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Improving fish habitat on Lake Havasu

Dec 11, 2019

As part of the Lake Havasu Fisheries Improvement Program (LHFIP), the BLM Arizona Lake Havasu Field Office is participating in a year-long study of fish habitat enhancements along the Lower Colorado River. Since 1992, LHFIP has successfully partnered with BLM to create 875 acres of artificial fish habitat and five barrier-free public fishing piers around Lake Havasu.

This project works to sustain and enhance fish populations by working with partners to actively manage habitat. The enhanced fish populations will also benefit local recreational sports fishing.

Recently, the LHFIP has identified the need to remove degraded or collapsed artificial fish habitat structures and replace them with new ones in Lake Havasu. The study requires the installation of two specially designed fish habitats, known as "reef balls" and "Georgia cubes."

Georgia cubes are three-foot square cubes made of PVC pipes and other materials. These cubes are sunk in the lake where they sit on the lake bottom and offer refuge and protection from predators for growing fish. Georgia cubes attract multiple species of fish, are estimated to last over ten years, and are ideal to replace older artificial habitat that is no longer serving as efficient habitat. Superior to previous structures, Georgia cubes have increased durability, longevity, and are more cost effective.

metal cubes holding black PVC pipe sit near a lakeshore — Georgia cubes built from PVC and drainpipe are filled with sand to ensure sinking and staying in place on the lake bottom.

Reef balls are dome-shaped concrete structures standing three feet tall with a four-foot diameter. The materials used are consistent with the best management practices for aquatic environments and will not negatively affect water quality. The benefits of reef balls also include durability, longevity, and cost effectiveness. The reef balls are distributed by boat and submerged 10 to 18 feet below the lake's surface.

honeycomb-shaped concrete structures sit on a dirt surface — Reef balls sit where they were cured in molds, ready to be submerged in the lake.

Approximately 10 reef balls and 10 Georgia cubes will be put into Lake Havasu and monitored to evaluate their potential for future use throughout Lake Havasu's fish habitat areas. While Georgia cubes and reef balls have not been previously used in Lake Havasu, they have been used successfully by state and federal natural resource agencies across the country.

honeycomb-shaped concrete structures sit on a boat — Reef balls loaded on the boat and ready to glide down the rollers into the water!

The proposed study will also include evaluations of invasive species' (like Quagga Mussel, Dreissena bugensis) potential to colonize on the habitat structures. Invasive species evaluations are critical since significant infestations on the structures could reduce the effectiveness of specific design features that are beneficial to attracting warm water sport fishes.

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BLM Arizona

Blog Topic:

Fish and Wildlife

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