SOUTH LAKE TAHOE, Calif. – July 17, 2017
Keeping roads in good condition in the Tahoe Basin has always been a struggle, especially when winters wreak havoc on the asphalt surface. While diligently removing snow so that we may all travel safely, heavy snow removal equipment, with large tires covered in hefty chains, chew up the surface of the road. Road sand, critical in keeping vehicles from sliding on icy roads, combined with normal vehicular traffic, also grind and crush the pavement surface. The frequent freeze and thaw process contributes to asphalt cracking. Dodging pot holes is a requirement for driving safely in the Tahoe Basin. In turn, poor road conditions damage vehicles, increasing the cost of vehicle maintenance.
“Vehicle wear such as popped tires and worn shocks and struts are costs the public pays for inadvertently, and may be greater than or equal to the cost of investing in improving the road surface” says Russ Wigart, Stormwater Program Coordinator with El Dorado County.
It is obvious that poor road conditions lead to more dangerous driving and cycling conditions, unsightly roads, and more wear and tear on vehicles, and higher maintenance costs. However, there is a new reason to care about the condition of our roads — water quality. Degrading pavement contributes to an increase in fine sediment particle concentration in stormwater runoff. Fine sediment particles, or FSP, are the leading cause of lake clarity decline.
“When the pavement surface gets destroyed by heavy equipment, chains, and normal vehicular traffic, the degraded asphalt gradually gets ground into smaller and smaller particles, resulting in very small sediment particles. When these tiny particles get into Lake Tahoe via stormwater runoff, they stay suspended in the water column because gravity is not strong enough to settle them to the bottom. This makes the lake look cloudy” says Andrea Buxton, Stormwater Program Manager at the Tahoe Resource Conservation District.
A recent study, conducted by El Dorado County, UC Davis, and Texas Southern University, collected stormwater samples from two roads in South Lake Tahoe to identify the major sources of clarity reducing FSP in urban runoff. Molecular markers were used to calculate the fraction of FSP that came from each source. The major sources were road-side soil, pavement wear, and traction abrasives (road sand). There were no significant differences between the two sampling sites.
“The results of our study suggest that pavement wear is the second largest source of fine sediment in urban stormwater runoff and fine sediment directly affects Lake Tahoe’s clarity” says Wigart.
Depending on the time of year and type of precipitation the contribution of FSP to urban stormwater runoff from road-side soil ranged from 20%-70%, pavement wear ranged from 18%-53%, and traction abrasives ranged from 7%-21%.
Additionally, a smooth road in good condition is much easier to sweep. Road sweeping machines are much more effective at picking up the fine sediment that inevitably ends up on the road surface if that surface is not covered in cracks and potholes that retain sediment.
Asphalt mix design has come a long way in the last decade and is now engineered for better durability. Adding polymers to the mix increases surface elasticity, allowing the road surface to better resist temperature changes and wear and tear from tire chains and heavy equipment. This not only limits the production of FSP from the road surface, but reduces the cost of road upkeep as well. The City of South Lake Tahoe has been using polymer based asphalt for the last several years but it is estimated that less than ten miles of roads have been repaved with the new mix to date.
These findings imply that maintaining pavement in good condition could positively impact urban stormwater quality and ultimately lake clarity. El Dorado County and the Tahoe Resource Conservation District would like to continue investigating the relationship between high quality roads and reduced FSP in urban stormwater runoff.
“Our ultimate goal is to get good pavement condition recognized as a Best Management Practice (BMP) for improving urban stormwater quality in the Lake Tahoe Basin” says Buxton, “the results would be a win for the lake and a win for the public.”
“Combining better roads with responsible snow removal and sanding operations could be the future for improving driving experience, reducing vehicle wear, and improving lake clarity” says Wigart.
To stay up to date with the Lake Tahoe Regional Stormwater Monitoring Program please visit https://monitoring.laketahoeinfo.org/RSWMP.
