City of Madison

City of Madison Engineering | Photo Credit: Archie Nicolette



Tenny Park Shoreline and Path area

The City of Madison Parks and Engineering Divisions are proposing a 2015 project to stabilize and restore the shorelines around Tenney Lagoon.  The park path that parallels Johnson Street will be reconstructed in conjunction with the shoreline work, and approximately 300 ash trees will be removed in preparation for Emerald Ash Borer.  


Work began on July 7 and will continue throughout the summer.  Plans showing the work to be completed can be found here.

A list of tree removals can be found here.

Proposed species for revegatation project can be found here.


Questions and comments about the project can be directed to:

Sally Swenson, City Engineering - Shoreline: (608) 266-4862

Sarah Lerner, City Parks - Shoreline: (608) 261-4281

Corey Stelljes, City Engineering – Bike Path: (608) 266-9721

Tony Fernandez, City Engineering – Bike Path: (608) 266-9219


The City held a Public Information Meeting for the project on January 13, 2015.  Notice of the meeting was mailed to 1400 addresses, identified on the City’s website, social media outlets, and issued through a news release.   The PowerPoint presentation from this meeting can be found here.

City staff attended the Tenney-Lapham Neighborhood Association (TLNA) meetings on December 11, 2014 and April 6, 2015 to discuss the project.  Meeting minutes can be obtained through the TLNA.

City staff met with members of the Friends of the Yahara River Parkway to discuss the project on April 29, 2015.

The project was discussed in the Tenney-Lapham Neighborhood Association Winter and Spring newsletters, which can be found here.

A write-up of the project can also be found here, in the EastSide News.



The Tenney Park bike path that parallels Johnson Street is in poor condition and will be reconstructed as part of the overall 2015 project. Some salient points of the reconstruction include:

  • The new alignment will be similar to the existing alignment with minor changes to protect trees.
  • The path will be widened from 8 to 10 feet.  A 10-foot wide path is significantly more durable for maintenance vehicle traffic. 
  • Cut stone will be used to stabilize the shoreline in areas where the path is very close to the lagoon.
  • Three light poles will be added between the bus stop and the Johnson Street/Marston Avenue intersection.  The poles and lights will be the same as were installed on the Southwest Bike Path, which are warm spectrum, LED lights with focused light to prevent spill-over.  The poles are 20 feet tall and painted mate black.

The bike path reconstruction will occur early in the project, so as to be reopened before school starts.  The bike path will be closed during reconstruction.


Much of the shoreline around Tenney Lagoon, along both the mainland and the island, shows signs of instability and erosion.  The erosion is the result of several factors, the most significant of which are non-cohesive soils, insufficient root mass, and muskrat damage. 

Image of shoreline along Marson Ave

This image is of the shoreline along Marston Avenue.  The turf grass doesn't’t provide adequate stabilization, causing vertical banks, which are more vulnerable to erosion and muskrat burrowing.


Shoreline along Marson Av

This image is of the shoreline along Marston Avenue.  The turf grass doesn't’t provide adequate stabilization, causing vertical banks, which are more vulnerable to erosion and muskrat burrowing.

The 2015 project proposes to stabilize the banks via two methods: vegetated buffers and coir logs. In some areas the installation of these stabilization methodologies will be coordinated with invasive brush removal. Vegetated buffers and coir logs are described in more detail in the following sections.

Vegetated Buffer

Through seeding and plug planting, a buffer of native vegetation will be established along areas that are currently turf grass, provided the bank slope lends itself to this treatment.  The buffer will extend approximately 10 feet park-ward, from the normal water line.  Native vegetation has significantly deeper root systems than turf grass, and species will be matched with water levels, to create a root system that stabilizes the weak soils around the lagoon.

zones of a freshwater vegetated shoreline

This figure depicts a general image of a vegetated buffer.  Specific species have not yet been defined, but will be native to the area.  A list of the specific plants we plan to use will be added at a later date.

