October 25, 2007
Pahranagat Lake Update

By Dave Maxwell

Photo by Dave Maxwell
Dry north marsh at Pahranagat Lake.

An inspection of the dam at Upper Pahranagat Lake October 15 showed the problem with the dam structure could not be fixed this year as had been hoped. Wildlife Refuge manager Merry Maxwell said they have learned that they will have to draw the lake down early next year.

The north marsh and Upper Pahranagat Lake have been in the process of being drained for the past couple of months to try to find out why water was continuing to flow out of the lake even when the shut-off gate was closed.

“What we’ve learned," Merry said, “is that we have some scaling of iron on the wheel itself that opens the water control structure and gate (which are right underneath the fishing pier).” Those can be dealt with now. “However,” she went on, “the biggest problem is that when the dam was built, a trash rack that was installed to keep boulders and debris out of the culvert unfortunately was not extended to the sides of the structure. Boulders and debris are falling into that culvert, blocking it, and creating these damning events that build up and then maybe break free (causing some wash-outs further down on the refuge). Also boulders have fallen into the culvert and we can’t close the water-tight gate to keep the water in the lake.”

After engineering took a look, she said, it was determined there is still too much water going through the culvert, so they cannot get in to remove the boulders. The decision was made to draw the lake down again next year, probably as early as August. In addition, some new trash racks will be built to put on the sides of the water structure to solve the problem.

The lake did not drain nearly as fast as has been hoped, Merry said. “It was more difficult to drain than I anticipated. We really underestimated the volume of water in the lake,” she said, “and the lake appears to be filling in with sediment.”

"We didn’t pull it all the way down this year, and I don’t think we had much of a fish die-off, either, if any,” Merry said. There is only about a foot of water in the lake right now and, “It is amusing to watch the ducks and geese walking around in about 12 inches of water,” she said.

The carp fish are still there, too, she said. “They’re pretty tough. They can hide in the mud for a long time.”

At present, farmers to the north of the refuge, who have been diverting the water from the lake, began allowing water to flow in again in October, so Upper Pahranagat Lake and north marsh will soon begin to refill.