Knife River Habitat Restoration

STREAM CONNECTIVITY

The single, largest barrier affecting stream connectivity in the Knife River watershed occurred at the Second Falls on the main Knife River, approximately three miles upstream from Lake Superior.  This barrier blocked fish from ascending upstream to the fertile spawning areas inland.  Originally, swim pockets allowed easy passage,  then the DNR blasted the pockets and installed a cement weir.  The weir worked well until it blew out around 2005.

After great effort, the LSSA gained the support of the DNR to remedy the barrier.  After meeting with the DNR pinning large boulders in place to create a deep jumping pool was agreed on by all parties.  

The LSSA approached LSOHC to modify Phase I’s scope of work with support from Comm. Landwehr and Director Boggess.  Once LSOHC approved the change, the project came together in just a few weeks.  Permits were obtained, four large rocks were donated at no charge by Cliffs Natural Resources-North Shore Mining and the project begun under the direction of the MNDNR.

The best two boulders were chosen and mobilized to the site.  In less than three days the boulders were placed and pinned to the bedrock.  The placed boulders created the needed jumping pool immediately below the falls.  Monitoring has confirmed that fish can now easily pass the former barrier in most flows to gain access to the fertile spawning grounds upstream throughout the entire watershed.

We had excellent cooperation from St. Louis County Forestry and the MN DNR.

TREE PLANTING:

The Lake Superior Steelhead Association (LSSA) has long believed that a healthy watershed includes a healthy and diverse riparian zone.  During the initial walk through under Phase I, a superb planting site was noted in the Main West Branch, with excellent access via the North Shore State Trail.

A plan was immediately established for a LSSA ‘volunteer’ plant in the spring of 2013.  The BMP for riparian plantings presently is that of a mix of coniferous and deciduous species to provide a more diverse forest.  The LSSA also wanted to expand the plantings to include species that may become common due to future climate change.  The species to be included in our riparian zone plantings in Phase I included tamarack, white spruce, silver maple, river birch and swamp white oak.  The listed species are all native to Minnesota and were approved by the MN DNR.

Following the successful 2013 plant, LSSA members came back in 2014 to plant 150 deciduous trees at the same site.  Also in the spring of 2014, Conservation Corp Minnesota planted hundreds more deciduous trees  in another beaver meadow just downstream from the volunteer site.

One major lesson learned was that larger sized trees are needed in order to compete with the invasive reed canary grass found throughout the watershed in old beaver meadows.

We had excellent cooperation with both the MN DNR and the St. Louis County Forestry Dept. for our planting work.

STREAM ASSESSMENT

Before any rehabilitation project could begin in the watershed, the LSSA realized that information must be gathered that would allow us to prioritize any future rehabilitation efforts.

Water temperature was a key so 23 temperature loggers were deployed throughout the watershed.  Loggers were in place from June 1 through September 30 so that the data would coincide with data collected by the MNDNR.  This data determined where juvenile trout could survive and grow, which provided a habitat restoration focal point.

The Main West Branch and major unnamed tributaries were assessed for stream conditions, possible connectivity blockages, the state of the riparian cover, condition of stream banks, the location of adult spawning habitat and availability of juvenile holding habitat.  The identified impacts were compiled and overlaid with water temperature data so rehabilitation priorities could be selected based on stream biology.  

One fact quickly learned was the significant impact of past and present beaver activity in the watershed.  One unnamed tributary had 29 current or historic dams in just over six miles of stream.  The beaver meadows created by these dams allow for invasive reed canary grass to infiltrate throughout the riparian zone eliminating any regeneration of trees.

Through the assessment, the LSSA learned that more spring inflow occurred than originally thought by the MNDNR.  We are now able to predict where trout can live, thrive or parish based on water temperature.

BLACK ASH

In the Scope of Work for Phase I of our Knife River Habitat Restoration Grant, identification and possible under plantings in black ash stands were discussed.  The emerald ash borer (EAB) has the potential to wipe out huge tracts of black ash stands through out the United Sates.  According to Laurentian RC& D GIS data, the Main West Branch has over 10 miles of black ash cover in the immediate riparian zone.

During the assessment portion of Phase I, field notes and GPS coordinates were taken on black ash stands throughout the Main West Branch.  Technological advances have improved making identification of specific tree species possible by satellite imagery.  LIDAR and color infrared imagery (CIR), when combined, give the height, mass and specific electromagnetic spectrum to plants.  

Black ash is rather unique in that it is usually the last to leaf out in the spring and one the earliest to lose its leaves in the fall.  Using our field data and comparing the CIR imagery for the area after black ash had lost their leaves and other deciduous trees maintained their leave cover, we could identify areas that held black ash.

Our work was very timely in that the EAB has now been identified in Duluth’s Park Point neighborhood, most recently, in far eastern Duluth.

One major item learned from both CIR/LIDAR imagery and verified in the field is that black ash stands are of mixed deciduous species-ash, maple and some yellow birch making under planting less imperative.