Surprise Lake Camp, one of the country’s oldest Jewish summer camps, told families on Monday that it would not be opening this year because of worries over the coronavirus.“Every medical professional we consulted said that for a camp that opens in this environment, it’s not a matter of if — it will be there,” said Bradley Solmsen, the executive director of the camp in Cold Spring, N.Y., about 55 miles north of New York City. “Even with testing, the likelihood of us having it if we opened was very, very high.”Surprise Lake joins many camps across the region and the country that have already decided to close this summer, even before some governors, including those in New York and New Jersey, have announced if they would be allowed to operate.But with summer camp a ritual for many children and a lifeline for working parents, other camps are still hoping that they will be able to welcome children.Directors believe they can keep campers and staff safe by taking steps like limiting the number of children, restricting interaction with outsiders, frequent disinfection and screening for the virus on arrival.“People want camp,” said Howard Salzberg, the director of Camp Modin in Maine, where the governor is allowing sleepaway camps to open. He said his phone had been ringing incessantly since he announced he would open for the season on July 9, and that nearly all his 300 regular families have committed to coming back.“Some have sent me notes saying, ‘We know it is a risk, but thank you for taking a risk for our children,’” he said.The inconsistent picture for summer camps highlights the difficulty parents and operators face when so much about the coronavirus is still unknown.The new coronavirus-related inflammatory syndrome recently discovered in children, though rare, adds to the concern, and Gov. Andrew M. Cuomo said Thursday that he needed more information about the sickness before making a decision on camps.New York City has already canceled its Parks Department camps, and the Fresh Air Fund, a nonprofit that sends low-income children to sleepaway camps outside the city, will not do so this year.Jill Kolano, a mother of two elementary school-aged children in Wayne, N.J, is still waiting to hear if a local Boys and Girls Club camp will be open, but probably won’t send her children even if it is.“I would want to know how they’re going to be cleaning and how they’re going to be distancing the kids,” she said. “I still wouldn’t really feel 100 percent comfortable.”In the New York region, Connecticut is allowing day camps to open in late June, but overnight camps must stay shuttered. In New Jersey, Gov. Philip D. Murphy said camps may be able to open with “limited in-person engagement” if public health conditions continue to improve.Some camp operators have already decided it is too risky to open even if they do get the green light.Lauren Rutkowski, the owner and director of Camp IHC in Wayne, Pa., said that after speaking with distributors of tests for the virus, the camp decided it could not rely on their accuracy. Tests can produce up to 30 percent false negatives and research on the testing of children is limited.And if the virus entered her sleepaway camp, she said, “you have to accept that it is pretty much going to spread like wildfire.”But other operators have been busy coming up with safety plans. Mark Transport, the owner of Crestwood Country Day Camp on Long Island, plans to close camp on rainy days to avoid crowded indoor spaces, stagger arrival times and conduct daily temperature checks for as many as 500 campers spread over 17 acres.“We are trying to restore a sense of normalcy for kids, so you have to think out of the box,” he said.Dr. David Cennimo, an infectious disease expert at Rutgers New Jersey Medical School, said keeping the virus out of camps would be challenging no matter what measures operators take.“I think if I ran a camp, I probably wouldn’t want to open,” he said. “But if you think that you could control the spread if your defenses were breached, and you have a plan to do that, you may be willing to try. You are asking people to trust that you have that plan.”Trust is a major factor for families considering sending their children to camp. Jeff Feig, of the Upper West Side, is planning to send all three of his sons to Camp Modin, which they have attended in past summers. He has faith in Mr. Salzberg, the camp’s director.“If anyone is on top of this, he is,” he said. “His approach is thoughtful, and he is aggressive about how he is planning to manage it.”Camp Modin’s operators plan to turn camp into a kind of “quarantine bubble.” Counselors will arrive early to quarantine and will be tested for the virus. Campers will be tested before their arrival and after they get to camp, which will have a bigger medical staff than usual.“For many of these kids,” Mr. Salzberg said, “camp is an essential part of their existence, and if we can give it to them, it has to be worth trying.”In some states that are further along in their reopening, including Connecticut, day camps have been deemed an essential child care service and can operate with restrictions.They are taking cues from federal reopening guidelines and a new guide from the American Camp Association that provides extensive recommendations, including cleaning sports equipment after each use and dividing campers into small groups with designated counselors that maintain social distance from other groups.Camp Riverbend in Warren, N.J., is hoping to host several hundred campers if permitted.“We have bought as much P.P.E. as we could find, foggers and disinfectants, hand sanitizer, and disposable gloves and face coverings for staff,” said Jill Breene Cheng, a camp director. “We are renting portable hand washing stations and portable water bottle refillers and amping up the cleaning and disinfecting.”Day camps pose an extra unknown in terms of risk because campers and staff return to their families each night where they could be exposed or spread the virus, said Dr. Jessica Justman, an epidemiologist and professor of medicine at Columbia University’s Irving Medical Center.“Will the amount of virus circulating in the community be low enough so that level of mixing will be OK, or will that trigger a second wave?” she said. For some families, the risk is worth it.“I’m going to send my kids to any and all camps that open,” said Kim Marcus, who lives in Woodbury, N.Y., and hopes her two daughters, ages 12 and 10, can still go to overnight camp, and her 7-year-old to day camp.Other parents, like Stacy Mooradian of Jersey City, said that they were relieved when their camps ultimately canceled. Her 8-year-old son’s two-week sports camp at New Jersey City University made the call a month ago, and his other camp at Liberty State Park canceled this week. Her 12-year-old son’s sleepaway camp is only operating remotely.“I can’t think of any other camp option, day or sleepaway, that would be able to satisfy the distancing and safety requirements the governor is recommending,” she said. “But I still need to figure out what to do with the kids.”Lauren Hard contributed reporting.