By Sage Passi
Photo credit: Maplewood Historical Society
It’s been a long time since swimming has been possible in Wakefield Lake. Stories of summers spent swimming in the lake are often described by people who grew up around the lake years ago. I talked to Sharron Olson, a long-time resident of the Wakefield Lake neighborhood and steward, and asked her to tell me what she remembers about the lake when she was young. A few years ago she helped Cross Lutheran Church across from the lake install a large rain garden to capture stormwater from their parking lot. Her memories say a lot about why she was drawn to helping Wakefield Lake.
She recounted her childhood and teenage years at the lake:
“When I grew up near the lake, there was a beach with a life guard and we went there all the time to swim. It was a place where all the kids gathered. It was wonderful place to get together and we loved going there. We’d catch crayfish off the dock. As teenagers we hung out there in the late fifties.”
Urban Growth Takes a Toll
The impacts of urbanization have affected many of our lakes in the metro area over time. Senior Water Resources Engineer, Erin Anderson Wenz (Barr Engineering), who works closely with the Watershed District on many of our projects says,
“We have greatly changed the watersheds that drain to our urban lakes. In doing so, we have greatly increased our need to implement projects that will, to some degree, mimic our watershed’s natural hydrology. With this work however, comes the need to balance our expectations about how long it will take, and how much effort will be needed to reach our goals. There is a lot of work involved in undoing what we have done over the last 100 years.”
While those “memorable” swimming conditions are unlikely to be recreated, the good news is that efforts have been underway for some time and are destined to continue to improve the water quality in Wakefield Lake.
Through our permit program, capital improvements, Maplewood street rain garden projects and other BMPs we are making headway toward our goals. A map and a chart at the end of this article document this progress. A new project on the horizon being implemented this summer promises to help make some significant headway in addressing phosphorus issues caused by run-off.
Maplewood has a long range vision of “reinventing” Wakefield Park around the lake and reinvigorating its vitality through a focus on family activities, public art and landscape design. Ramsey-Washington Metro Watershed District met with city staff in the Park’s Master Planning process in 2015 to discuss ways to augment those future city efforts by reducing the effects of stormwater run-off on the water quality of the lake.
The District worked with the Minnesota Pollution Control Agency (MPCA) to perform a Total Maximum Daily Load (TMDL) study of the lake. Wakefield Lake is currently on the MPCA’s impaired list for excess phosphorus.
|Total Phosphorus in Wakefield Lake 1984-2013|
Through the Wakefield Lake TMDL process, implementation activities have been identified which include partnerships with the City of Maplewood to install BMPs in the watershed to reduce phosphorus levels to benefit the lake.
Field Test Using Spent Lime Has Positive Results For Stormwater
|Two views of the Watershed District’s spent lime test site near Wakefield Lake|
In the past three years RWMWD has been researching, monitoring and field testing the use of spent lime for stormwater quality treatment. Spent lime consists of calcium and carbonate and is a waste by-product of the drinking water treatment process that has properties that allow it to bind with particulate and dissolved phosphorus.
|Calcium from spent lime in our test area helps remove phosphorus from stormwater before it enters Wakefield Lake.|
When water containing phosphorus (both dissolved and particulate) contacts the lime material, calcium from the lime binds with the phosphorus and forms calcium phosphate which is a solid material and does not dissolve in the storm water, thus remaining within the treatment system. Only a small contact time (5-15 minutes) is required for the chemical reaction to bind phosphorus to the calcium in the lime, meaning a fairly small BMP footprint is required to treat a significant volume of water. Typically lime is disposed of via agricultural land applications. With its significant phosphorus binding capacity and a long lifespan (e.g. 100 plus years) this makes the use of spent lime a very cost-effective BMP.
Three years of monitoring the test spent lime system near Wakefield Lake have shown positive results for the removal of both total and dissolved phosphorus. Total phosphorus removal is 60% and total dissolved phosphorus removal is 70% in this test situation.
