NWW-2019-00196: Owyhee County, Rippee Island Snake River Restoration Research

U.S. ARMY CORPS OF ENGINEERS PROJECT MANAGER:  
William Schrader
william.c.schrader@usace.army.mil
(208) 433-4471

PURPOSE:  
The purpose of this project is to reduce water temperatures in the Snake River through channel modification and to evaluate effectiveness of floodplain reconstruction methods. 

Modeling has demonstrated that decreasing the surface area of a water body will reduce water temperatures by reducing solar load, and this method of temperature reduction will be implemented in the project reach as part of an effort to meet water quality requirements for temperature within the Snake River.  Additionally, the project will construct new floodplain and evaluate the effectiveness of various floodplain restoration methods, including vegetation planting, wood placement, and swale construction.  The project is also expected to reduce macrophyte growth within the deepened channel, thereby improving navigation for boaters.  Finally, the project will improve substrate conditions for certain aquatic organisms within the project reach through the installation of gravels over disturbed floodplain and channel bed.  

Project activities are generally summarized as follows:  Excavating the river channel, increasing flow depth; narrowing the channel on the northeast side of Rippee Island and around the unnamed island by extending island banks into the river, increasing flow velocity; capping in-channel excavation and discharge with various gravels; and planting riparian vegetation, installing large wood, and creating swales to restore, reinforce, and shade the newly extended island floodplain and adjacent river.

WATERWAY:  
Snake River

LOCATION:  
The proposed project would be located on the Snake River at River Mile 436 within Section 27, Township 01 North, Range 03 West, near latitude 43.395º N and longitude –116.675º W, in Canyon and Owyhee Counties, approximately 7.5 miles west of the City of Melba, Idaho.  

DRIVING DIRECTIONS:  
From Nampa, Idaho, travel South on Highway 45 for approximately 14 miles. Turn right (west) on Map Rock Road (north of the Snake River) and continue for approximately 3 miles.  The project is located near Rippee Island in the Snake River, as well as on private property to the northeast side of the river.

AUTHORITY: 
This permit will be issued or denied under the authority of Section 404 of the Clean Water Act (33 U.S.C. 1344) and the authority of Section 10 of the Rivers & Harbors Act of 1899 (33 U.S.C. 403).  A Department of the Army (DA) permit is required for the discharge of dredged or fill material into waters of the United States, including wetlands. A DA permit is also required for work or structures waterward of the ordinary high water mark located in or over navigable waters of the U.S., including the excavation, dredging or deposition of material in navigable waters, or any alteration obstructing or affecting the course, location, condition, or capacity of the navigable waterway.

WORK:
The applicant proposes the following work (all quantities are approximate):

