In the News

State Road Departments Help Protect Water Quality While Keeping Roads Safe
date posted: January 5 2004

By John Cobourn, Water Resource Specialist;
Heather Segale, Environmental Education Coordinator; University of Nevada Cooperative Extension

Living in mountainous terrain at higher elevations requires special winter services, such as snow removal and road salting and sanding. These efforts by the California Department of Transportation (Caltrans) and the Nevada Department of Transportation (NDOT) are intended to prevent roadway accidents and make driving in the Sierras safer.

Both Caltrans and NDOT are working hard not only to keep the roads safe, but also to keep sand and salt from polluting Lake Tahoe. The sand that’s being used this winter at Lake Tahoe is very different from what was put on the roads just a few years ago. It’s a tougher rock called “spec D” sand, and it contains less phosphorus. “The sand doesn’t break down into very small powdery particles that would either fly up into the air causing an air quality problem or break down and go towards Lake Tahoe,” says Thor Dyson, NDOT district engineer.

Aside from the new sand, both Caltrans and NDOT are also using technology to help them keep Tahoe blue. “There are ten high-tech road weather stations on the Nevada side of the lake. They tell operators whether the roads are wet, dry, icy or snowy, and that information is used to determine just how much sand and salt gets put on the roads,” Dyson says. “Our total storm management program also includes sweeping and picking up sand off the roadway surface as well as collecting sand from the ditches and sediment trap basins.” As soon as the sun comes out and the roads start to dry, the sweepers are sent out. Removing the sand after each storm reduces the amount that will wash into storm drains that flow into the lake.

Since 1995, NDOT has played an active role in implementing state-of-the-art measures on its roadways to control erosion and protect water quality, helping to preserve the delicate environment of Lake Tahoe. NDOT’s goal is to minimize discharge of sediment and pollutants from state roadways to the lake. To date, NDOT has completed 11 roadway and environmental improvement projects. NDOT continues to plan and implement erosion control, water quality and drainage improvements on nearly all sections of its roads in the Tahoe Basin. By 2010, NDOT will spend approximately $100 million on erosion control and water quality improvements in the Tahoe Basin. These improvements include simple sediment traps, pretreatment vaults (sediment traps and sand-oil separators), and even sediment basins to deal with the runoff from road cuts and highway alignment structures.

Caltrans also has been working hard to protect water quality at Lake Tahoe. Caltrans is currently conducting research at its award-winning facility at Lake Tahoe to develop new storm-water treatment processes. Currently, infiltration is the only storm-water treatment process that can meet the stringent water quality standards in the Lake Tahoe Basin and, at the same time, function along our highways. Factors such as high ground water and unsuitable soil types can cause nature’s normal cleaning mechanism (infiltration) to be ineffective in certain locations, so the goal of this research is to identifiy new technologies that could be used in these situations.

One example of this kind of research is the alumina project. In 2003, Caltrans tested a new compound on Highway 50 near the airport to see if it could remove nutrients such as nitrogen and phosphorus from roadside storm water before the water flows to the lake. The compound, called alumina, is a combination of aluminum and oxygen. It looks like tiny white chips, and is about five times as expensive as road sand. If tests prove successful, this compound might be incorporated into more Caltrans storm-water projects in the basin.

By testing new technologies, using a different grade of sand, limiting the amount of sand that gets put on the roads, and taking it off immediately after a storm, NDOT and Caltrans have reduced the amount of roadway pollution they contribute to Lake Tahoe by as much as 75 percent in some instances. They are two more agencies that are pitching in to make a difference in the fate of Lake Tahoe.