Above the Falls: Natural area scoping report
Synopsis of key findings and recommendations
St. Anthony Parkway and Mississippi River Park
This area is basically a natural riparian buffer on the east bank of the river, just south of the Camden Bridge. The best protection of the shoreline/banks was the presence of really large cottonwoods, which were still clinging to life on the lower banks. A few root wads were left holding, too. Gathered around each root wad or cottonwood tree were communities of natives, for example, prairie cord grass, Carex sedge species, wild geranium, dogbane, milkweed species, goldenrod species, Solomons seal, stonecrop, and wild rye. Where the sedges and cord grass occurred, the undercut toe formed a ledge due to the fibrous roots of the plants beneficial for fish habitat. Otherwise, the riverbank appeared to be eroding quite rapidly, and, unfortunately, cottonwood regeneration (young seedlings and saplings) was almost non-existent here, and throughout the entire ATF corridor, which does not bode well for the future of the riverbanks. The upland banks are dominated by buckthorn and Tartarian honeysuckle, which we recommend be removed and replaced with native trees and shrubs.
Marshall Terrace and Heron Islands
This is primarily a recreational park, but there is also a length of natural shoreline buffer that could be improved by planting to increase diversity. Just offshore on the north side of the park, across from the Xcel Energy plant, there are two islands, one of which contains several very tall cottonwood trees ideal for nesting birds. After a nearby rookery was destroyed three years ago by a tornado, blue herons established a new one on this very island. The DNR has counted upwards of 40 nests in this rookery. Unfortunately, this island is experiencing some pretty severe erosion. Many of the largest trees are actually rooted on the shore of the island, which has much exposed bare soil and little understory vegetation to anchor it.
Edgewater Park
On the east bank, near the foot of the new Lowry Bridge, is the site of this little park. Recently, a prairie garden and infiltration swale were installed at Edgewater Park. The prairie garden was in fair condition, but has been quite badly invaded by spotted knapweed (an invasive, exotic forb), which will eventually come to dominate the site if unchecked. This prairie garden should be burned, since fire is vital for the good health of a prairie. Unfortunately, fire alone will not control knapweed; it needs to be hand pulled or spot treated. Local volunteer stewards could be utilized to help control the knapweed and maintain the prairie garden.
Gluek Park
A typical community park, this small site was dominated by turf, linear gardens, and planted trees, and it also contained a picnic shelter and paved trails. There was a huge mulberry tree on the southern end of the site. The riverbank was considerably riprapped at the toe, and turfed upslope, with an abundant growth of crown vetch (an invasive, exotic forb). The riverbank slope could be planted with native shrubs, which would be easier to maintain than mowing turf. Also, willow stakes could be installed at the toe, into the riprap, to help stabilize and beautify the slope.
Ole Olson Park
This site offers some exciting restoration potential. For a rather small site, it contains a large diversity of landscapes: shoreline, woodland terraces, and grassland slopes. Restoration has already begun here, with shoreline restoration, slope stabilization, and prairie reconstruction on the riverbank. We recommend continuing these practices and expanding them to the entire park area. Currently, the rest of the park is in pretty rough shape, being dominated by a host of invasive exotics such as smooth brome grass, Siberian elm, and Russian thistle. With some foresight and hard work, this situation could be turned around, though. One could envision a day when the shoreline is stable and filled with native willows, sedges, and transitional plants, the slopes are blanketed in prairie wildflowers and grasses, and the terraces are home to scattered, majestic bur oaks and all nurtured and enjoyed by local residents. What a grand future that would be!
22nd Avenue Raingarden
Recently a raingarden has been installed at 22nd Avenue, across from the MPRB headquarters. This raingarden looked good, with many native species flourishing throughout, but there were some patches of non-native plants and several scattered Siberian elm seedlings found. Burning this raingarden would be beneficial it would help control invading woody plants and also invigorate the native graminoids and forbs.
Sheridan Memorial Park
This site gives the impression that it was once a former industrial site that has been recently converted into a city park. The soil was very compacted, with turf grass and scattered small, planted trees (hawthorn, crab apple, pines, maples, cottonwoods). There was a large parking lot near a warehouse that sloped towards the river, sending stormwater into a poorly drained area of the park. Perhaps the best use for this park is to continue its present usage, since it functions as a buffer to the river, rather than implementing a full-blown native restoration here. We recommend creating raingardens to capture the stormwater runoff from the parking lot, though.
17th Avenue Overlook
The lower banks had been restored to native prairie and were quite nice. Some of the shoreline had a dense growth of sandbar willow, a native shrub that is an excellent soil stabilizer. The upper slopes, however, between the road and sidewalk, were dominated by large extents of turf. This area could be a great site for a large raingarden, which would capture and pre-treat stormwater runoff from the impervious surfaces upslope.
Boom Island
This park was dominated by large expanses of turf grass. At the time of the field survey, there were large areas of new sod. The shoreline buffer was rather thin and narrow. This park is clearly targeted as a recreational area, and no restoration is recommended here. It would be nice to widen the natural area buffer for water quality benefits, though.
Bassett Creek Confluence
Just south of the Plymouth Avenue Bridge, on the west bank, is the mouth of Bassett Creek, which enters the Mississippi through a manmade tunnel. In terms of plant diversity, the condition of this site was degraded: there were many exotic shrubs and herbaceous plants that dominated the site. Also, the corner of the mouth of the creek on the north side had extensive areas of bare, loose soil, indicating that strong erosive forces are at work here. The good news is that there were several large cottonwoods scattered along the creek mouth. This area could be improved by planting native shrubs.
B. F. Nelson Park
A new prairie and shoreline stabilization areas had been installed at B. F. Nelson Park and were in good condition. The prairie was quite diverse. Some exotic forbs (including spotted knapweed) had invaded (especially towards the retaining wall), but that is to be expected in a new restoration. We recommend controlling the knapweed immediately, before it spreads. Burning the prairie every two to five years also is recommended.
Nicollet Island (north of Hennepin Ave.)
This area offers some real great opportunities and some big challenges. The northern tip of the island and the channel areas across from B. F. Nelson Park both support a fairly extensive natural area. The bank on the far north tip was very high and affords commanding, scenic views to the west. The bad news is that it was greatly disturbed: large areas of bare soil were actively eroding, with much loose rock and debris on the slope. This slope should be stabilized. The good news is that the plant community here was in fair condition, with a decent amount of diversity, with some large cottonwoods at the toe, and figworts and zig-zag goldenrod in the ground layer. Some areas on the slope had prickly ash and stiff goldenrod, plants found in a dry woodland or savanna. For some reason, there was no garlic mustard, which was not the case for the rest of the island. Once this slope is stabilized, this area could be planted with a diversity of native dry woodland species and others. With the help of local volunteers, the planting area could be monitored regularly for garlic mustard to keep it from invading.
The upper parts of the north end of Nicollet Island also offer opportunities for restoration. Here was found a fairly large open field, now dominated by smooth brome and Canada goldenrod. A couple of large hackberry trees grace the area. This field potentially could be restored to prairie/savanna with not too much trouble. One consideration would be whether burning could be done. If not, then prairie restoration is probably not possible.
We also assessed an area near the DeLaSalle football field that had been previously restored to native prairie. It could use a little more ongoing management, such as burning, selective cutting, and weeding.