In partnership with El Dorado County and Texas Southern University, the Tahoe Resource Conservation District (Tahoe RCD) is monitoring stormwater runoff from Elk’s Club Drive to quantify the amount of fine sediment that comes from the road itself. Samples are taken of the runoff water and sent to the laboratory for source apportionment analysis. This lab test uses molecular markers to determine what portion of the fine sediment in the runoff comes from native soil (road shoulder erosion), traction abrasives (road sand), and asphalt (the road itself).
Currently, Elk’s Club Drive is in poor condition. It is covered in cracks and potholes. Not only is a degraded road bad for public safety, it is difficult to recover road sand and other material through road sweeping. Road sediment is a large portion of the fine sediment that ends up in Lake Tahoe, reducing its famed clarity. Early results show that up to 30% of this fine sediment includes asphalt (aggregate and binder). El Dorado County will be repaving Elk’s Club Drive this summer. After it is repaved, the Tahoe RCD will continue to monitor the runoff from the road for an additional year. If data shows that repaving roads contributes to improved water quality (less sediment), then improved pavement condition could be recognized as a water quality Best Management Practice (BMP). This would not only be identified for garnering credits for the Lake Tahoe TMDL Clarity Crediting Program (https://clarity.laketahoeinfo.org/), but also potentially opening up water quality improvement funds for road maintenance. New roads would be beneficial for public safety, vehicle maintenance costs, aesthetic appeal, driving pleasure, road maintenance and sweeping operations, long term durability, snow removal operations, stormwater quality, and lake clarity.
A washoff simulation was conducted in April to analyze runoff under controlled conditions. Over 5,000 gallons of water were released on Elk’s Club Drive and sampled at the terminal location. In a rainstorm, water runs off the road shoulder contributing native soil in runoff. In a snowstorm, there is likely to be high concentrations of road sand on the road and in runoff. The controlled simulation excluded native soil and road sand from the procedure, and focused runoff on the road surface only. Early results show peak turbidities (cloudiness) occurring with peak flows, indicating that sediment is being continually supplied by the road and suggesting that the road itself is eroding. The sediment in the samples will be subjected to the source apportionment analysis to confirm if this hypothesis is correct. Though the data is not yet in, the Tahoe RCD and El Dorado County are hopeful that, in the future, investments in new roads will be viewed as a win-win for the community and the lake.
The Tahoe RCD, along with agency partners, is developing a Stormwater Resource Plan (SRP). The SRP is required by the California State Water Resources Control Board to establish eligibility for bond funding for stormwater quality improvement projects. It quantifies the multiple benefits of planned stormwater projects and prioritizes them for funding.
Tahoe RCD is hosting two public meetings to introduce the concept of an SRP, present highlights of the draft SRP, and allow an opportunity for public participation.
The meetings will be held at the following times and locations:
December 6th, 2017 at 4 pm – City of South Lake Tahoe Council Chamber
December 7th, 2017 at 9 am – Town of Truckee East Wing Conference Room
The Tahoe Resource Conservation District (Tahoe RCD) is pleased to announce the launch of a new interactive Monitoring Dashboard on Tahoe Regional Planning Agency’s (TRPA) Lake Tahoe (LT) Info website. This pubic-facing portal allows users to browse stormwater monitoring sites and displays summarized stormwater runoff data from around the Tahoe Basin. Sitka Technology Group out of Portland, Oregon is the principal developer of LT Info.
The intent of LT Info is to improve and streamline environmental and community decision-making and build public awareness of environmental and socio-economic conditions in the Lake Tahoe Basin. The first phase of LT Info development included the Environmental Improvement Program Tracker, the Parcel Tracker, and the Sustainability Dashboard. As the LT Info website matured with the refinement of these original applications, more environmental managers were excited to showcase their programs on LT Info.
The next application to be developed was Stormwater Tools, which allows local jurisdictions to report on their progress towards meeting Total Maximum Daily Load credits. The inclusion of Stormwater Tools prompted Andrea Buxton, Stormwater Program Manager at the Tahoe RCD, to contact the TRPA to be included in the development of the website. Tahoe RCD, in collaboration with local jurisdictions, scientists, and stormwater regulators, developed the Lake Tahoe Regional Stormwater Monitoring Program (RSWMP). RSWMP collects stormwater runoff data at eleven long-term monitoring stations around Lake Tahoe. The objective is to be able to measure improvement in stormwater quality over time as more environmental improvement projects are implemented in urban areas.
“The LT Info platform provided the ideal opportunity for us to showcase the results of the stormwater runoff monitoring we have been doing over the last four years. We want RSWMP data to be easily accessible to the local jurisdictions, the regulators, and the general public so that the positive effects of all the time and money spent on environmental improvement can be recognized” says Buxton.
By linking LT Info directly to the recently completed RSWMP Data Management System, developed by Geosyntec Consultants in Portland, Oregon and the Desert Research Institute in Reno, Nevada, with a seamless system-to-system connection, LT Info became a platform to display complicated stormwater monitoring data in easy to interpret formats for everyone from stormwater program managers,to regulators, project funders, and the general public, to use for their unique and individual purposes.
RSWMP is the first monitoring program to be incorporated into the Monitoring Dashboard. The TRPA is anticipating that the Monitoring Dashboard will include many other monitoring programs in the future. This will deepen the integration of various environmental monitoring and tracking programs around the Lake Tahoe Basin and increase the value of the data for decision makers.
“We are really excited about how much potential the Monitoring Dashboard has to connect actions to outcomes through the platform” says Jeanne McNamara, LT Info Platform Coordinator at the TRPA.
Please visit https://monitoring.laketahoeinfo.org/RSWMP to browse the beautiful displays and gain a better understanding of what managers are doing to work toward achieving Lake Clarity goals.
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.
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