Originally published in our September 2011 newsletter.
By Jon Dittmar, Cardno JFNew
Wolf Lake is a 3.2 km² natural lake located on the Indiana/Illinois border near Hammond, Indiana. In pre-settlement days Wolf Lake was part of a vast complex of dunes, lakes, marshes, and wooded uplands. Ecologists refer to this area as the Lake Plain as it was once the bed of Lake Michigan. Development impacts, including dredging to obtain construction fill, filling with construction spoil, industrial discharges, invasive species encroachment, and other nonpoint sources of pollution have significantly altered Wolf Lake. In the 1950s the Indiana Toll Road (I-90) was built through the middle of the lake.
Despite these anthropogenic impacts, Wolf Lake still attracts fishermen, boaters, wind surfers, birders, and other nature admirers. It also offers habitat for a wide variety of wildlife and plants, including species listed as threatened or endangered such as the lake sturgeon (Acipenser fulvescens) and banded killifish (Fundulus diaphanus).
The Wolf Lake Aquatic Ecosystem Project was initiated by the U.S. Army Corps of Engineers (USACE) Chicago District under Section 206 of the Water Resources Development Act of 1996, which gives USACE authority to undertake restoration projects in aquatic ecosystems.
The city of Hammond, Indiana was the project owner and a major project collaborator. The city provided part of the matching funds for this 6.5 million dollar project and is responsible for long-term maintenance. Major project features include restoring 1.6 km of eroded shoreline, creating 0.10 km2 of aquatic and upland native plantings by constructing more than 30 sand islands, restoring natural water levels, improving boat channels, and controlling invasive plants. In 2009 the city of Hammond received a Conservation and Native Landscaping Award from the U.S. EPA and Chicago Wilderness.
The Wolf Lake Aquatic Ecosystem Restoration Project is unusual in that wetland and upland habitats were created in shallow open water lake areas by constructing islands by hydraulic dredging of bottom sand. Material removed from the lake bottom created deep holes, which enhanced benthic diversity of the lake bottom. The extracted sand created islands with elevations suitable for emergent wetlands, wet prairie, and sand prairie depending on the elevations.
The benthos of Wolf Lake contains little organic matter or nutrients and as a result it is a less than ideal planting medium. We also anticipated that the lake’s high winds would hinder stabilization of the newly formed sand islands. Wave and ice action accompanying these winds had been destructive to previous shoreline restoration and stabilization efforts. Herbivory, particularly by muskrats, carp, and the resident Canada goose population was also expected to be a challenge for establishing plants on the islands.
The project plan used several methods to mitigate the potential effects of a less than ideal planting medium, wind erosion, and herbivory. Erosion blankets anchored with 46 cm landscape pins were installed along the shoreline of the newly created islands to protect the wet prairie seed. Emergent plant plugs were secured with 20 cm steel staples. Plant species selected for the seed and plug mix included fast-growing stabilization workhorses like Chairmaker’s rush (Scirpus pungens) and Softstem bulrush (Scipus validus), along with annual rye (Lolium multiflorum) and oats (Avena sativa) for quick cover. The plant and seed mix contained more than 100 native species in the hope that it would result in a diverse native plant community representative of pre-settlement ecosystems. A system of 46 cm tall chicken wire fencing and nylon cord was also installed to protect the 4.6 m wide emergent planting zone from predatory geese, muskrats, and carp. In critical energy zones, unvegetated sacrificial barrier islands were created to protect vegetated islands during the early plant establishment years.
Island construction began in late summer 2006 and seeding and planting commenced in spring 2007. The prime contractor was Luedtke Engineering of Frankfort, Michigan and they were responsible for performing the hydraulic dredging and island construction. Cardno JFNew provided all plant materials, installation, and initial vegetation maintenance.
Many planting and seeding areas were lost or damaged by agents of nature despite all the protective features incorporated into the design of the sand lakes. Some of the problems that occurred:
The restoration community may benefit from the lessons learned on this project. Future designs using dredged spoils to create sand islands within lakes should consider the following:
As with any restoration project, ongoing management is essential to control the advances of non-native aggressive species and maintain biotic integrity. During project design the USACE developed an operations and maintenance manual that will guide long- term management of the native areas. Wolf Lake is particularly vulnerable to the advances of phragmites (Phragmites spp.), purple loosestrife (Lythrum salicaria), and Eurasian watermilfoil (Myriophyllum spicatum).
Project ownership has transitioned from USACE to the City of Hammond. The city is now responsible for managing these species and aggressive native plants like cottonwood and willow. In certain areas, wave and wind erosion requires periodic reinforcement of protective measures such as wave barriers and erosion control blankets, and replanting of native plant plugs. Periodic prescribed burning of upland areas is also planned.
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