ST. PAUL — Dakota County is carefully planning to build part of a 27-mile bike path in the Spring Lake Park Reserve near ancient American Indian burial mounds, but before it settles on an exact route, a state archaeologist will help identify the grounds to ensure they are not disturbed.

The Mississippi River Regional Trail will include a 6-mile stretch near burial mounds thought to be between 1,300 and 1,700 years old were found in the 1950s.

“We treasure those resources,” said Bruce Blair, manager of facility development for Dakota County. “Culturally, they’re very valuable. They’re priceless. We don’t want to do anything that could increase the opportunity for them to be damaged.”

The Minnesota Indian Affairs Council monitors nearly 1,000 burial mounds throughout the state. Its cultural director, Jim Jones Jr., said the trail should avoid the mounds and not highlight the artifacts. The state’s office of the state archaeologist will help the county identify boundaries for the mounds.

Parts of the trail exist already. Work on the segment near the mounds is expected to start in 2013, with the opening projected for 2015. Federal grants and local funds are paying for the estimated $4 million costs for the trail.

The park area has been studied for its archaeological significance from as far back as 1,000 B.C., said Ed Fleming, curator of archaeology at the Science Museum of Minnesota.

The mounds at Spring Lake Park Reserve aren’t very evident today, Blair said. One mound is 200 feet long. But the small slopes are overgrown by prairie grass and other foliage. To get to them, it’s a 45-minute hike one way, with no trails leading to them.

“They’re very subtle,” Blair said. “They’re almost flat. Nevertheless, they’re very real.”

The mounds are positioned on the southern side of Spring Lake.

There are more than 12,000 recorded American Indian burial mounds throughout Minnesota, said state archaeologist Scott Anfinson. He locates and defines boundaries for burial mounds as well as unrecorded cemeteries belonging to early settlers.

Mound building first started in the state in 500 B.C., Anfinson said. Native groups in the area continued the practice of mound building until about A.D. 1500.

The two known Spring Lake Park Reserve burial mounds, called the Bremer Mounds, were first discovered and partially excavated in the 1950s by the Science Museum of Minnesota, Fleming said.

Remains from at least 15 bodies were taken by the museum, Fleming said. The remains are now being studied and recorded at Hamline University, Fleming said. Officials will attempt to repatriate the remains, returning them to tribal groups they belong to, once the work is complete.

But determining who that is can be difficult.

Years ago, people who inhabited the area had different tribal affiliations than the American Indians tribes of today, but scientists say they were ancestors of today’s tribes, Fleming said. Remains at the Bremer Mounds might be ancestral or culturally affiliated with the Dakota and Ho-Chunk nations.