Lake Tahoe snowmelt floods water sampling labs, hydrologists with work

A web of agencies and scientists work day and night each spring to monitor the aquatic health of one of North America’s most majestic alpine lakes

In the world of water quality monitoring, there is perhaps no more majestic setting or no more intense industry epicenter than Lake Tahoe.

Twenty-two miles long, more than 1,500 feet deep — and surrounded by vacation homes, ski resorts, casinos and lodges — Tahoe is the perfect mix of jaw-dropping, crystalline natural treasure and highway- and home-ringed recreation Mecca that has fueled an intense, long-term web of water quality monitoring programs to gauge the lake’s aquatic health.

Over the span of more than 50 years, scientists have deployed all throughout the year, all across the lake, to gauge sediment loading, nutrient concentrations and water clarity.

But one time of year — when the mountains of snow that ring that lake begin to slowly succumb to the spring’s long days and warm sun — brings of a flood of water quality monitoring work to sampling labs, scientists, non-profit groups and regulators.

The few weeks when spring runoff intensifies — swelling streams and filling the lake with fresh snowmelt — is one of the most critical annual cycles for the clarity of the lake. It is then that agencies can gauge if BMPs (Best Management Practices) are filtering road grime and sediment from construction sites, driveways and roadways. It is then that the effects of the millions of dollars that are regularly invested in catch basins, filtration ponds, and stream and wetland restoration are calculated.

Hydrologists, volunteers and laboratories are flooded with work, literally working day and night to pinpoint the effect of stormwater drainage on one of the world’s most studied bodies of water.

“If [runoff peaks] at 12 o’ clock at night on Christmas day, you go out a monitor then because you don’t want to miss that. Often you are out there in the middle of the night or on weekends,” said John Reuter, associate director of U.C. Davis’s Tahoe Environmental Research Center.

While the waters of Lake Tahoe have been monitored since 1958, agencies have only recently been examining the precise effects of stormwater drainage on Lake Tahoe’s water quality. In 2003, in conjunction with the EPA-mandated Total Maximum Daily Load program, agencies began sampling 16 stormwater sites around the lake. The results confirmed that 70 percent of the fine particles that end up clouding Lake Tahoe’s clarity are coming from urban sites.

Lake Tahoe’s three pollutants of concern — Phosphorous, Nitrogen and fine sediment — are tested and gauged by agency and private labs in the region. Phosphorous and nitrogen stimulate algae growth in the lake, which clouds the lake’s clarity, and sediment that is five times less thick than a human hair, gets suspended in the water, also impairing Tahoe’s famed crystalline waters.

Laboratories like nearby Sparks, Nev.-based WETLAB brace for the flood of laboratory work that each spring runoff season brings.

WETLAB’s state-of-the-art lab was built in 2006 to accommodate the increasing monitoring workload of water analysis from nearby agencies, mining regulators and environmental non-profits. The lab’s business, built on all types of regulatory compliance and environmental restoration work — from Lake Tahoe water testing to environmental testing around mining sites — has boomed in the past year. WETLAB has grown revenue by nearly 30 percent in the last year and hired over 11 full- and part-time employees.

“WETLAB braces for spring each year, knowing that snowmelt means our busy season is here,” said Michelle Sherven, president of WETLAB. “We have even added services, like a dedicated shuttle between our lab and Lake Tahoe, to help busy agencies and non-profit complete important water tests on time during the tense runoff months.”

The precision of the water quality testing is incredibly important as the results guide heavy federal, state and local investment in the environmental future of the lake.

Some of the fixes to the stormwater pollutants that run off of roads, driveways and roofs are simple and common — street sweeping to catch sediment before it is washed into the lake or filtration basins. But when dealing with very fine sediment and minute particles that wash swiftly from shoreline urban areas into the lake, some unique, cutting-edge solutions to Lake Tahoe’s stormwater pollution are being considered, said Reuter.

Ideas like a “pump-and-treat” system — where stormwater is pumped uphill to a man-made filtration area or a natural watershed where the sediment can slowly filter out of the water before it reaches the lake — are being talked about.

Whatever direction the efforts to maintain and restore Lake Tahoe’s famed water clarity take, springtime will continue to be a critical season for scientists, regulators and laboratories to gauge the condition of one of the nation’s most treasured natural wonders.