Current project description

Monroe creek flows into the Weiser River at Weiser and ultimately flows into the Snake river. Monroe Creek is a 25.4 mile long stream that has severe erosion in some parts. The stream has not had much work done on it and the erosion was threatening a home and several farm-ranch properties. We added bioengineering, rock barbs, willow plantings, riparian herbaceous cover, and fencing. These BMPs were applied to approximately 2,500 linear feet along several different properties on Monroe Creek. There is an average eroding bank height of twelve feet. Significantly less soil erosion and increased water quality is the benefits of stabilizing the banks along this stream. Sediment, nitrogen, and phosphorus will be reduced as a result. This project will be completed June of 2024

The Weiser Irrigation District , saw the need to resurface the Galloway Dam spillway. We realize the structure has needed repair for several years. The Weiser River Soil Conservation District and Weiser River Irrigation District have been seeking funding for the project for a while now. We recieved funding through the Water Quality Program for Agriculture (WQPA) , The Idaho Department of Water Resources along with a loan as match. This will benefit our community greatly. The 13.5 miles from the Galloway spillway to the Snake River is how far the water travels and benefits our local farmers and ranchers mostly on the Weiser Flat area. The Galloway Ditch that delivers the irrigation water, is the lifeline of irrigated crops within 15,000 acres, in Washington County. At one time without the irrigation canal, those 15,000 acres were desert land. In the past the Weiser River SCD has actively sought and received funding to filter water going into the Snake River, from laterals along the Galloway Ditch. Most grants were received from the Idaho Department of Environment Quality 319 Grant Program.

Project description

Where the Weiser and Snake Rivers converge is the intake for the City of Weiser drinking water. We recently did a 319 project named City of Weiser Intake Project, this too was a great success in reducing sediment, phosphorus and nitrogent. A large sediment island had developed over the past 20 years, almost reaching the drinking water intake to the City of Weiser. Bill Lillibridge the engineer used by Conservation Districts noted that when you see a large sediment island like this, the culprit is about 1/4 mile upstream. We had just received approval to begin work on Monroe Creek, and that just happened to be the main culprit which was approximately 1/4 mile upstream. The fit for these two projects could not have been better. This project will have reductions of sediment, phosphorus and nitrogent. Sediment will be reduced, that would normally drain to the Weiser and Snake River, which was the problem that created a very large sediment island close to the City of Weiser Drinking Water Plant Intake.

Conclusion

The Weiser River SCD was awarded a 319 grant to begin streambank erosion along the 25 miles of Monroe Creek. At this point the original 319 project has been very successful with 4 landowners installing BMP's. Washington County Road and Bridge approached the District with a project along Chicken Creek. We requested an extension of $23,000 for this project to repair the eroded Chicken Creek Road and reduce sediment to Monroe Creek. We have now completed the Chicken Creek Project and plan on doing even more road repair. The request from Wa. Co. Rd & Bridge was for 3 miles as the road had been in need for several years. IDEQ had $23,000 for use as an extension of the Original 319 Monroe Creek Grant.

Objectives.

The objective was to address seven side draw culverts crossing under Monroe and Chicken Creek roads. Also to be rocking approximately 1 mile of road with the amount of funds we received from the extention. The 3 miles of road discharges directly to Chicken Creek and on down to Monroe Creek. Our main objectives is to address BMP's along as much of Monroe Creek as possible. This proved to be a main point of concern.

Project Title: Confluence Streambank Restoration Project.

The project focused on reducing the source of a large sediment bar in the mouth of the Weiser River. Original investigations pointed to the south side of the project reach as the source; further investigations determined that the sources are further upriver, sediment in Monroe Creek draining into the Weiser River. Bar formation is due to the river level interactions of the Weiser and Snake Rivers proximity to the project. The project then shifted to reducing the sediment bar and protecting nearby project banks with vegetated rip rap. Stabilize bank with rock rip rap and willow plantings.

Objectives.

The project focused on the formation and effects of a large sandbar in the middle of the Weiser River just upstream of its confluence with the Snake River. The bar is mainly formed from the interaction of the water levels of the two rivers – it waxes and wanes somewhat depending on the relative elevations of the two rivers during sediment transport events. The issue is exacerbated by railroad bridge piers that align the Weiser River towards the southwest, causing some bank erosion along the southern extent of the Weiser River mouth. In the grant application, sediment from the adjacent banks was identified as a major source of the sediment bar adjacent to the water plant intake. The formation of the sediment bar was causing the Weiser River to shift southwards and impinge upon the southern riverbank. The bar was extending downstream and creating problems with the City of Weiser water intake. Subsequent investigations also revealed a public hazard in the form of old concrete riprap with exposed rebar and significant voids at the western point of the Snake/Weiser Confluence that was addressed.

Methods.

Within the confluence reach, a large sand bar directly downstream of the railroad bridge, on the north side of the river, was reduced with project work. This allows the river to better flow between the river piles on the north half of the river and reduces forces pushing the sediment south. Willows were salvaged during removal and utilized as clump planting along the north side of the river in areas impacted by public use. These clump planting should aid in reducing “bank walking” by the public and stabilize the bank during high flow events. The permits were in place for the work but rising water levels during the 2019 construction window did not allow all work to be completed until 2020. Lightweight concrete riprap on the north side of the Weiser/Snake confluence was removed and replaced with clean angular rock. This replacement included significant riparian plantings in the vegetated riprap. The concrete removal will help with bank stability and remove safety issues with exposed rebar and riprap without adequate large-void filling. The new vegetated riprap will include access points for the public, but not allow the full-reach access of the current riprap.

A set of rock stairs utilizing flat riprap rock was installed near the boat launch.

Additional Information:

Also, upon further investigation, other sources are more likely contributing to the sediment bar, including Monroe Creek, which enters the Weiser River approximately 2,000 feet upstream of the confluence project. 319 project work is beginning to address sediment/nutrient issues on Monroe Creek. Other potential localized sediment sources include several compromised upstream levee banks, which have been addressed with FEMA assistance. Finally, the flood-stage interactions between the Snake and Weiser Rivers will often cause some bar formation from the regular sediment flow normal to all river systems.