SEZ Baseline Condition Assessment
An assessment of the current conditions of Stream Environment Zones (SEZ) throughout the Lake Tahoe Basin
TRPA, in conjunction with partners in the Tahoe Basin, completed an assessment of current SEZ conditions in 2020. A total of 11,942 acres of meadows, wetlands, marshes, streams, and riparian areas were assessed. Ten indicators were used to assess overall SEZ condition and placed into four condition categories. SEZ fell into the following categories: "A" very healthy (49%), "B" healthy (23%), "C" moderately impaired (8%), "D" very degraded (17%), and 2% were incomplete assessments. This story map will tour SEZ throughout the Basin to highlight some of the findings of the assessment.
Development has greatly reduced the amount of SEZ in the Tahoe Basin. Use this map to scroll back and forth between historic satellite imagery (1940 for the South Shore; 1969 for the North Shore) and current satellite imagery to see how development has shaped the landscape.
History of Tahoe's SEZ: Development in meadows
Throughout the Tahoe Basin, development has occurred in historic meadows. Some meadows have been completely eliminated such as meadows and marshes at the Tahoe Keys. Other meadows are partially built upon with some of the historic meadow remaining, such as this meadow near the South Lake Tahoe airport. Overall, 1061 acres of historic meadow have been developed and no longer exist. Efforts are being made to remove development from some of these historic meadows through the Environmental Improvement Program (EIP).
History of Tahoe's SEZ: Development in riparian areas
In addition to historic meadows being developed, riparian areas in the Tahoe Basin have also suffered from past development. Overall, 270 acres of riparian areas have been developed and no longer exist. This is especially true around Incline Village where many riparian areas were heavily developed. Throughout Incline Village, streams were re-routed, ditched, and developed right up to their banks, such as this riparian area along Wood Creek. Today, many streams and their riparian areas have been restored through the EIP, but development in riparian zones remains common.
History of Tahoe's SEZ: Golf courses in meadows
Throughout the Lake Tahoe Basin, several golf courses have been built in historic meadows, with around 300 acres of golf courses existing in historic meadows. While critical functions are not totally lost like in systems that are covered in impervious surfaces, they are impaired. Efforts are being made to restore some of these historic meadows through the EIP.
History of Tahoe's SEZ: Grazing and other impacts to SEZ
While development resulted in the removal of many SEZ, SEZ that were not developed still suffered from other impacts such as grazing. One example of such a meadow lies to the east of the main Meiss Meadows complex. Despite being in a protected wilderness area, evidence of degradation abounds with headcuts and severe channel instability. Due to channel incision, the meadow no longer floods and there is soil cracking and sagebrush encroaching into the meadow.
Current SEZ conditions: Healthy SEZ
Healthy SEZ abound in the Lake Tahoe Basin. According to this assessment, 72% of SEZ in the Lake Tahoe Basin are functioning well (A and B categories), such as this meadow at the headwaters of Trout Creek, Hell Hole. Hell Hole is a mostly undisturbed site that is a good example of what a healthy meadow looks like.
Current SEZ conditions: Healthy SEZ - Third Creek meadows
At the headwaters of Third Creek there are numerous meadows providing a year-round supply of cold, clean water into Third Creek. These meadows are mostly very healthy and unimpacted, with one meadow at the former Incline Lake dam site slated to be restored.
Current SEZ conditions: Healthy SEZ - East Shore meadows
Much of the East Shore of Lake Tahoe is dry upland forest. However, some very healthy meadows are dotted throughout the East Shore, providing critical habitat along this portion of Lake Tahoe.
Current SEZ conditions: Healthy SEZ - Ward Creek
Despite some past disturbances in the Ward Creek watershed, through changes in land management actions and restoration projects, most of Ward Creek is now healthy and functioning well.
Current SEZ conditions: Healthy SEZ - Desolation Wilderness meadows
Desolation Wilderness contains dozens of meadows. As one would expect, these meadows are mostly highly functioning and healthy and represent some of the few untouched meadows in the Tahoe Basin. A few of the meadows are being encroached on by conifers.
