Just days after the Army Corps of Engineers closed the recreation area of Abiquiú Lake after finding the presence of a blue-green algae bloom, parts of the lake were reopened Thursday.

Both the land areas and boat ramp are open, but swimming is still prohibited, dependent upon the results of more water tests, the Corps said.

Rangers patrolling the 4,000-acre lake, about 55 miles northwest of Santa Fe, found a suspicious-looking green coloring in the lake Aug. 8 that turned out to be blue-green algae, which can contain toxins.

Those blooms, if they carry cyanobacteria, can cause health problems for humans and animals if ingested, inhaled or touched. Skin exposure, for instance, can lead to rashes, hives and blisters. Swallowing the water can lead to stomach pains, vomiting and diarrhea.

Operations Project Manager John Mueller of the Abiquiú Dam Project said Tuesday that biologists ran tests on the blue-green algae blooms. The results of one sample, which came in late Wednesday, showed some concentration of cyanobacteria — enough to call for an “advisory level for public usage,” he said in an email.

“This is still an elevated risk for adverse health effects, so we are opening the public access of the reservoir for boating [and] fishing but restricting swimming … where the bloom is most prevalent,” he said.

Maddy Hayden, public information officer for the New Mexico Environment Department, said earlier this week the department often receives calls on algae this time of year. She said the department is not aware of any other lakes or bodies of water in the state reporting  blue-green algae blooms.

The blooms, which can grow in fresh or marine water, are the result of a number of factors including the amount of sunlight, high temperatures, low water levels and the impact of pollutants in runoff water.

The Environmental Working Group, a nonprofit activism organization in Washington, D.C., released a report last week saying blue-green algae is found in hundreds of lakes, rivers and other water bodies around the country, but authorities do little to notify the public about them.

The report says not all blue-green algae blooms are toxic.

The Corps has posted signs around the lake to inform the public that swimming is not allowed until further notice.

General Assignment Reporter

Robert Nott has covered education and youth issues for the Santa Fe New Mexican. He is assigned to The New Mexican's city desk where he covers a general assignment beat.