The condition of Duck Lake, its inter-connecting canals, along with the rest of the 23 miles of Ocean Shores Fresh Waterways, was dissected and projected on Saturday for the second “Wine and Weeds” event sponsored by the Ocean Shores Fresh Waterways Corp.
While the wine was on the house, the weeds were the primary focus of the evening as biologist Doug Dorling of Northwest Aquatic Ec0-Systems reported on the city’s recent efforts to spray to control weeds in a number of the waterways over the past two years.
Dorling treated portions of Duck Lake, the Grand Canal and a number of other canals during 2016 under contract with the city, primarily with three different herbicides.
“This year the city took a proactive approach to the management of the problems in Ocean Shores, instead of a reactive approach,” Dorling said. Areas were surveyed and treated earlier than in 2015, and weed growth as result was not as dense in 2016.
Weed control history
Dorling noted the major aquatic weed control effort in Ocean Shores began in 2007-08, with what he described as “pretty intensive” Fluridone applications. The herbicide is one of the most successful against infestation of the weed Brazilian elodea, a state-listed noxious weed.
The 2007-08 program cost about $500,000, Dorling said. “Prior to that application, the use of the waterways, specifically Duck Lake, was almost impossible because of how severe the weed growth was,” he said.
After that, an organized effort was made to plant weed-eating grass carp in the lake and canals. In 2011, there was further herbicide treatment in the canals. No treatments were made in between 2011 and 2014, but there were aquatic weed surveys done, Dorling said.
The last two treatments were done in 2015 and again this past summer.
Technology from 2007-2016 has changed in several key ways, Dorling explained. Surveys of the lake and waterways are now more accurate using sonar technology that takes a picture of the bottom of the lake or canal. The data is used to produce three types of maps: one for weeds, another that shows the depth of the lake, and another for sediment composition.
Two areas surveyed this year include the Grand Canal and the Bell Canal. In two areas this past June, weeds were found growing up to the surface, covering 50 percent of the area with weed growth.
“We surveyed a number of canals, but these really were the two worst area that we identified,” Dorling said.
Treatment program
“It’s really important when treating in Ocean Shores, that we we want to try to apply the least amount of material to get the greatest degree of control,” Dorling said of the overriding plan in handling the ongoing weed problems.
With the budget of about $35,000 this year, Dorling and the city decided to treat the Grand Canal, the Bass Canal, all the finger canals, the small canal that enters Lake Minard, and the canal that connects Duck Lake into the Grand Canal. Even after treatment, Dorling noted, residents still called and said they continued to notice more weed growth.
That caused an additional survey with members of the Fresh Waterways Corp.
“It was a general consensus … that we really didn’t see much weed growth in the water,” he said. “But there were some other problems that were starting to occur.”
The biggest was the increase infestation of the weed pennywort, which grows along the shoreline and encroaches into the main body of water.
“Some people couldn’t even get out in the water it was so bad,” he said.
The other issue was duckweed, another fast-spreading aquatic weed. The findings caused Dorling’s company to come back and treat for the other two weeds. He estimated that 90 acres in the Ocean Shores system was treated altogether, with about 120 acres of control because of the drift of the water.
The products used in the treatments are: Diquat Dibromide for submersed weeds, Imazapyr and Triclopyr for floating weeds such as pennywort and parrotfeather.
Continuing problems
Pennywort is very aggressive, Dorling noted, and was not seen in Ocean Shores for a number of years. It’s listed as a Class A noxious weed, which means it is a weed that should be controlled.
“Unfortunately, it’s very difficult to control,” he said. “Right now, we’re just trying to maintain it — we don’t want it to spread. It’s pretty intense in some of the areas.”
The other ongoing issue is algae control. Dorling said the Ocean Shores fresh waterways have always had algae problems.
“And there is really not much you can do for how severe the algae problems are in Ocean Shores, unless you had an incredibly huge budget,” he said.
The two main algae species do have the ability to produce toxins when the levels reach a certain amount, but that has not happened too frequently in recent years (five times since 2009), he pointed out. Summer nutrient releases when the lake system is more stagnant can lead to the buildup of algae “and you get into a really nasty cycle,” Dorling said.
Contributing to the problem is all the wildlife excrement and residential fertilizers.
Treatment of algae can be done, but the primary product can be detrimental to fish if used in shallow waters, Dorling said. The other product can cost thousands of dollars to apply the right amount to control the algae.
“It’s a real touchy situation, and there aren’t very many lakes in the state of Washington that treat total algae blooms,” he said.
Some of things residents can do, Dorling advised, is to create environmentally-friendly landscaping or natural buffer areas to control the runoff of wildlife excrement and fertilizers into the fresh waterways. He also suggested residents use slow-release fertilizers that are low in nitrogen and phosphorous.
Grass Carp
A number of the 35 residents and Fresh Waterways Corp. members in attendance signed a petition against fishing or hunting for the grass carp that were planted to control weeds in the past. Dorling said the state Department of Fish and Wildlife has changed its former approval of using the weed-eating fish to control weeds.
“The grass carp are very efficient,” Dorling said. “And if you have enough of them, they will control the weeds. The problem with the grass carp … remember every thing the eat comes out the other end. So in lakes, where we plant grass carp, it looks great for three or four years, but then the nutrient level starts to build up.”
Now, Fish and Wildlife does not want grass carp planted anywhere, Dorling noted. “They want to eliminate the grass carp,” he said. As a result, the state last year proposed allowing the fishing and bow-hunting of grass carp on Duck Lake, despite local objections.
Those who signed the petition plan to present it to the City Council to ask for a city ordinance preserving the carp.
