Jump to main content or area navigation.

Contact EPA Pacific Southwest Water Division

Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

Watershed Priorities - Lake Tahoe, CA & NV

Lake Tahoe Basin
Lake Tahoe Basin
Photo courtesy of Tahoe Regional Planning Agency (TRPA).

Tools in Place

On this page:


Lake Tahoe's clarity is world renowned and well documented. The lake has experienced a decline in water clarity since the late 1960s. A plan to reverse this decline and restore deepwater clarity to historic levels—known as the Lake Tahoe Total Maximum Daily Load or TMDL—was adopted by the States of California and Nevada, and approved by the U.S. Environmental Protection Agency (EPA) on August 16, 2011. Prior to approving the TMDL EPA Region 9 consulted and coordinated with the Washoe Tribe of Nevada.

The TMDL's implementation plan guides restoration efforts for a number of sources of pollutants responsible for the clarity decline. The plan calls for fine sediment, phosphorus, and nitrogen pollutant load reduction projects to be implemented by state departments of transportation and local municipalities, land and stream resource management agencies, and air quality regulators.

The TMDL and its Implementation Plan resulted fromf a ten-year development effort funded by state and federal agencies. Both the scientific research and stakeholder input that underpin the final restoration plan are among the most advanced ever applied to a TMDL in the nearly 40-year history of the Clean Water Act.

The Lake Tahoe TMDL:

  • identified the relative contributions of fine sediment, phosphorus, and nitrogen inputs to Lake Tahoe from major pollutant sources;
  • calculated the load reductions needed from the four largest sources (urban and forest stormwater runoff, stream channel erosion, and atmospheric deposition) to achieve both the TMDL numeric and interim (Clarity Challenge) targets of 97.4 and 78 feet (29.7 and 24 meters) respectively; and
  • identified a strategy to achieve pollutant load reductions needed to restore lost clarity.

TMDL Links

Management Actions Taken

  • Establishment of the Clarity Challenge which is an interim goal to achieve 80 feet of clarity within 15-20 years and considers the opportunities for achievable load reductions in all source categories.
  • Development of a suite of urban stormwater tools including a hydrologic load reduction simulation model to aid in the development and selection of alternative project design scenarios, as well as rapid assessment methodologies to help jurisdictions determine the relative condition of stormwater assets and to prioritize and evaluate maintenance activities.
  • Development of protocols and methods facilitating the consistent estimation and tracking of progress toward achieving restoration goals.
  • Development of a TMDL Management System to incorporate new monitoring, scientific and research information and ensure continual improvement and adaptive management occurs throughout implementation of the Lake Tahoe TMDL.
    • Definition of EPA's multiple roles and functions in implementing the Lake Tahoe TMDL, including: collaboration, technical assistance, funding, permitting, enforcement and oversight.
      • Link to EPA's Roles
Lake Tahoe
Lake Tahoe Clarity Commitment | Enlarge

Recent Events

On August 19th, 2013, U.S. Senator Harry Reid (NV) hosted the 17th annual Lake Tahoe Summit at Sand Harbor State Park Exiting EPA (disclaimer) on the East Shore of Lake Tahoe (Tahoe Daily Tribune coverage Exiting EPA (disclaimer) ). Prominent legislators and officials in attendance included former Vice-President Al Gore, U.S. Senator Diane Feinstein (CA), California's Governor Jerry Brown, Nevada's Governor Brian Sandoval, Russian ambassador to the United States, ambassador Sergey Kislyak, and U.S. EPA Regional Administrator Jared Blumenfeld.

At this year's summit, former Vice-President Al Gore delivered the keynote speech linking his work on global warming to issues facing Lake Tahoe and other waterbodies worldwide.

Implementing the TMDL

The CA Water Board and NV DEP are the two state regulatory agencies that oversee implementation of this TMDL. These two agencies may enact policy and regulations based on the TMDL analysis and key scientific findings of the TMDL. Each agency uses its regulatory authority and non-regulatory programs (see funding section below) to ensure that the performance objectives specified in this TMDL are achieved.

Achieving the interim Clarity Challenge—load reductions expected to improve Secchi disk depth by nearly ten feet—necessitates substantial reductions from all source categories, particularly urban stormwater runoff. The Lake Tahoe TMDL has blazed new ground by developing a comprehensive method for estimating, tracking and reporting progress from on-the-ground pollution control activities. Urban stormwater jurisdictions are expected to prioritize and implement needed load reductions at the catchment or neighborhood scale, as well as to verify and obtain credit for these activities through the Lake Clarity Crediting Program. Tracking protocols and performance measures are in place or under development for the other source categories, facilitating the evaluation and assessment of progress toward meeting load reduction goals and enabling greater transparency and accountability for the expenditures of public monies.

The following is a representative list of practices and treatment options that responsible parties might use to meet the Clarity Challenge load reductions by 2026, and achieve the TMDL in 2076. Many of these practices are already in use by responsible parties, and an enhanced level of effort may contribute to reduced sediment and nutrient discharges to Lake Tahoe. In the future, technological advances may add other actions to this list. This list is not intended to be exclusive; implementing agencies may select other actions to achieve required load reductions. Please refer to the State's TMDL Section 11.3 for more discussion on implementing the TMDL.

