Low-Tech Process Based In-stream Structures
By Austin Heslinga, Farm Bill Biologist, KS
In recent years, the Great Plains have gone through drought and extreme weather events. These events have increased stream erosion, decreased forage pasture forage quality, decreased crop quality, and negatively impacted wildlife habitats. A way to mitigate the impacts of extreme weather events is the implement of PLAs and BDAs which can decrease the speed and store large amounts of water within the riverbed. In many western states, this EQIP approved practice has seen great success in mitigating large weather events and increasing stream quality. In the fall of 2022, Juniper Environmental began implementing their Low-Tech Process Based In-Stream structure project. This project was a collaborative conservation partnership included the United States Department of Agriculture (USDA), Juniper Environmental, Ducks Unlimited (DU), Kansas Department of Wildlife and Parks (KDWP), Pheasants Forever (PF), and many other conservation organizations.
Volunteers implementing a PAL structure in the bottom of a streambed, weaving Cedar branches, Locus branches, and Elm branches - this structure stretched the entire length of the stream channel.
The main objective of this project is to evaluate the effectiveness of Low-Tech Process Based (LTPB) complexes, such as Beaver Dam Analogs (BDAs) and Post Assisted Log structures (PALs), in the Great Plains’ prairie streams. This practice has not been approved to use in EQIP contracts in Kansas. However, Colorado and Utah have seen success implementing these structures and are approved EQIP practices. By conducting a project to evaluate the effectiveness of these structures, it could allow for PALs and BDAs to be a future EQIP practice in the Great Plains. The four study sites are in varying physiographic regions of Kansas and Nebraska. Using a combination of field and laboratory methods, water quality variables will be measured three times during the growing season of each project year (2022-2025). In October 2022, with collaboration of conservation organization employees and many volunteers, 23 BDAs were implemented at Brzon Wildlife Area. This 320-acre wildlife area contains a variety of habitat including crop fields, native grass cover, and small woodlots. There is also a small temporal stream that’s a part of the Republican River watershed. This location was based upon the surrounding land cover, which is mostly rotational cropland with many producers utilizing irrigation pivots. This area typically has high flow erosion events, high nutrient load, and lower water quality. The BDAs and PALs were create using 4x4 posts, cedar branches, locus branches, and any other vegetative cover available. These structures were located throughout the stream channel and built in many varying locations within the stream. The 4x4 posts were pounded in the stream channel at varying angles and depths. The 4x4 posts serve as an anchor in the stream bed with vegetation placed over and woven through. This allows for the water to be slowed down and any upstream debris to be caught in the structures. Although BDAs and PALs are constructed the same, the only difference between a Beaver Dam Analogs (BDAs) and Post Assisted Log structures (PALs) is size. PAL structures are larger and span the entire width and depth of the stream channel. BDAs only incorporate the lower half of the stream channel and do not always span the entire length of the stream channel. However, PALs and BDAs have differing ecological impacts. PALs are designed and implemented to withstand the force of the flowing water and provide as an anchored structure. This will allow the additional accumulation of vegetation, increased ability to decrease water speed, and increase water retention capabilities. Conversely, BDAs are designed to move within the stream bed. This allows BDAs to be swept downstream in extreme weather events, provide temporary cover, and establish varying depths within the stream channel. By creating vary structures within the stream channel, it will allow for a variety of ecological benefits.
Volunteers implementing a BDA using 4x4 Cedar posts, weaving Cedar branches through the posts and gathering more materials for the structure - this structure did not stretch the entire length of the streambed.
The ecological benefits of this project extend beyond improving water quality. Just like authentic beaver dam structures, our man-made structures can transition woodland meadows and streams into wetland habitats, which therefore increases plant, insect, and animal biodiversity. These structures can also assist in storing water during drought, decreasing the risk of flood, and protect agricultural lands. Successful implementation of these structures can have a prominent positive effect on the wildlife and the resiliency of stream channels. Without conservation partners like the USDA Natural Resource Conservations Service, Juniper Environmental Pheasants Forever, Ducks Unlimited, and the many volunteers that support conservation, this project would have not been possible. This is just one fine example of multiple conservation groups, volunteers and community members getting together to implement a conservation project/program. It’s crucial that moving forward, we continue to have conservation groups and volunteers willing to establish and implement conservation projects.
Low-Tech Process-Based Restoration of Riverscapes