Pamela Park Wetland Restoration Project
Park History and Use
Pamela Park is a 64-acre city park located within Edina east of Highway 100 and north of the Crosstown Highway, which contains Pamela Lake, an 18.4-acre wetland designated as a DNR Protected Wetland. It is part of the Minnehaha Creek Watershed District (MCWD) drainage area. In addition to the wetlands, the city park contains tennis courts, soccer, hockey and softball fields and is a popular neighborhood place to play and picnic.
The Challenge: Pamela Park's Wetlands Have Been Damaged by Human Activity
Historically, existing wetland areas within the park were part of a much larger wetland complex that drained into Minnehaha Creek. Over the years, development of the city park and adjacent residential areas has resulted in substantial filling of wetland areas and sediment deposit from municipal storm sewers.
More than 500 acres of fully developed residential areas currently drain through Pamela Park discharging into Minnehaha Creek. Nutrient and sediment loads flowing into the lake from urban storm water runoff have affected the lake's water quality and reduced water depths. This runoff contains sediments, phosphorous and other pollutants that hurt water quality.
Neighborhood residents have expressed concerns about declining water quality conditions and general degradation of Pamela Lake. They also have observed th at the variety of wildlife species and plant diversity in and around the lake has diminished over the years.
Shallow water levels in Pamela Lake have contributed to dense weed growth and significant reductions in fish population. The average depth of the lake is approximately two-feet, with a maximum depth of four-feet in the center. Sediment deltas (deposits of dirt and rock) have also formed at the outlets from the two major storm sewers flowing into the south end of the lake.
The Solution: A Two-Part Plan to Restore Pamela Lake With a Partnership Between the City of Edina and the MCWD
Over the past few years, the City of Edina, concerned neighborhood citizens and MCWD have met to discuss approaches to cleaning up Pamela Lake. The overall goal is to restore Pamela Lake, improve water quality conditions, and reduce external phosphorus and sediment loads to the lake and downstream to Minnehaha Creek.
A collaborative partnership was formed between the City of Edina and MCWD to design, fund and implement the lake cleanup. MCWD is providing the financial and technical support and the City of Edina will manage the project on a short-term and long-term basis.
By contract through the MCWD, Wenck Engineering has developed an overall water quality improvement plan while Barr Engineering prepared the original concept plan for the city and has designed an environmental landscaping plan. The Pamela Lake Association has been instrumental in supporting improvements to the park and providing neighborhood input to the planning process.
Excavation of Pamela Lake and Storm Water Basins
During the winter of 2000-2001:
- Accumulated sediment in Pamela Lake will be dredged out, including the sediment accumulated near the two major storm sewer outlets. The excavation of Pamela Lake will increase the average depth from 2 to 3.5 feet and create about 1.2 acres of deep-water habitat.
- Sediment-settling basins will be constructed at the two major storm sewer outlets to the lake/wetland at the southern end. These basins will capture and settle pollutants from the storm sewer runoff before it drains into the wetland, keeping pollutants from entering Pamela Lake and downstream Minnehaha Creek. The sediment basins will treat storm water runoff from 129 acres.
- The storm water system will be inspected and routine maintenance will be performed as necessary to ensure proper operation. Periodic clean-out of accumulated sediment from the ponds will also be done to maintain their effectiveness in removing nutrients, sediments, and other pollutants.
North End Pond Construction
- Three wetland-settling ponds were built in the northern part of the park, starting in the spring of 2001 with completion planned for summer 2001. The ponds are naturally landscaped with native trees, shrubs and prairie flowers and grasses. Wetland settling ponds are an environmentally friendly, gravity-based method of cleaning surface water. Settling ponds receive storm water runoff from storm water drains. Phosphorous clings to the grit in the runoff and settles to the bottom of the ponds.
- Nuisance algae blooms in Pamela Lake are caused by excessive phosphorous. Most of the phosphorous originates in the local watershed -- a main source being leaves and lawn clippings -- and is carried by runoff. Other sources of pollution, like oils, pesticides and sediments, are also carried in runoff from the neighborhoods.
- The three upland ponds (Ponds 1, 2, and 3) will treat runoff from 297 acres. The 297 acres include 242 acres that currently discharge directly into Minnehaha Creek and 55 acres that currently drain into the wetland downstream of Pamela Lake.
- A new nature trail also will be added. The trail will loop around Ponds 2 and 3 and the western side of the lake, offering a quiet pedestrian connection between W. 58th Street and W. 62nd Street and a chance to view the ponds and wildlife.
- The City of Edina will implement various programs aimed at reducing nutrient and sediment discharges to Pamela Lake, providing further protection of the wetland. These programs include developing management plans for snow storage activities currently taking place within the park, reducing phosphorus fertilizer, and managing geese, along with the continued sweeping of city streets within the tributary drainage area.
Pamela Park's New Wetland Ponds: Landscaped Beauty Combines with Settling Action To Clean Up Algae-Producing Phosphorous
Called wetland ponds, settling ponds, or storm water detention ponds, these products of environmental engineering work by capturing contaminated runoff before it enters a larger water body. This allows phosphorous (the main culprit in algae blooms and degraded water quality) to settle at a pond's bottom, becoming food for wetland plants.
Pamela Park's new ponds are a major component of the comprehensive plan developed by the partnership of the City of Edina, residents of the Pamela Lake Association and MCWD to address water quality and wildlife habitat concerns for Pamela Lake Park.