PROJECT

CROOKED LAKE

Diver Assisted Suction Harvesting
(D.A.S.H.)

Location

Crooked Lake,

Lindenhurst, IL

Introduction

Crooked Lake is a glacial lake in unincorporated Lake County and Lindenhurst. Like many lakes in urbanized areas, excess nutrients feed exotic and invasive plant species like Curlyleaf Pondweed and Eurasian Watermilfoil that tend to crowd out native species when left unmanaged. An overabundance of these plants can interfere with recreation, including boating and swimming.

Services

Diver Assisted Suction Harvesting (D.A.S.H.)

ILM Diver Assisted Suction Harvesting (D.A.S.H.)

Details

A new waterfront homeowner was surprised to arrive at her new home in early summer to find the waterfront overgrown with invasive Eurasian Watermilfoil. She had planned a party for her son to kick off the summer but was disappointed to find conditions unsuitable for swimming. She needed a quick fix to the problem and contacted ILM to remove the plants mechanically.

Since Eurasian Watermilfoil is a deeply rooted plant and, therefore, difficult to remove, the best solution was to pull the plants out by hand (not unlike weeding a garden on land) through a process called Diver Assisted Suction Harvesting (DASH). The diver (using a snorkel or breathing apparatus to stay underwater) weeds the plants from the lake bottom and feeds them into a suction hose. The hose carries the plants to the boat and deposits them on a sorting table where staff pull out any creatures sucked up as bycatch and return them to the water. The plant material is placed into biodegradable bags, hauled off, and composted.

Eurasian Watermilfoil spreads by fragmentation, so it is important to keep fragments from floating away and growing into new plants. Topside staff watch for fragments and net them out of the water.

It took two days to clear around the dock for swimming, but at the end of day two, conditions were perfect for a party.