A $43.1 million, decade-long storm-water filtration system and community infrastructure improvement project is nearing completion.

Caltrans project engineer Tarek Tabshouri said two Delaware sand filters and a series of basin catchers along U.S. Highway 50 are now functional, and bicycle trails, landscaping, Americans with Disabilities Act-compliant features and pedestrian lighting are expected to be completed soon.

Tabshouri said the sand filters are an excellent system for removing impairment, such as particulates, phosphorus and more.

“It’s not brand-new technology, but definitely new to the lake,” Tabshouri said.

The drainage inlets along the highway were implemented at historically high-volume areas where storm water collects and potentially washes into Lake Tahoe, Tabshouri said.

Before the implementation of the drainage system, Tabshouri said the water would end up in culverts with the particulates and other impairments, which reduces clarity within the lake.

“The project has a lot of scope,” Tabshouri said. “There are features we’ve never put around the lake before. There’s more to this project than just water quality.”

Tahoe Regional Planning Agency partnership and communications officer Kristi Boosman and TRPA environmental specialist Ian Judge have been intricately involved with the project and its completion.

Judge said water-quality monitoring will be conducted thoroughly to assess the system for the next two years, but the storm water will always be monitored. Monitors are currently being installed.

“The science tells us 72 percent of fine sediment is coming from the old infrastructure that do not have storm water filtration in place,” Boosman said. “These kinds of projects are showing the best clarity.”

The highways are the one biggest contributor of particulates and sediment within the lake, she said.

“Because of the lay of the land and topography, we need to customize the systems in those areas,” Boosman said.

A key component of the State of the Lake, the annual TRPA update on procedures and studies, is the “clarity challenge,” a standard of lake clarity the agency seeks. Boosman said. The agency aims to have 85 feet of visibility back in the lake by 2025. Boosman said in the clearest areas, the lake is at about 75 feet of clarity.

The multiple thresholds the TRPA addresses include the quality of water, air, fisheries, scenic area, recreation, noise reduction, wildlife and soil monitoring.

Judge said that the improvements also create a ripple effect of incentives toward business owners to participate in enhancing their locations and try to make more appeal to customers.

One Delaware filtration system is located near the Alta Mira Shopping Center and the other is located across from the El Dorado Public Library. The basins are primarily located around Lakeview Commons at the southernmost points of the lake. Construction started about three years ago by Disney Contractors.

The U.S. Highway 50 Trout Creek to Ski Run Boulevard project was a collaboration of South Lake Tahoe, Caltrans and TRPA with assistance from the California Environmental Protection Agency and the Lahontan Regional Water Quality Control Board, according to a Caltrans news release.