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The standard was adopted in 2024, renewing the regional partnership’s long-term commitment to restoring the resilience of Stream Environment Zones (SEZ) by establishing a new restoration target. Protecting and restoring meadows and wetlands has long been a priority in the Tahoe Region to preserve wildlife habitat, maintain the natural functions of the ecosystem, and build the region’s resilience to climate change. Nearly forty-five years ago the Region established a goal of restoring 1,100 acres of SEZ. At the time the new standard was adopted, the Region had restored 1,775 acres (including 680 acres of SEZ restoration by USDA Forest Service between 1984-1987), enhanced 379 acres, and has acquired and protected over 900 acres.
Angora creek
The chart shows the Regional SEZ Quality for 2020 and 2023. SEZ Quality is an area-weighted average representing the SEZ condition index scores in the region. The SEZ quality is the sum of all SEZ condition index scores per SEZ Assessment Unit divided by the total SEZ acres in the basin.
Data provided by Tahoe Regional Planning Agency. Access detailed datasets on Tahoe Open Data, including: Stream Environment Zone Locations and Stream Environment Zone Data.
- Status
- Somewhat Worse Than Target
- Trend
- Insufficient Data to Determine Trend
- Confidence
- Moderate
- In 2024, the Tahoe Region established a goal of increasing the regional SEZ quality to 88 percent. During the assessment period, the average SEZ quality was 76.5 percent.
- Monitoring for this indicator follows the Lake Tahoe Stream Environment Zone Baseline Condition Assessment funded by a US EPA development grant and developed with our partner agencies. The stream environment zone (SEZ) condition index integrates size and condition to provide a single integrated value to assess wetland and meadow health in Tahoe.
- Between 2020 and 2023, EIP partners restored 37.9 acres of meadow and wetland and enhanced 268 acres.
- Detailed information on the status of Tahoe’s SEZ’s is available on the Tahoe SEZ Viewer.
Stream environment zones in the Tahoe Region and their rating. "A" rating is excellent condition, "B" is good condition, "C" is moderately impaired condition, and "D" is degraded condition.
The term "stream environmental zone" (SEZ), is unique to the Tahoe Basin, and is defined as: “Generally an area that owes its biological and physical characteristics to the presence of surface or groundwater." This definition includes perennial, intermittent, and ephemeral streams; wet meadows, marshes, and other wetlands; riparian areas, beaches, and other areas expressing the presence or influence of surface or groundwater. Enhancing the function of SEZs provides a range of critical ecological functions and ecosystem services. Foremost among the many functions they provide are maintaining water quality, allowing groundwater infiltration, trapping sediments, serving as hotspots of biological activity and biodiversity, and playing a critical role in the cycling of carbon and nutrients.
The SEZ restoration threshold was adopted in 2024. The peer review of the 2015 Threshold Evaluation highlighted the shortcoming of 40 years of tracking only the area of SEZ restored in the region; “In summary, the present approach to evaluating the condition and the improvement in SEZs is an overly blunt instrument with no apparent scientific basis beyond “more is better” (Hall et al. 2016).” In addition, the current standards contain multiple undefined terms and lack an accepted baseline against which the standard can be assessed. To address these issues, partners developed the SEZ condition index which integrates size and condition, to provide a single integrated value to assess SEZ in Tahoe. In 2020 partners completed the baseline assessment, compiling condition assessments for 98 percent of the meadows, marshes, wetlands, and fens in the region. That assessment is used as the baseline to establish the new target.
Disturbance and degradation of SEZs in the Tahoe Region began in the 1800s through logging, grazing, stream and river channelization, development, damming, fire suppression, and other activities, with environmental consequences that are still evident today. Higher temperatures and altered precipitation regimes as a result of climate change (Coats et al., 2010) further threaten to alter the dynamics of SEZs in the Tahoe Basin. In the most recent assessment wildfires drove declines in the SEZ condition.
EIP Action Priorities
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Restore Priority Meadows, Wetlands, and Lake Tahoe Tributaries
EIP partners are working together to restore several high priority watersheds in the Basin that provide valuable ecosystem services and improve Lake Tahoe’s clarity and water quality.
EIP Indicators
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Acres of SEZ Restored or Enhanced
Environmental Improvement Program tracking of projects enhancing the function of SEZ.
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Linear Feet of Stream Channel Restored or Enhanced
Environmental Improvement Program tracking of projects enhancing function of SEZ through in-channel work.
Example EIP Projects
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Incline Lake Property Planning & Implementation
Project includes removal of Incline Lake Dam structures, restoration of stream and meadow, and installation of permanent BMPs.
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Post-Caldor Fire Stream Aggradation using Beaver Dam Analogues: Saxon and Trout Creeks
Stream restoration project capturing the excess sediment caused by erosion from the Caldor Fire to raise an incised channel.
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Upper Truckee River and Marsh Restoration
Large scale wetland restoration project in the Upper Truckee River marsh.
Monitoring Programs
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SEZ Basin-wide Monitoring and Assessment Plan
The SEZ Basin-wide Monitoring and Assessment Plan provides details on the indicators and methods used to assess SEZ.
- Somewhat Worse Than Target. The regional SEZ quality decreased from 79 percent in 2020 to 76 percent in 2023. The threshold standard is to enhance the quality and function of meadows and wetlands from 79 percent to a minimum of 88 percent of the regional possible SEZ quality. Currently the SEZ quality is at 86 percent of target therefore, the status is somewhat worse than target.
- Insufficient data to determine trend. The scoring protocol was first used to establish a baseline score in 2020, and 2023 is the second iteration of the assessment. While scores declined slightly between 2020 and 2023, it would be premature to suggest that the decline suggests a downward trend in regional SEZ health. The largest three factors contributing to the decline were biotic integrity (29 percent), bank stability (27 percent), and invasive species (26 percent). The vast majority of SEZ (82 percent) in the Tahoe Region were found to have little or no change, 17 percent declined, and improvements were observed on 1 percent of SEZ area regionwide. The change in invasive species scores was driven primarily by updates to the “Priority Invasive Weeds of the Lake Tahoe Basin” list by Lake Tahoe Basin Weed Coordinating Group in 2023. The modifications included adding new invasive species and reclassifying priority levels of existing ones. The Caldor Fire likely had an influence on biotic integrity scores, and the big winters of 2021/2022 and 2022/2023 likely increased scour and erosion.
- Moderate. The monitoring protocol for wetlands and meadows was established with a technical advisory committee with an EPA grant using the best available data. The updated standard was adopted in 2024 and established a long term restoration goal, that is expected to take 20 years to achieve.
- N/A. Insufficient data to determine trend.
- Moderate.
No photos available.
- Uploaded On
- 7/31/2024
- File Type
- Description
- The Stream Environment Zone (SEZ) baseline condition assessment compiles information from a variety of sources to provide a comprehensive assessment of the health of SEZ in the Tahoe Basin. The assessment was completed in 2020.