwater under National Park Service management.

South of Stillwater, where most riverfront development has occurred, the Minnesota Department of Natural Resources and its Wisconsin counterpart work with cities and townships to manage river regulations.