Coir Logs

Coir logs are durable, densely packed, coconut fiber log used to stabilize eroding banks.  Coir logs are semi-permanent, meaning they require several seasons to degrade.  The can be seeded or planted with plugs to establish vegetation and a stable toe.  We are proposing the placement of coir logs in areas where trees are close to an eroded shoreline. This will allow us to rebuild the toe of the shoreline instead of removing vegetation in order to create a stable slope. 

water level

Coir log installed in a waterbody

This figure shows a coir log installed in a waterbody, although not in the exact same configuration as is proposed for Tenney Lagoon.  In this project, we plan to grade and replant the area between the coir log and shoreline.

New coir log and one that is seasoned

This photo shows a new coir log, and one that has a season or two to become vegetated.  Coir logs take several years to completely degrade, and therefore will be visible for some time.

Muskrat Deterrent

Once the shorelines have been repaired, it will be important to keep the lagoon’s healthy muskrat population from re-damaging the area.  The most extensive damage appears to be in the more open areas, especially the shoreline near the Marston Avenue and Johnson Street intersection.  Therefore, in these open areas, we are proposing to trench (vertically) approximately 3 feet of galvanized hardware cloth into the bank.  This will prevent muskrats from constructing dens in the banks, which then collapse and leave the shoreline vulnerable. 

layout of muskrate deterent

Invasive Removal

As part of the shoreline stabilization, we are proposing to remove large amounts of invasive brush, mainly european alder and buckthorn.  Ultimately, we believe this will be beneficial to the park for two reasons: it will improve native habitat and facilitate establishment of vegetation that is in accordance with the historic planting plans.  However, the removal of large sections of brushy vegetation will cause a significant visual impact to the park. 

Tree Removal

A tree survey was conducted in late 2014.  The blue tags on the trees are identification tags. Corresponding data for each tree can be found here

In conjunction with this project, trees will be removed for three reasons: shoreline work, bike path reconstruction, and ash removal.  By far, the most significant of these will be ash removal due to Emerald Ash Borer.

  • Approximately 15 trees will be removed due to work along the shoreline.  These trees either have severely undercut root masses, are invasive species, or have a severe lean and therefore cannot be saved. 
  • Six trees will be removed as part of the bike path reconstruction.  When possible, the alignment of the path was altered to preserve trees.  However, in locations where there are trees close to the path on both sides, or the path is very close to the shoreline, removals will be necessary.
  • The tree survey identified 197 ash trees growing near the lagoon.  Of these 197, approximately 70% are already in poor or declining health.  In anticipation of EAB infestation, the City will use this opportunity to remove these ash trees before they become a hazard or nuisance.  In addition to the ash trees identified in the tree survey (which was limited to along the lagoon shoreline), there are approximately 100 additional ash trees in poor health that will be removed in 2015, for a total of approximately 300 trees to be removed at Tenney Park.


Shoreline Access

The vegetative buffer will have taller and denser vegetation than is currently growing along the existing shoreline.  Therefore, the project proposes to construct specific shoreline access points around the lagoon.  The majority of these access points will be where existing benches are currently located, and will likely be comprised of cut limestone.  The shoreline in front of the shelter will be kept open for lagoon access.  Additionally, sloped access points will be created with reinforced turf to provide access for maintenance vehicles.  These access points will also serve as canoe access.


Park Impacts

This project will have significant impacts on park use between July and November 2015.  The shelter will not be available for reservations during the project. The bike path along Johnson Street will be detoured during the path reconstruction, and the bike path along Thornton Avenue will be periodically detoured for short periods. Access to the island will be prohibited while the contractor is working on that shoreline.  Specific schedules for upcoming closures will be available after the contract has been awarded.

The lagoon will be drained during the project to provide more stable working conditions and prevent excessive amounts of silt from washing into the lagoon.   This may cause the shoreline to be unsightly and organic decomposition may result in an unfavorable odor. 

Revegetation Plan

We are currently working on the replanting plans.  Specifics will be available soon, however, native species will be used to revegetate the banks and, where possible, the revegetation plans will adhere to the historic planting plans.