Informative article by Judi Bowers of the Big Bear Grizzly.
Weeds. There are good ones and bad ones. There are required weeds and ones that you want to get rid of in hopes they never come back. And if you are the Big Bear Municipal Water District, weeds are on your to-do list every day.
Also called aquatic plants, weeds were the subject of a recent MWD workshop. And apparently weeds gain the attention of more than Mike Stephenson, lake manager. The board workshop drew seven people and a reporter to the audience, the largest attendance at a MWD meeting in some time.
The MWD began harvesting weeds in the 1960s, introducing the use of the Aquamog from 1984 to 2004. No one knows when Eurasian milfoil found its way to Big Bear Lake, Stevenson said. Milfoil is not native to the lake and is highly invasive. Native aquatic plants include coontail, curly-leaf pondweed, common elodea, widgeon grass, water smartweed, sago pondweed and chara, which is macro algae.
Coontail is also considered invasive, and the curly-leaf pondweed can be invasive, but isn’t here, Stephenson said. “It rears its little head and waves at me a little bit then poof—it’s gone,” Stephenson said about the pondweed’s occasional appearance in Big Bear Lake.
Current weed management efforts
• Treat milfoil with systemic herbicide
• Harvest natives for navigation purposes only
• Treat natives with contact herbicide for navigation when appropriate
• Treat all blue-green algae blooms
Current lake conditions
• 134 acres of milfoil
• 300 acres of coontail
• 100 acres of macro algae
• Fair variety of other natives
• Very high dissolved oxygen
• No planktonic algal blooms
• Very good water clarity
Managing the aquatic plant life in Big Bear Lake is a scientific balancing act. A certain percentage of lake weeds are required to meet state agency requirements for fisheries and total daily maximum load levels for sediments. The macro algae is ugly, but it’s good for the fishery.
The littoral zone is the area in which weeds can photosynthesize and grow, Stephenson explained. Right now the littoral zone is at about 1,104 acres, he said.
In 2008, the entire surface of the lake was covered with a blue-green algae. Some forms of the blue-green algae are toxic and were recently blamed for the death of 100 elk in New Mexico. Commonly referred to as pond scum, Anabaeja flosaquae, a form of blue-green algae, produces a neurotoxin that is lethal to wildlife.
The 2008 bloom in Big Bear Lake did not cause wildlife death, but Stephenson said “it was brutal,” and posed a health issue. Blue-green algae blooms are treated as they are seen, he said.
Harvesting milfoil is a bad idea, Stephenson said. That’s how Big Bear Lake ended up with 1,090 acres of milfoil in 2000. Herbicides are a better approach, Stephenson said. But removing milfoil allows coontail to increase, but Stephenson said he would rather deal with coontail than milfoil any day.
Paul Beaty, who recently retired as the owner of an aquatic management firm in the Imperial Valley area, suggested the MWD research the use of sterile fish, which will eat milfoil. It was successful in Imperial Valley and could be another tool to battle milfoil, he said.
A narrow window for treating weeds exists: June 15 to Sept. 15. Due to the dry winter in 2012-13, the streams quit running early and the temperatures in May were similar to mid to late summer, said board member Vince Smith. That put the MWD behind in its weed battle. Milfoil can grow up to a foot per day, Stephenson said.
Bob Amezquita, of Big Bear Lake, said he is concerned because the number of people coming to Big Bear to fish is decreasing. He said the decline is due to the increase of weeds.
Stephenson said based on boat permits issued by the MWD, visitor numbers don’t show a decline. Fishing may have declined for other reasons, but that’s the subject of another workshop, he said.
It’s not just fishing that is impacted by weeds, according to Jim Dooley, of Fawnskin. Dooley owns North Shore Trading Company and is the organizer of the annual PaddleFest. While not a fisherman, Dooley said it is hard to get to the beach by kayak, and he sees the problems fishermen are having due to the weeds.
The Nov. 22 workshop was a first look at the possible ways to treat weeds in the future. A full-scale harvesting program would include purchasing a second harvester, semi-tractor, conveyor and other associated equipment, to the tune of $625,000. Annually, that would cost the district about $263,000. In addition to pesticide treatments of about $106,000, the annual proposed costs sit at $370,270.
Stephenson will begin researching availability of equipment. The board asked for recommendations as soon as possible for consideration so equipment and staffing will be in place by June 15.