Current SEZ conditions: Degraded SEZ
Due to past development and land-use actions, large amounts of SEZ are degraded or completely developed. 26% of SEZ assessed (3051 acres) were degraded, with most of the degradation around the South Shore, such as this site at the Upper Truckee Marsh. Projects through the EIP are planned to restore some of these degraded sites. More degraded SEZ will be highlighted at the end of the tour in the "Restoration Opportunities" section.
Current SEZ conditions: Using remote sensing to assess meadow health
This assessment used innovative remote sensing methods developed by the Desert Research Institute (DRI) to assess vegetation vigor in meadows. Satellite imagery obtained Normalized Differentiated Vegetation Index (NDVI) values from 1984 to 2019 for all meadows in the Tahoe Basin. NDVI is a measure of vegetation health, with higher NDVI values associated with more vigorous vegetation. Successful restoration projects like Cookhouse Meadow showed large increases in NDVI following restoration. Impacted meadows often show lower NDVI values and different overall trends than healthy meadows in the Basin.
Current impacts to SEZ: Conifer encroachment into meadows
Around 40% of meadows assessed had significant conifer encroachment (C or D rating). The complex of meadows surrounding Saxon Creek and Trout Creek suffers from extreme conifer encroachment. Large portions of the historic meadows are now encroached by conifers. Conifer encroachment was analyzed using a unique method where all conifers in meadows were mapped using LIDAR, increasing accuracy and greatly reducing the amount of staff time needed to assess this indicator.
Current impacts to SEZ: Channel incision
Many streams throughout the Tahoe Basin are incised. Incised channels are found both in developed as well as undeveloped areas such as this portion of Meiss Meadows. At this location, the channel was moved to accommodate grazing and became incised. This site, like many incised channels in the Basin, has formed a stable inset floodplain but the historic meadow is no longer frequently flooded. Historic grazing has led to channel incision at many sites. 30% of channels assessed for channel incision received a C or D rating.
Current impacts to SEZ: Headcuts
Headcuts are an indication of unstable systems and are found throughout the Tahoe Basin, with over 8% of SEZ assessed impacted by headcuts. This site near Sawmill Pond has been disturbed through the years with the building of Sawmill Pond, and areas upstream of the pond were cleared for development. While the development was stopped, the damage remains with multiple large headcuts dewatering large portions of the meadow.
Current impacts to SEZ: Streambank instability
Streambank instability in the Tahoe Basin has been greatly reduced over the last 30 years through projects and policies aimed at protecting watersheds. Areas of the most severe bank instability such as Third Creek and Blackwood Creek have been mostly fixed, but some areas of severe bank instability remain. An example of these unstable areas are portions of the lower end of Trout Creek which are degraded and suffer from excess bank instability. A large restoration project restored a section from Pioneer Trail to Black Bart Avenue, but the lower end of the restoration project is showing renewed signs of instability and degradation.
Current impacts to SEZ: Fish passage
Numerous culverts, bridges, and dams in the Tahoe Basin have been retrofitted over the last 30 years to allow fish and other aquatic organisms to pass through. Despite these efforts, many impassable culverts remain in streams, such as this culvert at Quail Creek. These culverts not only block passage, they also can cause instability by forcing streams through undersized culverts. Many projects are planned to allow for aquatic organism passage at culverts throughout the Tahoe Basin.
Current impacts to SEZ: Ditches and gullies
Ditches and gullies are present throughout the Lake Tahoe Basin from old development and agriculture practices. Ditches were commonly built to move water out of meadows to accommodate development or improve the meadow for grazing. Many of these ditches and gullies are still present and continue to negatively impact SEZ, such as the large ditches running through Bijou Meadow.
Current impacts to SEZ: Invasive plants
Terrestrial invasive plants continue to impact meadows throughout the Tahoe Basin. Plant species such as Bull Thistle, Canada Thistle, and Reed Canary Grass (as pictures here in a meadow in South Lake Tahoe) are found most commonly in meadows close to human impacts. While they are somewhat common, aggressive management by land managers have kept them from taking over most sites.
Current impacts to SEZ: Habitat fragmentation
Many projects over the last 30 years have focused on preventing further development in SEZ and removing past development from SEZ. Despite these efforts, development is still common in SEZ in the Tahoe Basin, such as this site in South Lake Tahoe where buildings, parking lots, ballfields, and roads are built in the historic meadow.
