Recent Q&A of District

There are many factors that influence aquatic growth in Moses Lake, including temperature and nutrient loading. One way various algae growth is reduced in Moses Lake is by the delivery of low nutrient water from the Columbia River by USBR (dilution flows). Due to the wind, the benefit of the low nutrient incoming Columbia River water is apparent and detected at least half way up into the north arm of the lake and reflected in water test results. USBR dilution flows from 2002-2016 averaged 260,000 acre-feet annually through Moses Lake. In 2017 and 2018, 76,000 and 75,500 acre-feet respectively of dilution water came through Moses Lake. This undoubtedly has contributed to the algae blooms this year and MLIRD is working with others to see if dilution flows can be increased in the future.

Q: The MLIRD has a water quality testing unit. Is the MLIRD still using it to test the lake?

A: Yes, and last year MLIRD also added lab water sampling to test for nutrients. This is in addition to the Sondé testing you refer to.

Q: If so, are the results being posted for the public?

A: Yes, they are on the MLIRD website: This Page. The website also has reports comparing lake water quality from the start of the dilution project in 1977 to present.

Q: If the lake is being treated each year what company is doing the treatment?

A: Since 2016, Aquatechnex has had the contract.

Q: What is the name of the product they are using?

A: Aquathol and Diquat. There has also been some spot treatment for green algae. Pak27 was used for that but on a lake as large as Moses Lake, spot treatments are not very effective.

Q: Where are the treatment sites?

A: Available here

Q: How much does it cost to treat the lake each year?

A: MLIRD budgeted $190,000 for conventional aquatic treatments for the last two years - more than allocated in recent years. MLIRD estimates that treatment of the north end of the lake which in 2018 was a problematic source/area for blue-green algae to be around $250,000 per treatment. In years like 2018, there would likely need to be 2 or 3 treatments so the estimated annual cost could be $500,000 to $750,000. Further, there would be no guarantees as to how long it would last. Accordingly, MLIRD believes the best long term solution is to increase dilution flows and decrease nutrient inputs into the lake.

Q: If the lake isn’t being treated is dilution the only process being used to try and keep the algae to a minimum?

A: Yes. Dilution water has generally been an effective control on phosphorus concentration which fuels algae growth.

Q: Is there any empirical evidence that dilution is effective?

A: Yes. The MLIRD monitoring results before, during, and after adding dilution water is convincing. Extensive data over the past 40 years of the dilution project shows that dilution is highly effective (see annual MLIRD reports on the website).

Q: If Moses Lake is toxic, and the water is moved down into the Potholes, doesn’t that impact the water quality of the Potholes?

A:Moses Lake water itself is not toxic. Wind-blown accumulations of blue-green algal species near shore have shown high levels of a toxin. Concentrations of that species were many times less abundant in the open lake water and they were not abundant near the outlets to the Potholes. Dilution of Moses Lake with low-phosphorus Columbia River water results in lowered phosphorus concentrations entering Potholes.

Q: There are three hatcheries upstream of Moses Lake via Crab Creek and Rocky Ford Creek. Is this a problematic source of phosphorous contamination?

A: Possibly. The Rocky Ford Creek source was shown to contribute high phosphorus to the creek by Dept. of Ecology scientists in 2001.

Q: Is anything being done about the aging, and inappropriately placed, septic systems around the lake?

A: Not to MLIRD’s knowledge. This is a significant problem beyond MLIRD’s control. Ground water testing near the lake by Dept of Ecology scientists in 2001 showed higher than background phosphorus concentrations at several sites. Some of those data are summarized in the 2017 MLIRD report.

Q: Is there a Lake Management Plan?

A: There is an MLIRD Integrated Aquatic Vegetation Management Plan. MLIRD intends to develop a Lake Management Plan to treat uncontrolled sources of nutrients.

Q: If there is, is it being followed and updated every two years?

A: See above.

Q: If it is currently in use is it available for the public to view?

A: The current plan is available. Any new plan will be available to the public when completed.

Q: We understand that a TMDL is a plan of what reductions in a pollutant are needed to restore a water body to meeting State Water Quality standards. So, the requirement for a TMDL is only triggered when the State has officially determined, under the Clean Water Act, that a pollutant exceeds the State's water quality standard for a particular pollutant(s). What happened to the 2003 TMDL, Publication #0-3-0-3-0-0-5?

A: It is available at the Washington Department of Ecology website: HERE

Q: What is the difference between a TMDL and a 303d and can the two be implemented together?

A: Total Maximum Daily Load (TMDL) is a regulatory term identifying the maximum amount of a pollutant a lake can receive and still meet quality standards. The term 303(d) refers to a list of impaired waters.

Q: Would charging a launch fee at the County Parks be of any benefit?

A: Every bit of funding helps, but a launch fee would likely not generate enough revenue to fund significantly larger lake treatments for various algae. To help with that, MLIRD is always looking for new ratepayers. Please join MLIRD and start contributing to its efforts to improve lake quality. Forms are available at MLIRD to petition your property into the MLIRD boundaries to do so.

MLIRD is hopeful that by answering these questions, and by working together, we can all begin solving the problems as quickly as possible.

For more on Moses Lake water quality history click HERE

October/November 2018