By Sage Passi
|The annual District Tour stops at Keller Creek to view the progress of
the restoration and the renovation of the portages next to the weir.
Here are a few highlights from our stops!
Kohlman Lake – Where the Action Is
|The shoreline of Kohlman Lake|
Kohlman Lake is never far from our thoughts. A lot of the work we do as a Watershed District has focused on this lake over the years. BMP projects upstream, carp seining, aquatic plant management and alum treatment are some of the key management tools the District has been implementing to improve water quality for this lake over the years.
As we circled around to the backyard of Anita and Scott Jader’s lakeshore property, our eyes settled on a configuration of pole contraptions extending out of the water near the shore. “Box nets”, announced Bill Bartodziej, our biologist. Then Scott chimed in with, “fifty-nine carp caught this morning.”
|Box net traps set up at Kohlman Lake|
These box-shaped nets are baited with dried cracked corn to train carp to aggregate in the nets. This process is being used as on-going management tool for reducing carp biomass in the Keller-Gervais-Kohlman system of lakes. Carp feed at night and the nets are restocked with corn each day. When most of the corn is consumed each night for a couple of weeks, Carp Solutions, LLC, the team that has been hired to help us with on-going carp control, can feel confident that they will likely trap a large enough number of carp to return and lower the nets. The team arrives at the lake about four in the morning, sneak up to the traps, pull the ropes to lower the weights which triggers the sides of the nets to pull up, trapping the carp. Then the carp are counted, their lengths measured and then removed and taken to a compost site at Ramsey County Corrections.
|Aquatic plant harvester on Kohlman Lake (left) and Coontail “harvested” from Kohlman Lake (right).|
Next Bill shifted our attention to the middle of the lake where an aquatic plant harvester was cutting swaths through the thick mats of aquatic plants that rest on the surface of Kohlman Lake. This harvesting has been going on for the past two months. Mechanical challenges have extended the length of this harvesting. “The most troublesome plant this year has been the native one called “coontail,” acknowledged Bill.
“Residents on the lake are saying that this is the worst year ever, in terms of “weed” or aquatic plant growth. This plant forms surface mats that are quickly colonized by filamentous algae. These big floating mats can cause problems for fisherman and boaters. At one point this summer around fifty percent of the lake surface area was covered with coontail and filamentous algae.”
Coontail doesn’t have roots so it takes nutrients out of the water column. The improvement in water quality, especially water transparency over the years, is likely causing the increase in cover of the coontail/algae mats. Bill explained that this is a really common response seen in shallow urban lakes.
Bill said that a recent transparency reading in Kohlman was 7.5 feet, which is very good for a shallow lake in the Twin Cities metro area.
“With the alum treatment, carp control, and watershed projects like Maplewood Mall, we have seen an increase in water clarity over the last few years. The down-side is that aquatic plants are now growing at troublesome levels.”
Over 225,000 pounds (wet weight) of plant material was harvested and removed from the lake this summer. Through analyzing the plant tissue for phosphorus (P), Bill estimates that around 32 pounds of phosphorus has been removed from the lake system. Factoring in the costs of harvesting, that amounts to a cost of an estimated $500 per pound of phosphorus removed. Compared to the cost of commonly used watershed BMPS, like rain gardens, this is very economical. But there are other considerations to keep in mind as well, so this winter the District will be studying the phosphorus budget of Kohlman Lake to figure out if phosphorus removal from harvesting is substantial in the big scheme of things. If it is, then he says the District may want to consider harvesting as an in-lake phosphorus management tool, in addition to a way to improve recreation and aesthetics. More data and analysis from this study will be forthcoming over the winter months.
Postal Credit Union Pond – A lesson about flood control and Atlas 14
|Brad Lindeman, District Engineer, shares history about
the Postal Credit Union Pond in North St. Paul.
Our two guides for this stop on our tour were Brad Lindeman, District Engineer, and Brandon Barnes, a civil engineer consultant who also works for Barr Engineering.
|Brandon Barnes, Barr Engineer, explains the
application of the Atlas 14 model
at PCU Pond.
Brad shared the history of this large pond and the reasons why it was built. The Postal Credit Union Pond (formerly known as Target Pond) is a flood protection and stormwater treatment basin in North St. Paul that was completed back in 1995.
