July 6, 2022
San Luis Valley Ecosystem Council
By: Isabel Lisle, Communications Manager
What is a riparian zone? Why is it important?
It’s a beautiful sunny day in September as students from the Justice Heritage Academy in Antonito, CO splash through the Conejos River searching for crawfish.
They peer under rocks and common CO plants found along the river banks, such as coyote willow and cottonwood. It’s an area rich with aquatic wildlife habitat and perfect for a day of exploring this riparian zone. A riparian zone includes land that occurs along the edges of rivers, streams or lakes. The presence of water greatly shapes the soils and plant life in these areas. According to the National Park Service, “riparian zones in the southwestern United States make up less than two percent of the land area, but they support the highest density and abundance of plants and animals of any habitat type there” (National Park Service, 2021). The students learn that the plants along the riverbank help maintain water quality through removal of excess nutrients and sediment from surface runoff. In the San Luis Valley, a group called the Rio Grande Headwaters Restoration Project (RGHRP) works hard to protect these riparian zones to maintain river vitality, water quality, agricultural water use, and protect habitat for aquatic wildlife.
Rio Grande Headwaters Restoration Project
In fact, RGHRP recently completed the first phase of a project on the
Conejos River called the Conejos River Partnership Project, designed to rehabilitate irrigation infrastructure, enhance aquatic habitat, and restore riparian and wet meadow habitats. In a recent interview with Daniel Boyes, RGHRP Program Manager, he explains the goal of this project is to “improve agricultural irrigation infrastructure, including diversion dams and headgates, along the south branch of the Conejos River, to increase efficiency and reduce maintenance for water users while also improving fish passage and restoring riparian habitat'' (Boyes, 2022). The RGHRP partnered with agricultural water users, the Conejos Water Conservancy District, Colorado Division of Water Resources, Colorado Parks and Wildlife, and private landowners to develop a plan that would benefit agricultural water users, who rely upon surface water on a daily basis, in conjunction with riparian and aquatic wildlife habitat.
Issues with aging agricultural diversion structures
The project focused on three key aging agricultural diversion structures that functioned poorly for water users, created barriers to fish passage, and disrupted the river’s natural sediment transport
processes. Daniel mentions that these aging diversion dam structures in the
Conejos River were pinch points that formed fish barriers and became clogged with sediment and woody debris. This continuously blocked fish and limited aquatic habitat potential for multiple fish species, including the native Rio Grande chub and Rio Grande sucker. Both species are considered Species of Greatest Conservation Need by the New Mexico Department of Game and Fish (NMDGF) and Colorado Parks and Wildlife (CPW) (Turner Biodiversity, 2018). In addition, the buildup of sediment and woody debris demanded frequent maintenance by farmers and ranchers, introducing additional labor and costs to address.
Solution: Build new diversion structures
These leaky structures proved inefficient when diverting water through headgates during low streamflow conditions, making it difficult for farmers and ranchers to access their full decreed water rights. The new diversion structures are built with natural grouted rock that enables water users to divert their water rights at all flows, includes a fish passage area with lower water velocities, and allows for the transport of sediment and debris. In addition to replacing aging infrastructure, headgate automation is added, where needed, such that headgates automatically adjust to changes in streamflow and therefore provide predictable and accurate water diversions. More efficient and accurate delivery of water rights allows water managers to more efficiently administer water rights throughout the entire Conejos River system, which benefits all water users. By rebuilding these dam structures and replacing them with efficient new technologies, Daniel and his team are able to protect the fish and conserve water. Finally, stream banks near these diversion structures that were lacking healthy riparian vegetation and/or experiencing accelerated erosion were restored by re-sloping the banks and revegetating the area with native riparian species.
Positive impacts of new diversion structures
There are many benefits to enhancing agricultural infrastructure, riparian zones, and river health. Daniel explains that more efficient diversion systems and healthy riparian corridors benefits farmers and ranchers by reducing their maintenance costs. With improved bank stability and new infrastructure, irrigators cut down on time spent clearing sediment and debris from their diversion dams, because the new low-flow water channel pulls sediment through and past the diversions. The low-flow channels create plunge pools, which are also great for fish habitat and, together with the fish passage areas, provide aquatic wildlife corridors across rivers. This project in particular, says Daniel, has “connected a lot of the south branch of the Conejos River, and provided aquatic connectivity by removing barriers to fish habitat.”
Healthy riparian zones benefit wildlife as well as farmers
Daniel emphasizes the collective impact riparian restoration work has on river health and supporting the livelihoods of farmers and ranchers. The ecological function of a river holds value for multiple reasons, he says, because of the symbiotic relationship between wildlife and rural agricultural farming practices. “Healthy
riparian zones provide ecological services that benefit agricultural water users, like reduced erosion and improved water quality. Wet meadows irrigated by farmers and ranchers foster habitats for the Sandhill Cranes, White-faced Ibis, ducks, and other water birds that migrate to the Valley each year,” Daniel describes. In this way, the partnership between watershed groups and farmers is mutually beneficial. It’s increasingly important for nature based organizations aiming to protect and restore rivers, and farmers and ranchers, who depend on water and land resources for their living, to form active connections and understand one another’s needs and goals. These connections will support more of these kinds of multi-benefit restoration projects in the future. A lack of conversation and understanding between the agricultural community and restoration and conservation based organizations can only hurt both. By encouraging the health of our ecosystems, we are in turn encouraging the health of our economies and communities.
Through the improvement of agricultural irrigation infrastructure, the Conejos River Partnership Project opened up new aquatic wildlife corridors and increased water efficiency for agricultural water users. Riparian and aquatic habitat restoration projects such as these are critical to river function and aquatic ecosystems, as well as to water users in the San Luis Valley. As drought increases, and water becomes scarce, the Valley must prioritize the restoration of its river and riparian zones. The students who explored the Conejos River on that blue-bird sky day squealed with delight as they pulled up another crawfish from the depths of the river. As Valley residents, not only do we have a responsibility to the river, but perhaps also to the next generation, for ensuring that they have clean water, enough water, and chances to explore the wonderful wildlife that inhabits these refreshing streams, ponds, and riverbanks for many years to come.