• Site preparation, including:
  • Marking of haul routes and staging areas.
  • Installation of construction fence.
  • Installation of erosion control measures (i.e., filter fabric silt fences, straw wattles, or similar barriers).
  • Stockpiling imported vegetation and salvaging vegetation from work areas for later use during site restoration.
  • Turbidity monitoring will be conducted at regular intervals and during specific activities throughout the project to ensure water quality standards are met.
• In-water work area isolation, including installation of 15,500 cubic yards of temporary coffer dams across 2 acres along 600 linear feet of river channel and deployment of floating silt curtains, both of which will be located upstream and downstream of Rippee Island in the Snake River.
  • Coffer dams will be constructed using a bulk bags/earthen dam combination or portadam structures where appropriate.
  • Fish salvage will be conducted in isolated areas via electroshocking, and any captured fish will be quickly and properly transported to and released into the Snake River adjacent to the project area.
  • De-watering behind coffer dams will be conducted and sustained using pumps, and pumped water will be treated using areas isolated by silt curtains, settling ponds, or other methods as needed to ensure suspended sediment is reduced to acceptable levels prior to release back into the Snake River.  Turbidity monitoring will be conducted specific to this activity.
• Excavation of up to 84,700 cubic yards of channel materials across 15.5 acres along 3,500 linear feet in the Snake River to an average of 3 feet below the current bed level. 
  • The goal of excavation is to deepen the channel of the Snake River and procure materials for Rippee Island expansion.
  • Organic material (2,000 cubic yards) and 7,000 cubic yards of excess material will not be re-used in construction activities and will be disposed in an approved site. 
  • An additional 5,700 cubic yards of over-excavation may be required for zone gravels placement (included in 84,700 cubic yard estimate).
• Discharge of 124,500 cubic yards of material over 34.2 acres along 3,500 linear feet of the Snake River, including island expansion adjacent to Rippee Island and an unnamed island by discharging 70,000 cubic yards of excavated bulk fill material across 18.7 acres and capping channel disturbance and fill using 43,100 cubic yards of imported zoned gravels below ordinary high water mark across 15.5 acres of river channel and 11,400 cubic yards of imported cap gravels across 18.7 acres of new island/floodplain.
  • The goal of this discharge is to reduce water temperatures in the Snake River by expanding Rippee Island and a small, unnamed, adjacent island into the main channel of the Snake River.  Expansion will primarily reduce channel surface area, and will secondarily increase flow depth and velocity, all of which are expected to decrease solar load accumulated in the project reach. 
  • Zone gravels will be used as riverbed substrate, while cap gravels will be used as island/planting substrate; see “Additional Information” below for gravel depths and placement locations.
  • All excavated bulk fill material will be capped with imported fill gravels.
  • Some discharge will occur outside of the coffer dammed area upstream of Rippee Island, but discharge will be behind silt curtains.  Turbidity monitoring will be conducted specific to this activity.
• Floodplain construction and plantings across 18.7 acres of newly created floodplain and any other disturbed areas on Rippee and an unnamed island, including:
  • Construction of swales and ridges in the island floodplain.
  • Installation of 50 small logs with limbs per acre of new/disturbed island to increase floodplain roughness.
  • Planting 150 various native willows, dogwoods, skunkbrush, currant, and rose per acre of new/disturbed island to restore disturbed areas and increase floodplain roughness; planting will likely be done via stingers.
  • As part of the research component of this project, plantings will not be irrigated and will instead rely on the low water table in the project area.
  • See “Proposed Mitigation” section below for more details regarding vegetation management.
• Repair of three (3) irrigation drains within the project area which are currently in a state of disrepair and are contributing fine sediment to the project area.
  • Repair of drain 1 and 2 will be conducted within the boundary of the dewatered work area.  As drains will still be active during activities, discharge will be captured and rerouted back to the Snake River through the dewatered work area via ditches, piping, or similar methods.
  • Repair of drain 3, which is upstream of the isolated work area, will be conducted in the dry (either naturally or by artificial isolation and dewatering) or behind silt curtains.
  • Repairs will include the installation of new pipe and placement of riprap, requiring the excavation of 40-90 cubic yards per site and discharge of 90-150 cubic yards of riprap per site, and native backfill of 160 cubic yards at drain 2. 
  • Removed pipe and excess materials will be disposed of in an approved site.
• Site restoration, including:
  • Removal of coffer dams, including strategically rewatering the work area to ensure suspended sediment levels are minimized.  Turbidity monitoring will be conducted specific to this activity.
  • Revegetation disturbed areas via seeding or live planting, and restoration of any agricultural land to its state prior to use.
  • Installation of monitoring wells within the island extension floodplain to measure the depth to groundwater.  Wells are low-profile and are expected to remain in place for several years after activities are finished.
  • Any disturbed bankside will be restored to a natural slope and be revegetated with vegetation similar to adjacent bankside in the area.

ADDITIONAL INFORMATION: 
The main stem Snake River has been highly altered as a result of changes in flow due to upstream water uses, increased inputs of nutrients and fine sediments from agricultural run-off, and increases in water temperature due to reduced flows and velocities, resulting in increased aquatic plant growth and static physical conditions of the river.  In order to counteract these altered river conditions, Idaho Power is conducting a demonstration research project on the Snake River adjacent to Rippee Island at River Mile (RM) 436.  This is the second island modification research project conducted in the Snake River by Idaho Power; the first was an expansion of Bayha Island at RM 439.5 (DA No.:  NWW-2014-00446).

Sediment sampling and analysis in the project area has been reviewed to ensure dredged material is suitable for re-deposition back into the river.  The review was conducted per the Sediment Evaluation Framework for the Pacific Northwest[1], which was developed by the Portland District Corps of Engineers sediment evaluation team (PSET) comprised of staff from the Portland District Corps of Engineers, Walla Walla District Corps of Engineers, Environmental Protection Agency Region 10, Washington Department of Ecology, Washington Department of Natural Resources, Oregon Department of Environmental Quality, Idaho Department of Environmental Quality, National Marine Fisheries Service, and U.S. Fish and Wildlife Service.