So you think you know about AIS? Join us Wednesday June 28th at Moe’s in Tahoe City from 5 p.m. – 8 p.m for trivia, fun, prizes, food, and drinks.
Gain a leg up on the competition and a free drink ticket by joining us from 5 p.m. – 6 p.m.
Trivia will start promptly at 6 p.m.
For Facebook invite information click here
The early storm event that began on January 7 with over 5 inches of rain in some regions of the Lake Tahoe Basin before turning to snow, delivered a massive amount of runoff to the Lake in a short period of time. During this storm event the Tahoe RCD Stormwater Monitoring Program measured the highest flows ever recorded at all eight monitoring locations since monitoring began in 2013. Our Tahoe Valley site, located off Tahoe Keys Blvd, measured 1.5 million cubic feet of flow, nearly 90% of the flow that was observed throughout the whole 2016 water year!
The Tahoe RCD monitors urban stormwater runoff around the Lake Tahoe Basin, providing the science that helps guide stormwater managers in environmental improvement project design and informs them if projects and management strategies have been successful in reducing pollutant loading to Lake Tahoe. Each stormwater sample is analyzed for fine sediment particles (FSP), nitrogen, and phosphorus to estimate nutrient and sediment loading from urban stormwater runoff. This last storm produced over 18 million gallons of runoff just from the sites we monitor alone. All data collected throughout a “water year”, October to September, is compiled into an annual monitoring report, given to stormwater managers and posted on the Tahoe RCD website. With successful implementation of environmental improvement projects that promote infiltration of runoff before it gets discharged to the lake, we have had the pleasure of retiring two of our urban stormwater monitoring sites as we saw significant reductions in pollutant loading from these locations.
The Stormwater Monitoring Program is continuously looking for ways to improve stormwater monitoring efforts. New for the 2017 monitoring season, the majority of our sites were outfitted with remote monitoring equipment, allowing us to monitor these sites with smartphones. The new remotely accessible equipment effectively allows our team to view what is happening at our monitoring sites in real time, and determine the best way to manage each individual site during storm events. Our scientific monitoring team is deployed in the most inclement of weather, because good science doesn’t take a break. The severity of this recent storm brought downed trees, dangerous road conditions, and a wealth of water. However, with these remote monitoring systems in place, our team was able to monitor all of our sites without making extensive trips into the field from the safety and comfort of our homes. This new remote technology allows for more reliable data management and easier data reporting.
The Landscape Conservation Program is seeking input from past participants of the program in order to continue to serve the community with high quality services into the future.
If you have received services through the the Landscape Conservation Program in the past, we please ask that you take 5 minutes of your time to fill out the online survey at the link below.
Your feedback is highly valued and is integral to the continued development of the program. We thank all that participated this summer for for another great field season.
Come join and join us for a night of hands-on activities and presentations about the past, present, and future of aquatic invasive species control and prevention efforts.
This year’s annual public forum will be held from 5:30pm – 7:30pm at the Tahoe Center for Environmental Sciences in Incline Village which hosts a variety of hands on exhibits such as: an invasive species station filled with various invasive species and a timeline of introduction, including a fish tank displays with live native and invasive fish species. Step onto the boat exhibit and learn about the secchi disk and how it is used to describe Lake clarity, or take a tour of the hands-on information about Lake Tahoe and its history. Enjoy refreshments as you tour the interactive booths and learn about the numerous actions and ongoing Science that is being done to protect Lake Tahoe while the kids take part in an invasive scavenger hunt. Presentations will give participants information about Eyes on the Lake and invasive weed identification, control projects planned for 2016 and beyond, as well as a presentation from the Tahoe Keys Property Owners Association about their role in tackling invasive species (see schedule below).
6:00 – Welcome “Tahoe Keepers Video”
6:05 – “Eyes on the Lake” Invasive Weed Information
6:20 – Aquatic Invasive Species Control and Prevention Programs
6:35 – Tahoe Keys Invasive Weed Plan
For more information or to RSVP contact Sarah Bauwens 530-543-1501 ext.126 or email@example.com.
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