2015 Wingra Watershed Plan

Cover

Public Summary of the June 2015 draft final

“Lake Wingra Watershed Management Plan”

Prepared by Jim Baumann – June 25, 2015

 In 2009, the Friends of Lake Wingra (FoLW) published Lake Wingra: A Vision of the Future that stated four main goals for Lake Wingra:

  • Clean, clear water
  • Restored spring flow
  • Abundant native plants and animals
  • Stewardship and enjoyment

 

To achieve and sustain these goals, FoLW realized that management of the 3,500 acre urban Lake Wingra watershed was vital.   To that end, FoLW worked with the Madison City Council and City of Madison Engineering (City Engineering) to secure funding for development of the Lake Wingra Watershed Management Plan. City Engineering hired Strand Associates to conduct watershed model analyses and to prepare the watershed plan under the direction of a steering committee.

In June 2015, the 243-page draft final plan was released for public review and comment.  The full document can be found at the following link on the City of Madison website: Wingra Watershed Plan – Strand Associates

 

Realizing that a person living in the watershed would find the length of the plan daunting and the format associated with state storm water permit difficult to understand, FoLW prepared this brief summary. This summary is divided into four parts:

  • General comments
  • Chlorides
  • Infiltration
  • Phosphorus

Fig 1.01-1

General Comments

  1.  The watershed plan identifies a proposed set of management measures or practices that will achieve the goals for each of the three focus areas: chlorides, infiltration and phosphorus.
  2.  The watershed plan does not fully identify how and when these management measures of practices will be implemented. Instead it calls for the formation of Catalyst Teams for each area of need (see Section 5) to meet in late-2015 to develop action plans for the near-term implementation. The topics addressed by the Catalyst Teams vary greatly by the area of need and are discussed briefly by each of the three need areas.
  3.  Implementation of the watershed plan can be funded in part through existing city programs, such as through its Storm Water Utility. However, some of the implementation will require additional funding from the city, Dane County, state or others.
  4. There is no specific schedule or deadline for implementation. Many of the management practices can be implemented in the next few years but many will need to be implemented over a 10, 15 or 20-year period.
  5. Implementation of the phosphorus component of the plan will assist the city in complying with its state-issued storm water discharge permit and with its portion of the total maximum daily load plans for the Rock River Basin.
  6.  The watershed plan will be presented to the Madison Commission on the Environment and the Board of Public Works. It will be offered for approval to the City Council. It may also be presented to the Dane County Lake and Watershed Commission and groups associated with improving the quality of the Yahara Lakes.
  7.  The project steering committee will continue to maintain continuity between development and implementation of the plan.

Chlorides

 Need

Chloride concentrations continue to increase in Lake Wingra. Concentrations were low in the 1960s when the City of Madison started to use salt as a street de-icer and have increased since then to an average concentration of 115 mg/L in 2012.

[Note: Odana Pond, the other body of water in the watershed, has seasonal concentrations of more than 2000 mg/L; exceeding the Wisconsin water quality standards chronic toxicity criterion of 395 mg/L.]

Goal

The 2009 Lake Wingra: A Vision for the Future recommended a goal of 40 mg/L; about half the concentration in 2008.

Sources of Chlorides

De-icers, such as road salt, are the primary source of chlorides in Lake Wingra. The chlorides may enter with surface runoff through the storm sewer system or be discharged from springs where salt has seeped into the groundwater.

The largest contributors of salt in the Lake Wingra watershed are shown in the table below summarized in the figure below.

Fig 2.03-5

 

Salt application rates vary greatly and there are no established city or state maximum application rates. Commercial application rates average at least 20 pounds per 1,000 square feet; much higher than 3 pounds per 1,000 square feet recommended in Minnesota. The frequency of salt use also varies.

Management Approach

 To achieve the chloride goal, salt use would need to be reduced by 50 to 60 percent. A short-term alternative is a 40 percent reduction by commercial applicators and a 20 percent reduction by municipal applicators.

Table 2.08-1 of the plan provides the following list of management measures, their feasibility and their potential effectiveness.  Please note that the potential effectiveness was assigned by the consultant and Friends of Lake Wingra is more hopeful of the effectiveness of some of these measures.

 

Management Measure Feasibility Potential Effectiveness
Implement a Certification Program for Commercial Applicators High Low
Provide Sample Contracts for Winter Pavement Maintenance on Web Site and with Certification High Low
Require Certification for Government Snow Removal Contractors High Low
Establish Maximum Salt Guidelines Medium Low
Establish Maximum Salt Application rates by Ordinance Low Medium
Expand the Practice of Anti-icing High Medium
Reduce the Number of Applications per Snow Event Medium Medium
Reduce the Salt Route Mileage Medium High
Investigate Alternative De-icers Medium Medium

 

Infiltration

 Need

Springs provide unique habitat for plants and animals. The number of springs and the amount of water flowing from springs to Lake Wingra has decreased with urban development of the watershed. Rainwater that previously infiltrated and fed the springs is now intercepted by rooftops and streets and conveyed to the lake through the storm sewer system.

Goal

A short-term and a long-term goal are defined as follows:

  •  Short-term: Recover 10 percent of the lost infiltration resulting from development
  • Long-term: Recover 25 percent of the lost infiltration resulting from development

Fig 3.02-4

While the chloride and phosphorus areas of need are based on the surface water watershed, the groundwater recharge area has a different boundary; extending south of Dunn’s Marsh but not extending west of Odana Pond.