The analysis revealed elevated levels of nickel (42.1 mg/kg) at the Rippee Island site, exceeding the standard of 26 mg/kg established in the framework and the 11.8 mg/kg observed in the other nearby testing sites (Ware Island and Bernard Landing).  To address these elevated levels, dredge material reused as fill for island expansion will be capped with imported gravels:  Floodplain reconstruction will be covered with 0.5 feet of cap gravels, slopes will be covered with 1.5 to 2.5 feet of zone 1, 2, and/or 3 gravels, and the disturbed channel bed will be covered with 1 foot of zone 2 gravels.  PSET has determined that this method of confined placement will maintain water quality standards considering the level and type of contamination present in the dredge/fill material.

AQUATIC RESOURCE DESCRIPTION: 
The project area is located 5.25 miles downstream of the State Highway 45 Bridge crossing over the Snake River at Walters Ferry.  The project area consists of Rippee Island, two adjacent unnamed islands, and the channel of the Snake River.  The Snake River at the State Highway 45 bridge crossing is roughly 520 feet wide.  At the center of Rippee Island, the river channel is 1,500 feet wide from bank to bank, including the width of Rippee Island; the north and south wetted channels appear to be 400 and 320 feet wide, respectively.  The channel on the north side, which will be modified by project activities, is currently 4 feet deep on average during 50% exceedance flows (7,942 cfs). 

The project site is within the Marsing Reach of the Snake River and consists of a large, stable channel that is exceptionally wide and low-gradient.  Historically, Rippee Island has been used primarily for recreation purposes such as water fowl hunting and fishing.  Islands in the Snake River, including Rippee Island, are part of the Deer Flat National Wildlife Refuge managed by the U.S. Fish and Wildlife Service, which begins in the Snake River at the Canyon/Ada County line and ends at Farewell Bend, Oregon (approximately 113 river miles).  The floodplain adjacent to the project area is predominantly used for agricultural production.

In general, the river at the project site is wide and shallow with a dominance of invasive aquatic macrophytes and substrate impacted with coarse to fine sand.  Riparian vegetation is primarily ground vegetation and provides little shade.  The Marsing Reach of the Snake River has been heavily impacted from fine sediment from agricultural runoff, increased water temperature due to reduced flows and shallow water depths, and the proliferation of invasive aquatic plants.

ANTICIPATED IMPACTS ON AQUATIC ENVIRONMENT: 
The proposed project would impact a total of 2.38 acres of wetlands, 97% of which is emergent, 1% scrub/shrub, and 2% forested.  The majority of this disturbance is related to island expansion; however, coffer dam construction would disturb 0.036 acres of predominantly emergent wetland.

The proposed project would impact a total of 31.82 acres of the river channel below the ordinary high water mark.  Dredging activities will occur across 15.5 acres of river channel and fill activities associated with island expansion will occur across 16.32 acres of river channel (18.7 acres total, including wetlands).

CONSTRUCTION PERIOD: 
The applicant proposes to start construction in the summer between 2020 and 2023.  The permit would authorize construction to take place over the course of up to one (1) year, though in-water construction activities must be completed before high spring flows, including removal of isolation measures and establishment of floodplain features.  Dewatering will likely be in effect from July through November, though this window could vary depending on site conditions.

PROPOSED MITIGATION: 
The applicant proposes the following mitigation measures to avoid, minimize, and compensate for impacts to waters of the United States from activities involving discharges of dredged or fill material. 

The project would disturb 2.38 acres of predominantly emergent wetlands.  The project proposes to restore disturbed/constructed areas with native willows (Salix exigua, etc.), dogwood (Cornus sericea), currant (Ribes aureum), rose (Rosa woodsia), cottonwood (Populus trichocarpa), and other appropriate vegetation.  Overall, much of the emergent wetland disturbed by project activities will be replaced by scrub/shrub wetland, with some potentially meeting the definition of forested wetland.  All currently existing scrub/shrub and forested wetland is expected to be replaced by restoration activities.  Therefore, no net loss of wetland area or functional value is expected as part of project activities.  With the addition of island expansion, wetland area is expected to increase by 16.4 acres.  Prior research projects (i.e., Bayha Island) with similar restoration plans have demonstrated successful vegetation retention.  While the majority of new vegetation on the Bayha Island project was irrigated, some test plots were excluded from irrigation to evaluate the effectiveness of natural vegetation retention.  These test plots did not show any notable difference in retention compared to irrigated plots; therefore, it is reasonable to expect that unirrigated vegetation on Rippee Island will be successful.  In the event of a low water year or other condition that may threaten water delivery, an irrigation contingency plan has been developed and will be implemented as necessary.  In summary, all disturbed wetlands will be replaced with native vegetation at over a 7:1 ratio, with 97% of wetlands disturbed being converted from emergent to scrub/shrub using establishment methods verified by prior projects.  Therefore, proposed restoration activities are preliminarily determined to be sufficient to meet mitigation requirements for the 2.83 acres of wetlands disturbed by the project.

