Thank you to Earl Conway for this update from Cochiti Lake, New Mexico, and many thanks to Sun Country Outdoors for their work as a Friends group!
Cochiti Lake Habitat Restoration
This project at Cochiti Lake, New Mexico addresses impairments from sedimentation, hazardous algae blooms, aquatic invasive species and initial vegetation removal and earth scouring during dam construction. The project is primarily funded by a Federal NFHP grant, and several small grants and donations from corporations, non-profits and individuals. The project is managed by Sun Country Outdoors, a chapter of Friends of Reservoirs. The primary objectives of the project are propagation of native aquatic and shoreline vegetation and fish habitat placement with an emphasis on spawning enhancement. The fish habitat deployment and planting is scheduled to be completed during 2023 with final adjustments and monitoring completed by September 31, 2024.
Slow but steady progress has been made on the project objectives.
- Improve and revitalize degraded aquatic habitat and enhance local aquatic communities through aquatic invasive species removal.Status: The project received unexpected help from nature with an abnormally high spring runoff. Cochiti Lake levels rose by approximately 25 feet in June. Two short surveys of the lake, one during the high water and one after stabilization in July were conducted to better understand the upriver seeds source and the effect of inundation. It appears that the Eurasian watermilfoil was severely reduced or eliminated. The water fluctuation also “washed” the shoreline gravel and initiated a resurgence of cottonwood/poplar seedlings. It appears the non-native white clover was killed. It also appears that cattails and some bulrushes were killed. However, surveys indicate that spike rush, smartweed, some sedges and Goodding’s willows are thriving in isolated coves and upstream. Coyote willows are flourishing and now dominate the shoreline in most of the coves to the extent they will limit angler access without some management.
- Improve aquatic habitat by stabilizing eroded shorelines and improving bank shading through planting live stakes, and native vegetation establishment and management.Status: Again, the project benefited from the high lake levels. The survival of the coyote and Goodding’s willows and the resurgence of cottonwood seedlings will provide additional shoreline shade. Many of the planted cottonwoods did not survive and they should be replaced with Goodding’s willows. A modest number of Goodding’s willow stakes and several rooted trees are ready to be planted in a survivability test near the west parking lot and in the upper end of the project area. A visit was made to a local aquatic and riparian plant supplier in July to determine availability of commercial plants for initial plantings. Several floating island designs have been reviewed to provide volunteers the opportunity to build floating seed sources for both aquatic and riparian native plants. A work day is scheduled in September to build, plant and deploy the initial floating islands. A greenhouse is also being constructed to provide future plant propagation and educational opportunities at the project office. The build is on a temporary hold to verify construction methods and obtain some missing components. A short meeting with the Cochiti Middle School staff also indicated they are looking forward to working on the project in their greenhouse.
- Create spawning and viable fish habitat by deploying fish habitat structures adjacent to restoration sites.Status: Several meetings were held to discuss different options for gathering input on the project and completing the required processes required to eventually obtained Section 401 and 404 water quality and fill permits. It was decided that the “408” process was the best path and New Mexico Bass Nation has submitted a formal request to begin that process. A Project Initiation Notice has also been created to detail the project. The project is under evaluation at the Albuquerque office. Prototype spawning habitats have been built for all prey-base species and spawning benches have been selected for black bass spawning structures. About 60% of the materials have been obtained for the fish habitat builds.
- Increasing the availability of prey-base fish.Status: Prototype and proven spawning habitats have been built or selected based on site surveys and projected water levels for the next five years. Habitat deployment will be planned for no significant increase in the lake level. This is the most significant assumption for the project. Several discussions were held over this topic before making a decision on what elevation to place spawning structures.
- Increase angler use of fish habitat sites (boat and shoreline anglers).Status: Several informal “creel surveys” were conducted to gather input from both shoreline and boat anglers to determine what type of fish attractors might work best. It was determined that about ten “dock hangers” will enhance the fishing dock. Angler-friendly artificial bushes will be used near heavy shoreline access points on the west side. With the closure of the east side, that area will be deferred until the end of the project, possibly being completed in 2024. A variety of structures will be used where boat anglers fish for pike and black bass as originally proposed in identified coves.
- Increase angler/user knowledge about the value and benefit of a healthy reservoir ecosystem.Status: During informal “creel surveys” there was an opportunity to communicate with local, regular anglers and gather input on the project while educating them on the role of fish habitat on the ecosystem. Youth education and involvement has already begun. The “Canoemobile” event hosted approximately 250 kids. They were provided short educational sessions on fishing, fish habitat, macroinvertebrates and sustainability. More volunteer and youth events are planned. The Cochiti middle school is aware of the project and planning to support the project with their greenhouse and students.
Supplemental Method Details:
A greenhouse with dimensions 32x36x12 will be constructed at SPA’s Cochiti Lake Project Office to provide adequate culturing facilities and mature transplants for founder colonies. A combination of outplantings of containerized plants and seeding will be implemented on multiple shorelines covering approximately 3.37 miles in length. Founder colonies will be installed at depths suitable for establishment (<3-ft) and will serve to provide immediate habitat and propagules for spread and recruitment in other suitable areas of the lake.
Species for restoration of native and desirable submersed aquatic vegetation include those able to withstand expected obstacles such as variable hydrology and herbivory. Submersed species selected are Illinois pondweed (Potamogeton illinoensis), longleaf pondweed, sago pondweed, Canada waterweed (Elodea canadensis), American eelgrass (Vallisneria americana) and coon's tail (Ceratophyllum demersum). Emergent species selected are smartweed, bulrushes and spikerushes.
Spawning habitat for largemouth and smallmouth bass impairments will be addressed by constructing and installing 200 custom plastic fish habitat structures, 40 “barrel” structures, and 14 tile pipe structures at selected restoration sites. About 200 custom designed spawning benches, "bushes" and artificial eel grass plots will be constructed and deployed near the construction scar. Original plans to install habitat on the sediment thalweg have been eliminated based on input from the Cochiti Pueblo. Disturbance of sediments will be avoided whenever possible.
Project success will be measured primarily by the reduction in the invasive aquatic species Eurasian water milfoil, the survival and growth of native vegetation plantings and live stakes, fish use of habitat structures at restoration sites (e.g., increased largemouth bass catch rate in NMDGF samples and by anglers), and the measured reproductive success of prey-base fish.
Survival and growth of native aquatic vegetation and woody vegetation plantings will be monitored through biannual and post flood photo point surveys of the restoration sites. A professional photographer was taken on the lake to document the high-water stage.
The project addresses climate change impacts by providing resiliency to the reservoir system during periods of severe drought and flooding. The 2023 spring runoff was more than average and came sooner and faster than in the past. The lake was constructed for sediment and flood control, so releases were limited, and the lake rose over 25 feet in two weeks. This has led to re-evaluation of some project features until the effects are better understood. For example, preliminary surveys indicate that the Eurasian watermilfoil has nearly been eliminated by the extra depth and turbid water during the early growing period. The flooding of the shoreline areas has also eliminated non-native white clover and started a rapid emergence of cottonwood tree seedlings. This should help with shoreline shading. Eventually the lake elevation will have to be increased to provide the authorized 50,000-acre feet recreational pool as sedimentation continues at a higher rate due to wildfires and burn scars.
Summary: In general, the project is progressing well, and the unexpected high runoff has provided the opportunity and time to fine tune project methods to provide better sustainability and to accommodate feedback from the Cochiti Pueblo, anglers and the project office. There are no urgent issues, but progress needs to be sustained on obtaining the fill permit.