Barriers to passage are one of the primary threats to Pacific Lamprey distribution and abundance throughout their range. In recent years, a number of major passage issues have been addressed in the Oregon South Coast Regional Management Unit (RMU), and an unprecedented four dams have been removed from the Rogue Basin in southern Oregon since 2007 opening the door to increased migratory capacity for Pacific Lamprey at all life stages in the region. Despite these important improvements, the Southern Oregon Coast Regional Implementation Plan notes that a number of existing structures continue to impede passage or alter the hydrography to the detriment of fish and aquatic wildlife in the Applegate Watershed (a subbasin of the Rogue River). The Applegate River is known to have spawning lamprey and has been identified as a river to target for lamprey conservation efforts within the Rogue Basin. Smaller dams and water diversions for municipal, irrigation, livestock and other uses are abundant within the South Coast sub-region. Contemporary structures are required to provide passage for migratory fish and maintain screening or by-pass devices to protect fish from impingement or entrainment.

Unfortunately, there are a large number of older structures that predate current screening and fish passage requirements. Additionally, active water rights associated with diversions make them difficult to upgrade or remove. Water diversion structures with inadequate screening or open irrigation canals can harm or entrap larval and juvenile lamprey while channel spanning concrete dams may delay or impede adult lamprey passage given their difficulty navigating over or around sharp edges (e.g., 90 degree angels), especially with high velocity (e.g., dams crest; Pacific Lamprey Technical Workgroup 2017).

Additionally, many salmonid barriers may also serve as passage barriers to lamprey, due to the right-angle concrete lip at the dam’s crest over which lamprey are often unable to navigate. This project will benefit upstream passage for migrating adults, through facilitating passage over dams that otherwise present a passage barrier with right angled concrete lips. Improving passage in the Applegate Watershed will potentially open up important spawning and rearing habitat for Pacific Lamprey. As passage is improved and Pacific Lamprey, partners are excited to watch them move back in to fully utilize the habitat available to them.

The Lamprey Passage for Small Dams in the Applegate Watershed Project targets six of these structures that present a passage issue to lamprey within the Applegate Watershed in the Rogue Basin. Many of these small dams can be modified at minimal cost to create a curve in the dam’s crest (such that lamprey can suction over) without impacting the water users or the dam’s integrity and structure. Due to the minimal impacts of these modifications to the dam itself, these passage retrofits represent “low-hanging fruit” for achieving adult upstream passage for lamprey across the basin at minimal cost. The Applegate Partnership & Watershed Council is leveraging its 2018 distribution survey to focus on barriers within systems known to support lamprey.

The six low-head dams targeted for this project include Murphy Dam and McKee Dam (mainstem Applegate River), Lovelace Dam (Slate Creek), Watts Topin (Williams Creek), Lower Philips Dam and Gin Lin Dam (Little Applegate River). Implementation of the project includes:
• Conducting water-user and landowner outreach, based on existing salmonid barrier assessments and partner knowledge, consulting with partners in the Rogue Basin Partnership’s Instream and Passage Working Group.
• Securing cooperative landowner agreements.
• These retrofits will be designed and implemented by a local passage expert from Western Fishes who has successfully retrofitted many such dams and pioneered many of the low-cost techniques using tubing and rounded stainless steel. Western Fishes will work with local partners: Grizzly Peak Working Group, Rogue Basin Partnership’s Native Species Working Group, USFWS and ODFW.

Human Interest/Community Benefit:

Pacific Lamprey are a culturally significant species and first food source for Native American Tribes throughout its historical range, and are also a tribal trust species for the USFWS and a state sensitive species for Oregon Department of Fish and Wildlife. The South Coast Regional Management Unit of PLCI has ranked passage as a threat for Pacific Lamprey, and allowing Pacific Lamprey to more fully utilize the Applegate Watershed will provide ecological, as well as human benefits to the region. The increased presence of lampreys in these watersheds will not only provide ecological benefits, but also increase awareness of this important species. Lack of awareness is also identified and a key threat to the recovery of Pacific Lamprey in this region.

Effectiveness monitoring for lamprey passage is very difficult given their nocturnal migration patterns and the site conditions at these specific barriers in the Applegate. The barriers that are retrofitted will be evaluated for the possibility of installing a video monitoring system. This will be the first monitoring station of this kind in Oregon south of the Umpqua, and will contribute valuable data on lamprey population in the region. Night surveys will be used to monitor the effectiveness of the retrofits at the other five barriers being addressed through this project.

Project Timeline:

Fall 2020 – Fall 2022

Project Partners:

• Applegate Partnership & Watershed Council*
• Bureau of Land Management
• Cow Creek Band of Umpqua Tribe of Indians
• Grizzly Peak Working Group
• Oregon Department of Fish & Wildlife
• Rogue Basin Partnership’s Native Species Working Group
• U.S. Fish & Wildlife Service
• U.S. Forest Service
• Western Fishes*