The proposed project would impact a total of 31.82 acres of river channel below the ordinary high water mark.  Currently, the river channel in the project area is shallow, prone to supporting overgrowth of macrophytes, and substrate is embedded predominantly fine sediment and/or sands.  Activities are anticipated to deepen and narrow the channel, reducing solar load in the Snake River (and thereby water temperatures), reduce the presence of aquatic macrophytes in the project area, and enhance substrate in the project area for certain aquatic organisms through the addition of gravels.  Therefore, considering the beneficial effects of project activities, proposed restoration activities are preliminarily determined to be sufficient to meet mitigation requirements for the 31.82 acres of river channel impacted by the project.

OTHER ENVIRONMENTAL DOCUMENTS AND DA PERMITS ISSUED TO APPLICANT:
Additional documents provided for USACE evaluation include the following:

• Vicinity Map (Exhibit A) dated June 11, 2019
• Project Design Report (Exhibit C) dated May 2019, including:
  • Wetland Delineation (Appendix C) dated November 2018
  • Hydrologic Summary (Appendix D)  dated November 2012
  • Ordinary High Water Mark Delineation (Appendix E) dated November 2018
• Biological Assessment (Exhibit D) dated June 2019
• Cultural Resource Inventory (Exhibit E) dated May 2019
• Analysis of Public Interest Factors (Exhibit F) dated June 2019
• Access, Staging, and Mining Map (Exhibit G) dated August 2019
• Sediment Suitability Determination Memo (Exhibit J) dated July 2019

Other permits issued to Idaho Power associated with the research project include the following: 

• Nationwide Permit No. 06:  Survey Activities issued on September 5, 2014 to conduct sediment sampling
• Nationwide Permit No. 05:  Scientific Measurement Devices issued on May 20, 2015 to install temperature and water level monitoring equipment
• Department of the Army Permit for Bayha Island Enhancement Research Project issued on June 10, 2016 to modify Bayha Island in an effort to research temperature reduction and floodplain construction in the Snake River
• Nationwide Permit No. 05:  Scientific Measurement Devices issued on November 15, 2017 to install water level monitoring equipment

WATER QUALITY CERTIFICATION: 
This notice will also serve as a Public Notice that the Idaho Department of Environmental Quality (IDEQ) is evaluating whether to certify that the discharge of dredge and/or fill material proposed for this project will not violate existing water quality standards.  A Department of the Army permit will not be issued until water quality certification has been issued or waived by the IDEQ, as required by Section 401 of the Clean Water Act.  If water quality certification is not issued, waived or denied within sixty (60) days of this public notice date, and an extension of this period is not requested by and granted to the IDEQ, certification will be considered waived.  Additionally, within thirty (30) days of this Public Notice, any person may provide written comments to IDEQ as request in writing that IDEQ provide them notice of their preliminary 401 Certification decision.

Comments concerning Water Quality Certification for this project should be mailed to: 

Idaho Department of Environmental Quality
1445 North Orchard Street
Boise, ID  83706-2239

OTHER AUTHORIZATIONS: 
The proposed project would require approval from the Idaho Department of Water Resources under the Idaho Stream Channel Protection Act; a submerged land easement from the Idaho Department of Lands; and a Section 401 Water Quality Certification from the Idaho Department of Environmental Quality.  Should any work above the ordinary high water mark on Rippee Island or the adjacent unnamed islands be necessary, a Special Use Permit from U.S. Fish and Wildlife Service may be required.

