EelStream Eel Passage System 2022 Field Evaluation.

Truebe, Eric, Jonathan Truebe, Lakeside Engineering, Inc., Mirror Lake, NH

The EelStream (Patent Pending) is a novel means of providing upstream eel passage that addresses some of the limitations of traditional eel passage structures. The EelStream is comprised of a chamber that collects eels from a short climbing structure. Pinch valves on the chamber inlet and outlet are periodically cycled while the chamber is filled with compressed air. This flushes eels and water from the chamber through a 1.5-inch transport hose over the dam. A small flow of water is continually siphoned though this hose from the headpond and screened to provide transport flow to the climbing structure. This provides a guiding current for eels to swim volitionally through the hose between flushing cycles. The EelStream was evaluated at the Cocheco Falls Dam in Dover, NH during the spring and summer of 2022. The goal was to determine survival rates and transfer time through the system. Three test scenarios were performed with varying exit pipe lengths from 100 ft. to 200 ft., and lift heads from 17 ft. to 33 ft. Eel sizes ranged from 50mm to 350mm. The overall 96-hour survival rate for all tests was 99.3%. For all tests over 95% of eels passed from the holding chamber through the transport hose in less than 5 cycles with a 10-minute cycle time. Over 10% of eels exited the hose volitionally between flushing cycles. With low eel mortality and relatively rapid passage time, this technology shows promise, particularly where traditional eel ramps are challenging to install and maintain.