Restoration of Tahoe's SEZ: Blackwood Creek
Blackwood Creek was highly disturbed through road building, logging, and gravel mining in the watershed. Multiple restoration projects over the years have resulted in large improvements in stream health, with some additional restoration projects planned. Overall, 565 acres of restoration projects were assessed in the Tahoe Basin, with 507 acres appearing to be successful in the long term (A or B ratings).
Restoration of Tahoe's SEZ: Third Creek
Like many streams in the Incline Village area, lower Third Creek was once degraded with large amounts of unstable stream banks. Following a restoration project around 2010, lower Third Creek is now functioning well with greatly reduced streambank instability. This site is another example of a successful restoration project.
Restoration of Tahoe's SEZ: Angora meadows
There are numerous large meadows surrounding Angora Creek from its headwaters at Angora Peak to its confluence with the Upper Truckee River near Meyers. Many restoration projects have occurred on these meadows and most of these meadows are now highly functioning and healthy.
Restoration of Tahoe's SEZ: High Meadows
The High Meadows complex is a large group of meadows at the top of the Cold Creek watershed that was once heavily grazed. A large restoration project was completed in 2012 that was very successful. Some areas of meadow are still degraded in this complex and projects are planned to restore the remaining meadows.
Restoration of Tahoe's SEZ: Snow Creek wetlands
Portions of Snow Creek wetlands were slated for development in the 1960's and areas were cleared. The wetlands were saved from development and have since been restored, and are now functioning well.
Restoration of Tahoe's SEZ: Colony Inn meadows
This historic meadow was developed for a hotel in the 1970's. The hotel was removed and an attempted restoration of the site was completed in 2012. Significant resources have been invested in restoring degraded SEZ, but like ecological restoration projects around the world, not all projects in Tahoe are successful. This project was mostly unsuccessful with large ditches still dewatering most of the meadow and extremely dry, upland vegetation at the restored site. Changes in TRPA requirements for restoration projects have been made to ensure future projects are more successful. Overall, 58 acres out of 565 acres assessed on restoration projects were unsuccessful (C or D rating).
Restoration Opportunities: North Zephyr Creek
With over 3000 acres of SEZ still degraded or developed (final rating in the C or D categories), there are a plethora of SEZ restoration opportunities remaining in the Tahoe Basin. This next section will highlight some of the restoration opportunities. Some of these areas already have restoration projects planned for them, while others do not. These areas are just examples of restoration opportunities and do not represent all potential projects.
Most of the East Shore of Lake Tahoe is undeveloped with healthy streams. However, there are some exceptions. One of the most degraded streams on the East Shore is North Zephyr Creek. Portions of North Zephyr Creek are extremely incised and unstable with large bank failures.
Restoration Opportunities: Upper Truckee River
The Upper Truckee River, specifically the lower portion from Meyers to Lake Tahoe, is one of the most degraded systems in Lake Tahoe. Large amounts of meadow have been lost to development and degradation of remaining meadows such as headcuts, channel incision, and channel instability are still common. Several large-scale restoration projects have been completed, and many more projects are in the planning phases.
Restoration Opportunities: Benwood Meadows area
The upper meadow in the Benwood Meadows area is very degraded. Several headcuts, unstable streambanks, and an incised channel are leading areas of the meadow to dry out. Historic grazing is the likely cause of degradation at this site. This site is another good example of a degraded site far from the impacts of development.
Restoration Opportunities: Lake Forest meadows
The complex of meadows around Lake Forest have suffered from development and degradation over the years. Ballfields, marinas, buildings, and other development are now built in much of the historic meadows. Some of the meadows have since been restored but other areas are still developed and degraded.
Restoration Opportunities: Meeks Bay meadows and lagoon
Meeks Bay contains one of the largest meadow complexes in the Tahoe Basin. The meadow is extremely encroached on by conifers and the former lagoon has been converted into a marina. Multiple projects are planned to restore the marina to a lagoon and reduce conifer encroachment in the meadow.
Restoration Opportunities: Golden Bear meadows
This meadow is extremely degraded with over 10 headcuts, soil cracking, ditches, and sagebrush encroaching into the meadow. It was heavily grazed and cleared for development in the 1960's.