CULTURAL RESOURCES: 
Coordination is currently being conducted with the Idaho State Historic Preservation Office to determine if this activity will affect a site that is listed on the National Register of Historic Places, or a site that may be eligible for listing on the Register.  Coordination is also being conducted with the appropriate Tribal entity or the Tribal Historic Preservation Offices for the Shoshone-Bannock Tribes and Shoshone-Paiute Tribes to determine if there are any tribal historic or cultural interests within the project area. 

TRIBAL TREATY RIGHTS AND INTERESTS: 
Federal agencies acknowledge the federal trust responsibility arising from treaties, statues, executive orders and the historical relations between the United States and American Indian Tribes.  The federal government has a unique trust relationship with federally recognized American Indian Tribes, including the Shoshone-Bannock Tribes and Shoshone-Paiute Tribes.  The U.S. Army Corps of Engineers (USACE) has a responsibility and obligation to consider and consult on potential effects to Tribal rights, uses and interests.  USACE further recognizes there may be a need for additional and on-going consultation. 

ENDANGERED SPECIES: 
The project is within the known or historic range of the Snake River Physa snail (Physa natricina), which is currently listed as “Endangered” by the U.S. Fish and Wildlife Service (USFWS).  Coordination is currently being conducted with the USFWS to determine if the activity will have any effect on species or designated critical habitat protected under the Endangered Species Act of 1973 (87 Stat. 844). 

ESSENTIAL FISH HABITAT: 
The Magnuson-Stevens Fishery Conservation and Management Act, as amended by the Sustainable Fisheries Act of 1996, requires all Federal agencies to consult with the National Marine Fisheries Service on all actions or proposed actions, permitted, funded or undertaken by the agency that may adversely affect Essential Fish Habitat (EFH).  No EFH species are known to use the project area.  Preliminarily, a determination of “No Effect” has been made for EFH.

ENVIRONMENTAL IMPACT STATEMENT: 
Preliminary review indicates the proposed activities will not require preparation of an Environmental Impact Statement.  Comments provided will be considered in preparation of an Environmental Assessment. 

EVALUATION: 
The decision whether to issue a permit will be based on an evaluation of the probable impact, including cumulative impacts, of the proposed activity on the public interest.  This decision will reflect the national concern for both protection and utilization of important resources.  The benefit which reasonably may be expected to accrue from the proposal must be balanced against its reasonably foreseeable detriments.  All factors which may be relevant to the proposal will be considered, including the cumulative effects thereof; among those are conservation, economics, aesthetics, general environmental concerns, wetlands, historic properties, fish and wildlife values, flood hazards, floodplain values, land use, navigation, shoreline erosion and accretion, recreation, water supply and conservation, water quality, energy needs, safety, food and fiber production, mineral needs, consideration of property ownership and in general, the needs and welfare of the people.  In addition, our evaluation will include application of the EPA Guidelines (40 CFR 230) as required by Section 404(b)(1) of the Clean Water Act. 

CONSIDERATION OF PUBLIC COMMENTS:  
USACE is soliciting comments from the general public; Federal, State and local agencies and officials, Tribal entities and other interested parties in order to consider and evaluate the impacts of this proposed activity.  Any comments received will be considered by USACE to determine whether to issue, modify, condition or deny a permit for this proposal.  To make this decision, comments are used to assess impacts on endangered species, historic properties, water quality, general environmental effects and the other public interest factors listed above.  Comments are used in the preparation of an Environmental Assessment and/or an Environmental Impact Statement pursuant to the National Environmental Policy Act.  Comments are also used to determine the need for a public hearing and to determine the overall public interest of the proposed activity.

PUBLIC HEARING: 
Any person may request in writing, within the comment period specified in this notice, that a public hearing be held to consider this proposed activity.  Requests for a public hearing shall state specific reasons for holding a public hearing. A request may be denied if substantive reasons for holding a hearing are not provided or if there is otherwise no valid interest to be served.

COMMENT & REVIEW PERIOD: 
Interested parties are invited to provide comments on the proposed activity, which will become a part of the record and will be considered in the final decision. 

Please mail comments via post to:

U.S. Army Corps of Engineers

ATTN:  William Schrader

720 East Park Boulevard, Suite 245

Boise, Idaho  83712-7757

Please mail comments electronically to:

william.c.schrader@usace.army.mil

To discuss this project, please call:

William Schrader at (208) 433-4471

Comments should be received no later than the comment due date of October 30, 2019, as indicated on this notice, to receive consideration.

                                                                  Kelly J. Urbanek

                                                                              Chief of Regulatory, Walla Walla District