As beach crowds boom, sea levels rise and population steadily increases, a new piece of federal legislation aims to wrap the southern Los Angeles County coastline into a federally protected national park with the Santa Monica Mountains.

The bill, introduced by South Bay Democratic Reps. Ted Lieu and Maxine Waters, would initiate a sweeping, yearslong scientific study of the potential effects on residents, wildlife, public trails and access to beaches and other recreational areas if the southern Los Angeles County coast is added to the Santa Monica Mountains National Recreation Area.

The Ballona Wetlands in Playa del Rey would be included, along with beaches from Santa Monica to San Pedro.

The legislation comes at a time of increasing strain on public resources.

Los Angeles County beach visits jumped 43.6 percent from 2007 to 2015, according to attendance figures from the county Fire Department’s lifeguard division. Attendance has climbed from roughly 50 million a year to more than 70 million in the past five years, stretching safety resources as lifeguard rescues increased nearly 30 percent from 2007 to 2015.

“Whether it is conserving the Ballona Wetlands, preserving our beaches or creating more opportunities for recreation in our urban areas like Baldwin Hills and San Pedro, this bill is a first step toward making more federal resources available for our trails, beaches and open space,” Lieu said in a written statement.

“Expanding the Santa Monica National Recreation Area would make more scientific and infrastructure funds available, thereby addressing a shortage of resources to preserve open space for conservation and recreation in our community.”

The Santa Monica Mountains National Recreation Area, created in 1978, encompasses more than 150,000 acres of coastline from Pacific Palisades to Point Magu, and inland to the 101 Freeway. Lieu’s bill, HR 4871, was introduced to Congress in March and is being studied by the Subcommittee on Federal Lands.

A companion bill, touted by Democratic Rep. Adam Schiff, whose district includes Echo Park and Pasadena, also would extend the Santa Monica Mountains National Recreation Area eastward into the San Fernando Valley and Ventura County to encompass the Rim of the Valley Corridor out toward the Angeles National Forest.

The specific effects of such a massive expansion of federal oversight aren’t clear, but the bill’s language focuses on expanding public space and residents’ access to it, while protecting the environment and natural ecosystems. Both bills have received broad support from environmental coalitions, but several regulatory agencies want to know more about how they could impact property holders, safety issues and regulatory mandates.

“The county has not taken a position on (HR 4871) yet,” said Carol Baker, a spokeswoman for Los Angeles County Beaches and Harbors. “We’ve been told that it would provide tools and resources without mandates and restrictions. But what they are, specifically, is not yet clear. It’s too early to say.”

Tom Ford, executive director of the Santa Monica Bay preservation organization The Bay Foundation, cheered the legislation, saying it could create a more coordinated approach to protecting beaches and wetlands while also making them more accessible for visitors.

“The hope would be that additional funding would come to expand preservation, ongoing scientific work and enable existing recreational uses to be enhanced and protected,” Ford said. “I’d love to really get a better understanding of how we are using our coast. This study is a chance for us to gain more wisdom and enhance our efforts.”

Ford said there are gaping holes in existing scientific research on how ocean acidification and hypoxia from global warming trends are impacting Los Angeles waters. Researchers have documented that increasingly acidic waters caused shellfish to die in Oregon, but more studies are needed across the West Coast.

Meanwhile, urban planners are expecting sea-level rise to require elevated coastal buildings and structures because seas will likely go up from about 4 inches to 2 feet by 2050. Beach erosion, already a problem at Los Angeles County beaches, also will be a concern as well as flooding, experts said.

“We’re going to have to alter our beach activities or enhance them through sand dunes or hard engineering solutions like sea walls,” Ford said. “There are a lot of hard decisions that this study would support. Sea-level rise and ocean acidification are big issues.

“It’s not going to get cooler as climate change progresses and people are going to keep coming to the beach.”