When barriers are involved in a river, the Great Lakes Fishery Commission completes an investigation of the entire watershed to determine any sea lamprey spread. Even now, with a barrier in place, sea lamprey surveys are conducted in the upper Grand River to look for escapement. The size and complexity of the Grand River and its tributaries present significant challenges and costs associated with conducting Sea Lamprey Control Program activities in the watershed. Investigative field work will take place prior to and during the construction of the proposed lamprey barrier. Following construction, an increased level of barrier performance monitoring will commence including trapping of adult sea lampreys, eDNA sampling and larval assessment. Like most major sea lamprey producing streams, including the Grand River, the monitoring phase is expected to continue in perpetuity. If sea lampreys are found above the newly proposed barrier, the Great Lakes Fishery Commission is prepared to undertake mitigation measures that include shoring up dams upstream of Grand Rapids (e.g., the Ada Dam, the Weber Dam) to ensure sea lamprey blockage, deployment of portable electric barriers and traps to prevent sea lamprey migration into critical habitat, and lampricide applications to remove sea lamprey larvae from the river and its tributaries.

Sea lampreys enter the Grand River from Lake Michigan and inhabit the river downstream of the Sixth Street Dam. That stretch of the river contains poor sea lamprey habitat and the stretch is not productive enough to warrant treatments in the Grand itself. Crockery and Norris creeks, located downstream of the Sixth Street Dam, are treated regularly. The upper Grand River and its tributaries have been regularly surveyed for sea lampreys since 1962. A total of 44 tributaries upstream of the Sixth Street Dam have been surveyed. Harmless, native lampreys are also known to occupy reaches of the watershed upstream of the Sixth Street Dam. 

Two previous sea lamprey escapement events have been noted upstream of the Sixth Street Dam. Larval sea lampreys were collected from Lowell Creek in 1962 and the stream was treated with TFM (3-trifluoromethyl-4′-nitrophenol) in 1965. Larval sea lampreys were collected from the Rogue River during 2008, resulting in a treatment in 2009. The source(s) of escapement for each event is unknown. 

Recent larval assessment sampling in 2022 identified several large sea lamprey larvae in the Rogue River likely a result of flooding in the spring of 2020 when the Sixth Street Dam was submerged with high water. Additional evaluation and assessment of this finding, and the need for a lampricide treatment, is currently underway with the U.S. Fish and Wildlife Service Sea Lamprey Control Program and Great Lakes Fishery Commision.

The City of Grand Rapids, GRWW, and our project partners, have consulted with technical leadership from the State of Michigan Department of Natural Resources and believe the AHS barrier could preserve opportunities to prevent upstream migration of Asian carp in the future.

The Michigan DNR depends on sea lamprey control for the success of its fishery management program. Without sea lamprey control, the state would not achieve its fishery objectives. A sea lamprey infestation of the Grand River and its tributaries would harm the entire Lake Michigan fishery and probably harm Lake Huron. A new sea lamprey barrier will prevent the spread of sea lampreys into the Grand River and its tributaries upstream of Grand Rapids and, therefore, is integral to the DNR’s objectives of reducing the number of sea lampreys in the Great Lakes.

The operations, management and maintenance associated with a new sea lamprey barrier has been discussed for many years and is recognized as a top priority. A multi-agency public/private governance structure is being developed to further address governance concerns surrounding the proposed new barrier. Management of this structure will also include significant public and private input from a variety of river user groups, regulatory agencies and upstream/downstream communities.

The City and GRWW’s proposed location of the AHS structure is approximately one mile upstream of the Sixth Street Dam and will be located just downstream of the train trestle bridge that crosses the Grand River south of Ann Street. This location is at the head of the historic, and regionally rare, limestone rapids and will provide enhanced access to approximately 88 acres of limestone bedrock habitat. 

This location also creates additional opportunities to reimagine our city parks and trail system as envisioned by the River For All community master plan. If the AHS was the selected alternative for the upper reach project and built at this site, and if the public safety hazards created by the existing dams are removed, there would be ample opportunities to think differently about flood protection and to provide improved access to the river in downstream city parks.

The AHS does not alleviate flooding. Any properties that currently flood will continue to flood and those properties that are required to carry flood insurance will continue to have this requirement. Sea lamprey barrier management was designed and evaluated to be effective when the flood levels are slightly lower than the existing flood levels in order to show effectiveness without harmful interference on properties. The potential reduction in flood levels is insignificant.

The historic rapids once found in Grand Rapids are regionally rare and two thirds of them are submerged under water upstream of the Sixth Street Dam. Our intent is to open the historic waters known to the Grand River Bands of Ottawa Indians as Gitchi Bawating, the Great Rapids. Returning the rapids will do good things for the river’s health and biodiversity. However, we share the concern of local, state and federal agencies that are tasked with controlling invasive sea lamprey. We have designed our project to stop sea lamprey before they move into upstream tributaries to spawn. Lamprey spawn in the spring. During those months, the lamprey barrier would act like Sixth Street Dam, preventing lamprey from reaching spawning tributaries upriver.

Scientists are testing technology downstream of the Boardman River’s Union Street Dam in Traverse City. This initiative, known as FishPass, aims to identify and refine technology to block undesirable species like sea lampreys while allowing the passage of desirable species like sturgeon. Technology developed at the Union Street Dam in Traverse City could be used in a lamprey barrier structure in the Grand River to maximize the passage of desirable fish while blocking sea lamprey and other undesirable species.