Management Measures

Table 3.03-11 of the draft plan lists a variety of management measures necessary to achieve the infiltration goals. Many of these management measures also control phosphorus and are included in the section 4 of the plan. The additional cost (20-year present worth) over the base phosphorus control measures is about $1.7 million. In general the management measures include:

  •  Structural management practices installed on public property
  •  Downspout redirection, rain barrel and rain gardens on residential properties **
  •  Rain gardens on commercial properties **
  •  Terrace rain gardens on public rights of way **
  •  4 acres of porous pavement **
  •  Monroe Street Green Street **

** = means same as for phosphorus.

 

Table 3.06-1 lists potential management measures as well as their feasibility and priority as follows:

Management Measure

Feasibility Implementation Priority
Implement Dedicated Funding for City Projects High High
Expansion of city’s 1,000 Rain Gardens Initiative High High
Expansion of City’s Terrace Rain Garden Program High High
Creation of city Porous Pavement Initiative High High

 

Phosphorus

 Need

Phosphorus is considered the most important nutrient in controlling algae and nuisance aquatic weeds in Lake Wingra.

Goal

The draft final watershed plan expresses both short-term and long-term goals:

Short-term:

About a 20% reduction from existing conditions (actually expressed as a 50% reduction compared to “no pollutant reduction controls in place” condition.

Long-term:

About a 70% reduction from existing conditions (actually expressed as an 80% reduction compared to “no pollutant reduction controls in place” condition. This level of phosphorus reduction is needed to reach the wasteload allocation requirements of the Rock River total maximum daily load plan.

[Note: The “no pollutant reduction controls in place” is used as a baseline for state-issued WPDES storm water discharge permits. As shown in Table 4.03-2, the existing conditions may vary greatly from this baseline. For example, in the western portion of the watershed where a number of storm water basins are in place and with Odana Pond retaining some of the phosphorus, the existing phosphorus load (mass) is about half of the “no pollutant reduction controls in place” load. In contrast in much of the eastern portion of the watershed, the existing and “no pollutant reduction controls in place” loads are similar.]

Figs 4.02-3

Fig 4.02-4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sources

Much of the phosphorus reaches the lake in the fall when leaves are in the streets and during the spring. Tree leaves, pollen and buds are not only a major source of phosphorus, but are the primary source of phosphorus in a dissolved or soluble form. Soluble phosphorus is readily available to algae and also is difficult to control in storm water basins.

Other sources of phosphorus include windblown soil, pet wastes, eroding soils (e.g. stream banks, construction sites), lawns and lawn clippings. Storm water runoff readily carries the phosphorus into city storm sewers and to Lake Wingra. Over time, lawns will become less of a source as the number of years no phosphate lawn fertilizers are used.

Management Practices

Core Base Management Practices

Table 4.03-7 of the plan contains a base list of management practices at a cost of $12,700,000 (20-year present worth) including:

  •  Storm water wet ponds, bioswales and bioretention basins constructed on public property.
  •  Terrace rain gardens built on city right-of-way ##
  •  Downspout redirection, rain barrels and rain gardens on private residential property ##
  •  Rain gardens on commercial property ##
  •  4 acres of porous pavement ##
  •  Monroe Street Green Street ##

## = same as for infiltration

 

On a cost per pound of phosphorus controlled, the structural storm water practices tend to be the lowest cost while terrace and commercial property rain gardens is the highest cost. While the storm water practices on public property may be funded through the city’s storm water utility, it has not been determined who will bear the costs for practices on private properties.

Alternatives for Additional Management Practices

The management practices listed above are not sufficient to meet the phosphorus reduction goals. Table 4.04-1 lists alternatives for additional management practices to meet the goals. These alternatives range widely and include:

  •  Better enforcement of the construction site erosion control ordinance (especially on re-development projects within the watershed). This alternative would control as much phosphorus as the core management practices listed above. The cost per pound of phosphorus controlled is lower than any of the management practices listed above.
  •  Better pet waste ordinance enforcement.
  •  Modified (improved) leaf collection to emphasize removing leaves from the streets. On a cost per pound of phosphorus controlled, this is one of the lowest cost alternatives.
  •           * City Engineering has committed to continuing the improved leaf collection pilot project in the fall of 2015  *
  •  Improved street sweeping.
  • Alum addition to Manitou and Marion Dunn Ponds. This alternative would also control more phosphorus than the core management practices listed above and at a lower cost. Alum addition is used in Florida and other states.
  •  Wetland vegetation harvesting produces a substantial phosphorus reduction and has the lowest cost per pound.
  •  Stream bank restoration at Thoreau School and along Cherokee Drive. While the phosphorous reductions are moderate, the cost per pound is less than many of the management practices listed above. State funding has been provided for the Thoreau School site.
  •  Additional storm water management practices on public property, such as a wet pond in Wingra Park.

 

Table 4.06 of the draft plan groups the management practices and offers opinions on feasibility and implementation priority as follows:

 

Management Measure Feasibility Priority
Implement Dedicated Funding for City Projects High High
Modified City Leaf Collection Methods High High
Modified Street Sweeping Methods/Schedule Medium Medium
Miscellaneous City actions (e.g. ordinance enforcement) Medium Low

 

What You Can Do to Help

Friends of Lake Wingra is actively working to make sure that this plan is implemented so we can start to see improvements in Lake Wingra and the Wingra Watershed.  We are collaborating with the City of Madison and other partners on this process.  The next presentation of the Watershed plan by Strand Associates will be on July 14 from 630-830 pm in the Auditorium at the UW-Arboretum.  Invitations have been sent out to the Neighborhood Associations within the Wingra Watershed, any who have an interest in the health of Lake Wingra and the watershed are welcome.  Please join us in supporting the implementation of this Watershed plan by letting your alder person know you support implementation.  Stay tuned to our website, emails, newsletters and Facebook page for future updates on how you can become involved.