  • Stabilize and re-vegetate road shoulders and eroding slopes
  • Implement an aggressive street sweeping program with high-efficiency street sweepers
  • Upgrade/enhance fertilizer/turf management practices to reduce nutrient application
  • Remove impervious coverage (increase infiltration)
  • Apply advanced deicing strategies (to reduce or eliminate abrasive application) Upgrade/increase/enhance infrastructure operation and maintenance
  • Redirect runoff for additional treatment
  • Install and maintain infiltration systems
  • Install and maintain detention basins
  • Install and maintain sand filters
  • Control retail fertilizer sales within the Basin
  • Recommend landscaping practices that reduce nutrient mobilization
  • Install and maintain wet basins / infiltration basins
  • Install and maintain constructed wetlands
  • Install and maintain media filters in stormwater vaults
  • Pump stormwater to more suitable treatment locations
  • Put gravel on unpaved roads and pave dirt roads at access points
  • Reduce residential wood burning with incentive programs
  • Mulch and revegetate ski runs
  • Decommission and re-contour existing roads and trails
  • Implement stream restoration project and reconnect floodplains

Environmental Improvement Program (EIP)

Tahoe Regional Planning Agency (TRPA) Exiting EPA (disclaimer) launched the EIP Exiting EPA (disclaimer) in an effort to better implement the Regional Plan and highlighted it at the Presidential Forum at Lake Tahoe in 1997. Recognizing that capital investments, research, and monitoring were essential components of the Regional Plan, the original EIP called for an investment of $908 million in capital projects and $58 million in research and monitoring. The EIP also identified hundreds of specific projects and programs to be undertaken by more than 50 funding partners, including federal, state, and local agencies and the private sector. The projects were focused on improving air, water, and scenic quality, forest health, fish and wildlife, and public access to the Lake and other recreation areas. The prime directive of the EIP was to move the Tahoe Basin closer to environmental threshold attainment.

Lake Clarity Crediting Program

Lake Clarity Crediting Program Handbook Exiting EPA (disclaimer)
TMDL & Stormwater Accounting Video Exiting EPA (disclaimer)

The Lake Clarity Crediting Program establishes the framework that connects on-the- ground actions to the goal of restoring Lake Tahoe clarity. It defines a comprehensive and consistent accounting system to track pollutant load reductions from urban stormwater using Lake Clarity Credits. The Crediting Program aligns policies with ongoing implementation in order to drive accountability and motivate effective action to improve Lake Tahoe clarity.

2013 Highlights

We commend the work of state and local partners in creating and maintaining momentum to protect and restore Lake Tahoe especially in the face of resource constraints. EPA continues to support these collaborative efforts to focus on cost effective solutions to improve Lake Tahoe water quality and provide more livable communities.

Some of the highlights of the past year include:

  • Mechanisms are now in place with local jurisdictions to reduce urban stormwater pollutant loadings, the most significant source.  The Lahontan Water Board updated its stormwater permit for Placer and El Dorado County and South Lake Tahoe, and NDEP signed Interlocal Agreements with Washoe and Douglas Counties, and the Nevada Department of Transportation.
  • The Tahoe Regional Planning Agency updated its Regional Plan in December 2012. The Plan now includes an up-to-date framework that incorporates the science-based approach to restoring Lake Tahoe’s clarity laid out in the Lake Tahoe Total Maximum Daily Load (TMDL). EPA approved the companion CWA Section 208 water quality management plan on June 13, 2013.
  • Most significantly, local communities and jurisdictions are carrying out on-the-ground projects by through-out the basin reducing pollutant loads and contributing to improved water clarity. 
  • EPA remains committed to providing technical and financial assistance in support of improved Lake Tahoe water quality. 
  • We are fortunate to be managing $2.8 million of remaining SNPLMA funding from BLM for projects that support achieving the clarity challenge.  These projects are developing tools to assist State and local jurisdictions:  
      • Stormwater Load Reduction Plans:  Counties and NDOT in Nevada are receiving assistance to identify cost-effective practices concerning road operations and maintenance, private property BMP implementation and upkeep, and potential stormwater quality improvement projects. 
      • Streamlined Reporting: We are working with the Lahontan Water Board and Nevada DEP to make it easier for jurisdictions to calculate and report fine sediment load reductions--and to incorporate the latest science into tools to prioritize load reduction efforts.
      • Watershed Strategies: We are assisting with the development of community-based watershed strategies by the Resource Conservation Districts in five watersheds to implement and maintain areawide BMPs.  This approach is expected to demonstrate decision tools for use at the neighborhood/catchment scale.
      • Public Accountability: Finally, we are developing an on-line, annual reporting system on overall EIP progress, as the Lake Tahoe Restoration Act would require.


Funding the restoration of Lake Tahoe has been expensive and will continue to be costly into the future. Much of the funding for capital improvement and watershed projects, and scientific research has been from the Southern Nevada Public Lands Management Act (SNPLMA) which provides for the disposal of public lands in Clark County and in 2003, created a special account of the revenue generated by land sales to restore Lake Tahoe. New allocations of SNPLMA funds expired with signature of the final round of funding ($34 M) in August 2011, bringing the total expenditure over eight rounds to $300M. For more information on the current round of projects being funded, visit the Tahoe Basin Management Unit at the U.S. Department of Agriculture, Forest Service web site.

Top of page

Pacific Southwest NewsroomPacific Southwest Programs Grants & FundingUS-Mexico Border Media CenterCareers About EPA Pacific SouthwestA-Z Index

Jump to main content.