Rimrock Road Pond Retrofit for Improved Water Quality

Last Updated: 03/13/2019

Rimrock Road Pond Retrofit for Improved Water Quality

The City of Madison is planning to enhance the stormwater management system that treats a 136 acre watershed that is located on the east side of Rimrock Road between E Badger Road and Moorland Road. Eventually this water flows into Lake Monona.

The City proposes to update the stormwater system from what looks like a ditch with a concrete bottom, to a pond that permanently holds water. By creating a pond that permanently holds water, the system will be able to remove more sediment and nutrients from the stormwater before it reaches Lake Monona.

Based on the preliminary design, the project will result in annual reductions of the following to Lake Monona:

  • 12,800 lb of particulate solids
  • 29 lb of phosphorus
  • 15,000 lb of algae
Rimrock Road Pond Project Area and Watershed
Rimrock Road Pond Retrofit Location & Watershed Area

Public Input Meeting

A public input meeting was held at the Badger Rock Neighborhood Center (501 E. Badger Road) on January 16, 2019 from 6:30 pm – 8:00 pm

The presentation can be viewed here: Public Input Meeting 01-16-2019

Common Concerns

  • Increase in mosquitos: By upgrading a dry pond that is often swampy and has puddles of water, to a wet pond, that always has standing water, the City is better able to manage mosquito populations. This is because mosquitos can reproduce in any size body of water, from a puddle to a pond. However, in a puddle, the mosquito have very few predators. In order to control mosquito populations in stormwater detention ponds, the Department of Public Health stocks the ponds with minnows each summer so that the minnows can feed of the mosquito larva and stymie the population before they hatch.
  • Risk of drowning: The ponds are designed to mitigate the risk of drowning. There is a 10 foot safety shelf around the perimeter of the stormwater detention pond to reduce the risk of someone falling into the pond. Native, wetland plants in the safety shelf combined with tall, native prairie plants on the slopes discourage wading and swimming. This 10-20 foot "buffer" provides pollinator habitat and improves the effectives of the pond. Additionally, there are ~250 ponds within neighborhoods in the City, all designed to help improve the water quality in the lakes.
  • Risk of flooding: At the public meeting, the City was notified of the near-flooding experiences of a current pond neighbor. The City designs system upgrades to accommodate the same amount of stormwater, or more, to ensure that new projects do not cause flooding. Knowing about areas that flood can help the City to design better solutions that can make communities more flood resilient. Please report any flooding experienced at: www.cityofmadison.com/reportflooding

Proposed Schedule

Preliminary Design - 2018

Gather Public Input - Winter 2018/2019

Design - Spring/Summer 2019

Build - Late Summer/Late Fall 2019