Located on Watershed District and North St. Paul public lands, this nine-acre site holds back water from Kohlman Creek (County Ditch 18) to protect White Bear Avenue from flooding, and also serves as a wildlife park amenity to area residents.
Without the project, District hydrologic models estimated that White Bear Avenue would be overtopped by flood waters, resulting in street and utility damage and flooding damage to a number of adjacent businesses. The project provided needed additional storage volume within an existing basin.
Brandon explained that the District is currently reviewing the results of an updated hydrologic/hydraulic model called Atlas 14 and identifying flood-prone areas within each city. The new Atlas 14 model factors in much more data than previous models and it updates under-projected levels of rainfall and depths, given the magnitude of recent storms.
|PCU Pond protects White Bear Avenue
and adjacent businesses from flooding.
For more information, you can read an earlier article “What is Atlas 14?”
Overlooking the pond as we listened to Brad and Brandon, many questions surfaced from the group, affirming that this location was a good choice for the group to visualize applications of the Atlas 14 tool. The discussion looked at past and future land use and began to imagine the projected impacts suggested by the new data.
|Aerial view of PCU Pond|
Brandon provided a draft map that reflects potential changes to the flood levels in PCU Pond using data from the new Atlas 14 model. We started to imagine possible impacts on surrounding areas if we factored in updated Atlas 14 calculations. He told us that staff will be reviewing each of the areas of concern in the District and identifying and prioritizing areas that should be considered for future feasibility studies and improvement projects to reduce the risk of flooding. These areas will be prioritized based on several criteria including comments provided by the cities, magnitude of flooding, and number of impacted structures, as well as other factors.
This stop provided a lot of pause for thought and reflection!
Keller Creek – Reflections on the Restoration
|Dana Larsen-Ramsay inspects the summer’s growth of emergent plants
that were planted along Keller Creek’s shoreline by the CAC and LEAP Teams.
We took a break from pondering heavy subjects like climate change and flooding and stopped to enjoy a box supper in one of the Golf View Park pavilions in Keller Park, just off Highway 61 in Maplewood.
After our break, we headed down the hill to learn more about the Keller Creek restoration in progress. We stopped to admire the June emergent planting done by CAC and LEAP team members along the creek’s edge. Healthy stands of arrowhead, bulrush and various sedges adorn the shoreline.
|Katie Keefer, CAC member, follows along Keller Creek during the tour.|
We then strolled along the prairie and wet meadow plantings completed by hundreds of students with help from District staff, interns and Ramsey County Master Gardeners.
Bill Bartodziej described the process that has been unfolding in this restoration project this year and what will be coming next. This is a four-year project and year one has just been completed.
We converged at one of the newly renovated portages near the weir.
Everyone was impressed and wished we had a canoe with us to try it out!
Citizen Advisory Commission member, Dana Larsen-Ramsay, shared some ideas about the CAC’s vision of a Water Trail project to encourage the community to explore the connected trail of water bodies in the Phalen Chain of Lakes that includes this creek. We eyed the west bank of the creek and Bill pointed out the test plots for next year’s phase of the restoration. We look forward to coming back again next year to see how it is progressing.
|Reflections on Keller Creek after one season of restoration.|
Rosetown American Legion – Retrofitting for Clean Water
We climbed back up the hill to the bus and headed to our next stop at the Rosetown American Legion parking lot where Paige Ahlborg, Watershed Project Manager, and Matt Kumka outlined the process of capturing stormwater from this commercial site. This is one of three commercial site retrofit projects constructed this year and scheduled to be planted this fall. The stop also highlighted retrofit efforts currently underway at schools, churches, and several other commercial sites around the District. Construction at these sites is proposed to begin summer of 2016.
|A new (and yet-unplanted) rain garden
at the Rosetown American Legion.
Bennett Lake – New Kid on the Block
|Bennett Lake in Roseville.|
The tour then drove to the western side of our Watershed District where a discussion awaited us about this latest addition to our watershed and what may unfold for future projects in the Bennett Lake sub-watershed. Erin Anderson-Wenz from Barr Engineering updated the group on the water quality and Total Maximum Daily Load (TMDL) status for Bennett Lake and the other lakes in RWMWD. Stay tuned for more information on Bennett as the story unfolds.
Those will have to be the subject for a summer tour down the road!
But as for tonight, what a delightful evening we’ve had!