As work continues on the $60 million Crane Valley Dam Seismic Retrofit, concerns about the affects of the project on Bass Lake's Kokanee salmon population have been raised by fishing guide Todd Wittwer.
Wittwer, who has owned a Kokanee guided fishing tour business for 12 years, has been fishing at Bass Lake since 1993. After noticing that he was out-catching other fisherman, he decided to start a business, but for the first time since he started his business he has had to shut down his boats mid-summer because fishing lines are coming up empty.
Wittwer said fishing has always been steady until this year, usually running three boats at the height of the season. He starts taking people out on tours the first of April and this year Kokanee numbers were good as well as their size. Normally, he's catching Kokanee through September, but by mid-May he was noticing that there weren't as many fish. He said his boats usually follow the Kokanee from the sheriff's tower down the lake towards the dam, but he began to notice that they were chasing the fish north instead of south. On July 15, he pulled up his lines and shut down all his boats for the season.
Wittwer, who submits a weekly Bass Lake fishing report to the Fresno Bee, has concerns that the sediment caused by dredging at the retrofit project has killed the Kokanee, although sediment in the water, or turbidity, can also be caused by algae and boating activities. Wittwer said high turbidity levels can be lethal to fish because they breath through their gills. If sediment levels are high, fish aren't able to breathe or eat and suffocate or starve to death.
Fish & Game not overly concerned about Kokanee
The Department of Fish & Game says they aren't concerned at this point and PG&E says they are taking all the proper steps to ensure the safety of fish and the environment by running turbidity checks regularly.
Brian Deal, senior environmental scientist supervisor for the California Department of Fish & Game, said there is less cold water available for the fish this summer so its likely that they are more stressed than normal, which tends to shut fishing down because they aren't hungry and biting.
Deal said that at certain conditions, when temperatures are high or oxygen is low, Kokanee can't assimilate food and shut down. He said that the upper layer of water at Bass Lake is almost lethal to Kokanee this time of year due to high water temperatures but that happens every year and the Kokanee have to stay low in the lake.
Andy Gordus, Fish & Game toxicologist, said that turbidity pockets that formed where the Kokanee prefer to go may have also forced them to go down to lower, colder waters. At that point, Gordus said they are in a lower metabolic state.
However both Deal and Gordus said that Fish & Game has no evidence that the fish have died off and said the turbidity lens does not cover the entire lake. Gordus said if a lot of fish had died, a lot of dead fish would have appeared at the surface. Fish & Game has been tracking water quality very closely and PG&E sends them reports weekly that are reviewed by water quality specialists.
"They (PG&E) were real good about it and keeping us informed," Gordus said. "Our preference was for them to get done as soon as possible and get out so conditions can get back to normal."
PG&E working with many agencies
Gordus said PG&E was submitting reports monthly but when turbidity began to rise Fish & Game asked for a weekly report and received daily reports from three permanent monitoring sites. He said PG&E also did 12-14 more testing sites from the dam all the way up to the sheriff's tower, sampling all the way down to the bottom of the lake.
Denny Boyles, PG&E spokesperson, said they are taking several steps to protect water quality in the main body of the lake as well as downstream, in the North Fork of Willow Creek and they are working with a number of agencies to do so. Those agencies include Fish & Game, The Regional Water Quality Control Board, U.S. Army Corps of Engineers, the U.S. Forest Service, California Department of Water Resources and the Federal Energy Regulatory Commission.
Boyles said these steps began before the retrofit project even began with an 18-month public environmental review. the review process was overseen by the California Department of Water Resources and used independent third-party water quality experts and fisheries biologists to identify potential impacts of the project and develop specific measures to avoid or reduce potential effects. He said PG&E has also worked with Fish and Game and the Water Quality Control Board for more than 12 months designing a water quality monitoring plan and identifying water quality protection measures.
Some of those efforts include a 24 hour a day, seven days a week water quality monitoring program, two separate curtains to separate the loose sediment of the work area from the rest of the lake, scheduling in-lake construction activities to minimize environmental effects and having divers on-hand to check both curtains weekly.
Boyles said they even did both fish and turtle rescue operations prior to the start of dredging to capture and remove fish and turtles from the dredging area behind the turbidity curtain.
Before the dredging began, PG&E measured the turbidity levels from July 22, 2011 to Feb. 22, 2012. Boyles said those levels ranged from a 0.3 Nephelometric Turbidity Unit (NTU) -- how much sediment is in the water -- to a maximum of 20.30 NTU. The latest readings range from 1.72 NTU to 41.7 NTU.
"These levels are not known to be lethal to fish that occur in the lake, and are within the range of turbidity that naturally occur within the Sierra during spring runoff and winter rainfall events," Boyles said.
However Wittwer said some numbers were reported to him by Fish & Game that were much higher. He said he was told that on May 16, NTU levels were 15-70 with pockets upwards of 151. He said levels remained high but in the last two weeks have begun to drop.
According to PG&E spokesperson Nicole Liebelt, the highest average 24-hour turbidity measured in Bass Lake was 47.8 NTU July 7 at one of three in-lake monitoring points. Liebelt said these numbers are within the range of turbidity that occurs during spring runoff and winter rainfall events.
Deal said that these levels would normally not result in lethal conditions for fish.
"We're hoping that things aren't as bad as some might predict," Deal said.
The dredging along the base of the dam was completed July 30, according to Boyles. Project engineers and regulatory agencies signed off Aug. 3 that the dredging had met all specifications.
Deal said they expect the sediment levels to improve from this point on and Fish & Game will do fish assessments at the lake.
Fish plants planned
"We have been saving most of our fish allotment (rainbow trout) and will come back and re-stock the lake when temperatures cool down," Deal said. "We have a significant number, more than half a year's allotment. They'll be full grown, catchable and ready to put in a frying pan."
Deal said that allotment will be about 7,000 pounds (about 14,000 fish) and they expect to restock in September or October. The fish will be a little over a year old, half a pound each and 12-13 inches in length.
Fish & Game will also re-stock 50,000 fingerling Kokanee in April or May of 2013, Deal said, but the fingerlings are only one to two inches long and will take a year for the fish to mature.