Introductory Notes: Many people have asked the question why wasn’t the electric fish barrier turned on? The reason is there is only a few inches of water on the deck right now and with the electricity turned on the fish are immobilized and can’t get off the wide deck and they die there. Then we have the dead fish smell and the accusation the mean DNR is killing the fish. The electric fish barrier is a new design that doesn’t need the electricity turned on to keep the Asian carp from swimming upstream. With the rocks below the dam the downstream fish can’t make the jump. With additional rain, the barrier is now turned on and is at work protecting the lakes.

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The new fish barrier shows a caution flashing light when activated. Although the electricity level used is not fatal to humans or fish, it’s recommended that people do not go around the fence.

Courtesy KUOO – Explore Okoboji – Wednesday, 5-29-2013

(Orleans)—While most of the work has been completed and the structure has been functional since mid-February, the electronic fish barrier that’s been installed at the Lower Outlet has not yet been turned on, other than for testing purposes. The barrier was installed last fall and winter as a method of hopefully preventing any additional asian carp from getting into the Iowa Great Lakes.

The fact the fish barrier isn’t yet in operation is making some in the lakes area nervous now that extensive flooding is taking place downstream on the Little Sioux River. Mike Hawkins, a fisheries biologist with the Iowa Department of Natural Resources, says his office is responsible for operation of the barrier. He tells KUOO news they’re closely monitoring the situation and that if they feel conditions warrant, they may energize the barrier as early as this (Wed.) evening.

“Well we’re definitely under the gun and this is the situation that the fish barrier is designed for,” said Hawkins. “We’ve got flooding downstream that could potentially allow asian carp again to move upstream and so what we’re seeing right now is the lakes have come up from an 18 inch low. They were 18 inches below crest this last winter. They’re now about two inches or so above crest. So there is water going over the deck of the fish barrier. We’ve been monitoring it very closely, almost hourly, just to kind of watch and see what’s happening with the fish. We have a few fish on the upstream side that are attracted to that current and once in a while are kind of getting swept over the barrier. There are fish downstream but at this point they’re not able to make it over. The barrier is designed to prevent fish from migrating even without electricity up to a certain point and at a point that will maybe occur in the next couple of days if we get some rainfall we’ll be turning it on. So we’re right at the tipping point where we’re going to begin to need it to stop that upstream migration of fish.”

Hawkins says that as of right now, a bench mark as to when the system should actually be turned on hasn’t been set yet.

“That point is yet to be determined,” he said. “We’re learning as we go here on what fish are able to do because it is a new structure and there’s things to learn on it. We’re kind of finding out what that point is. I’m guessing another inch or inch and-a-half in water level rise and we’ll be turning the system on, and then it would stay on until the water would recede back down. We have done some tests on it. In fact I did a test, a remote start up, just a day or so ago and we were very effective at moving fish away from the barrier on the top, on the upstream side. Everything looks to be ready to go and it looks like it’s going to be quite effective.”

Meanwhile, Hawkins says additional carp have been spotted in the area.

“We have seen asian carp below the Iowa Great Lakes dam,” said Hawkins. “This spring we had some bow-shot asian carp that were there. I think they may have been trapped. there over last winter. It just really adds to the validity that those fish are present and it looks like we’re going to be living with them in the long term, and these flood events just continue to bring fish upstream or allow them to come upstream, so…”

On a positive note, Hawkins says he does feel much more comfortable than he did a year ago knowing the fish barrier is ready to go.


Additional Information from Mike Hawkins – Thursday, May 30

The fish barrier was activated this morning a little before 10 am. Last night’s rains weren’t nearly enough to raise water levels enough to allow fish to pass upstream, but we’ve always planned on being conservative with the start up. Even though you can’t see it from the road or parking lot, there is still about a two foot drop on the downstream side of the barrier.

When the system started up all of the fish (mostly common carp) that were near the barrier quickly moved away and have stayed away. I spent much of the day observing fish behavior around the barrier and am very pleased with the reaction of the fish so far. I have not seen a fish get closer than about 10 feet from the deck before quickly turning away. In fact, if you visit the site you won’t see much of anything, which is a good sign.

We’ll keep the barrier operational until water levels fall lower than their current level.

Facts about the barrier:

  • There are seven pulsators that generate DC current to the 8 steel electrodes that span the deck. Pulsator 1 is hooked to the first and second electrode (positive/negative). Pulsator 2 is hooked the second and third electrode (negative/positive) and so on.
  • The pulsators operate simultaneously and come on for 2 milliseconds per pulse and pulse 5 times per second. These settings are adjustable and can be customized for the conditions and the type and size of fish.
  • Each pulsator is drawing about 300 watts of electricity(about three lightbulbs).
  • The control building has a generator that will restore power 12 seconds after a power failure. Unlike any other fish barrier in the country, ours has a battery backup for pulsator 1. This allows the first pulsator to operate at full power even during the 12 seconds it takes for the generator to restore full power. This should keep fish at bay for that short period.
  • The system has a water level sensor that uses sound to determine the depth of water on the deck. This sensor can be set to automatically activate or shutdown the barrier at preset depths.
  • The entire system can be monitored and controlled remotely from a computer or smartphone.
  • The barrier system sends an email each morning at 6:30 to a number of local personnel to provide a status and log of everything that has happened in the past 24 hours. The system will also page key personnel if there is an warning condition such as a malfunction, security breach, power outage, etc.
  • Smith-Root Inc., the barrier manufacturer and designer, monitors the barrier continuously and can make minor changes and software upgrades from their office in Washington state.
  • Only about 50 electric fish barriers are operational in the US. More are on the way as the spread of Asian carp continues. Most of the 50 or so in operation today were installed for trout and salmon or for preventing common carp from entering wetland spawning areas.