Spent Lime Filtration Project will be Installed this Summer
The District searched for a site near Wakefield Lake with a storm water infiltration basin that could be retrofitted to install a spent lime system. A location was secured and in the fall of 2015 the District submitted a grant proposal for funding to implement a larger scale project that could treat a substantial amount of stormwater using this experimental BMP method.
|The District found this proposed site for the spent lime filtration system.|
|The District is evaluating the best location at the Kennard and Frost intersection for the Spent Lime Treatment System. The initial design is pictured above.|
This system, integrated into a stormwater basin that will be retrofitted, is designed to achieve an annual Total Phosphorus removal of 45 pounds (24.4 lbs. during the growing season, June through September), which is nearly 50% of the needed phosphorus external load reductions to Wakefield Lake as identified in the TMDL. Construction will occur between July and November of 2016.
Stakeholder involvement and communication is a central part of this project, because it is surrounded by residential properties. Information has been distributed to the neighborhood and feedback has been solicited regarding the treatment site and aesthetics of the design. The city is considering implementing a community garden or orchard area adjacent to the filtration system that the community could use. This could be a good opportunity for community engagement and a way to demonstrate a new technology for stormwater treatment that will allow others to learn more about this new cost-effective technique.
|The District is evaluating the best location at the Kennard and Frost intersection for the Spent Lime Treatment System. This initial design incorporates an orchard on the side.|
History of the Water Quality in Wakefield Lake
The Ramsey County Department of Public Works staff samples the water quality of Wakefield Lake about seven times per year on average, between the months of May and September. The table below summarizes the most recent ten-year averages of nutrient related water quality parameters for Wakefield Lake relative to MPCA standards.
|Wakefield Lake historic nutrient related water quality parameters|
Sediment cores were taken from the lake in 2009 to assess the lake’s internal phosphorus loading potential from sediment release. The sediment cores were also used to evaluate the water quality in the lake before European settlement.
|A St. Croix Watershed Research Station scientist takes a sediment
core in Wakefield Lake to collect fossilized diatoms that can help
tell the story of its water quality over time.
By analyzing the types of diatom fossils in the core, scientists from the St. Croix Watershed Research Station were able to tell that, since the time of European settlement, Wakefield Lake has changed from having a moderate level of nutrients (mesotrophic) to having a high level of nutrient (eutrophic) that promote significant algal growth.
|Increased phosphorus in Wakefield Lake has contributed to its problem with algae blooms.|
What Drainage Areas Have the Most Effect on Wakefield Lake?
Extensive P8 and in-lake water quality modeling have been done throughout the Wakefield watershed and the lake itself to determine where the most significant sources of phosphorus are, how that phosphorus moves across the lake’s watershed and how both external (watershed) and internal phosphorus loads combine to affect the lake’s water quality. Analysis has revealed that stormwater entering from the northeast and northwest sides of the lake have the most influence on the lake’s water quality. Stormwater entering from the Larpenteur storm sewer from the southeast has the least. This is because the stormwater from the Larpenteur storm sewer mostly travels directly to the lake’s outlet on the west side of the lake.
|Drainage districts in the Wakefield Lake Subwatershed|
What Progress are We Making?
The Wakefield TMDL section of the RWMWD TMDL Report (Draft, Barr Engineering, 2016) calls for a 52 lbs. per growing season reduction in phosphorus through projects implemented after 2004. Progress has begun toward this goal and will continue through implementation of District capital improvement and cost share and permit programs. The level shown on the “Phosphorus Reduction” bar in Figure 2.8-8 indicates the District’s progress toward the Wakefield Lake phosphorus reduction goal as of December 31, 2015 as a result of District efforts.
|Wakefield Lake Sub-watershed Permit, Cost-share, Capital Improvement and other
District projects through December 31, 2015
While Wakefield Lake will never be the same as it was for residents like Sharron Olson, its water quality improvement trends make us hopeful that we can moderate the impacts that have gradually challenged the lake over the last sixty years. Wakefield Lake is an amenity for the neighborhood, provides habitat for birds, fish, insects and animals. It has a DNR Fishing-in-the-Neighborhood program for kids and is a great place for a picnic, wildlife-viewing and relaxing! We all look forward to seeing its water quality improve.
|Wakefield in the 1960’s
Photo credit: Maplewood Historical Society
Information for this article taken from the 2016 Ramsey-Washington Metro Watershed
District Draft Management Plan.