Council Legislation

Proposed Resolution No. R2023-164

Title: A Resolution of the Pierce County Council Accepting and Approving the 2024 Spanaway Lake Management District Annual Workplan.

Status: Completed

Sponsors: Councilmembers Amy Cruver, Jani Hitchen

Final votes

December 5, 2023
Aye Aye Aye Aye Aye Aye Aye


Documents
Additional legislative records are available below Collapse All  Expand All
 

Public Comments

Name Date Comment
Melvin Oleson 11/27/23 5:51 PM Abstract: Cyanobacteria Plan for Spanaway Lake. Concerns that proposal does not meet the facts on the ground. The recently released cyanobacteria plan (CBP) for Spanaway Lake is essentially a chemical treatment plan. This plan aims to use nutrient sequestering chemicals to deprive the toxic algae of essential components for a bloom. The plan is an effort to use known deep lake techniques to address a shallow lake challenge. Creating a pleasing aesthetic for Spanaway Lake Park visitors using temporary measures is a misuse of both county and LMD resources. Further, the treatment has potential to be ineffective in the southern portion and inlets around the lake. This plan does nothing to address the root causes of the nutrient availability that are the basis of toxic algae blooms throughout the lake. It is particularly frustrating that the facts on the ground are mostly ignored 1) In the eight years the toxic algae watch team has collected data, only once has a toxic algae bloom been noted on the main portion of the lake away from a shore line. The “fact on the ground” is that toxic algae blooms occur in a. the shallows of the southern end, b. the shallow coves on the west side of the lake and c. at the discharge channel (near the Park) to Spanaway creek. 2) The current plan to treat the entire lake with chemicals over treats and can result in ecosystem damage as “stripping” nutrients disrupts the growth of microorganisms that are the basis for the lakes food chain. 3) The source of nutrients for the toxic algae blooms is generally acknowledged to be from both south end ground water vents and “anoxic* deep water in north end of lake. This northern source cannot affect the majority of blooms, except at the Park. 4) The CBP ignores another condition on the lake- currents. The default current in Spanaway Lake is from south to north. Failure to understand the current patterns provides incomplete data for the design of the proposed spraying. It is possible that surface currents will “drift” spayed chemicals away from intended deep “anoxic” target and create adverse concentrations elsewhere. 5) CONCLUSION: treating the lake with nutrient stripping materials will be a temporary solution to the appearance of the lake, however, it is doubtful it will have any lasting effect on the actual excess nutrient problem. Only direct-action addressing nutrient inflows in the south end of the lake has the potential to address the recuring toxic algae blooms. Supplemental information: 6) Further, the actual sources of nutrients are not addressed by the CBP. While the ecosystem is bit complicated, in a nutshell: a. The ground water flowing into the lake (vents located in south end) provides substantial nutrients for both vascular plants and green/toxic algae. Current thinking is that nutrient pollution is a combination of septic systems discharge and stormwater infiltration. b. The vascular plants are fixed in place by root systems, generally in water under 12 feet depth to allow light penetration. These areas are highly oxygenated. c. Over time the vegetative material dies and is decomposed by bacteria/fungi into bottom soil (aka: muck). This soil is rich in nutrients including soluble phosphorous- a key factor in toxic algae blooms. During the spring through fall season various factors such as water temperature, wind, boat motors and currents cause plant fragments (vegetation) That vegetation settles to bottom and is decomposed. Thuse creating additional nutrient rich habitat for toxic algae. d. Some toxic algae, such as Microcystis, are known to absorb far more nutrients from muck than needed for survival. Excess nutrients that allow toxic algae to rapidly multiply (bloom) when temperature conditions are favorable. e. CONCLUSION: treating the lake with nutrient stripping materials will be a temporary solution to the appearance of the lake, however, it is doubtful it will have any lasting or long-term effect on the actual excess nutrient problem. Only direct action in the south end of the lake has the potential to address the recuring algae bloom problem. 7) Solution options: maybe there are options that can address the source nutrient problem while using chemical stripping agents as a temporary solution to the park's visitor issue. a. In the original Brown and Caldwell report there was a recommendation to install an alum injector in or near Coffee Creek. The use of Alum is generally unacceptable due to potential disastrous side effects. However, the injection of zero valent iron, a natural phosphorous inactivator, is worth investigating. Additional injectors strategically placed along the south shore and may prove beneficial. The advantage of this approach is that it will use a naturally occurring material to minimize the amount of phosphorous coming into the lake from groundwater or released by plant/bacteria action. b. The SE cove is heavily affected by the amount of vegetation blown in from the lake. (full disclosure, I live in the SE cove). During the spring there are also large algae mats that are brought to surface by gases from bacterial action. The continual accumulation of this vegetation will only lead to more nutrients being available and greater depth of “muck” in which the toxic algae can over winter. As the prevailing current in the goes to the main lake it is reasonable that the nutrients released from the vegetation are a major lake nutrient source. Thus, efforts to collect and remove this vegetation should be examined. Such actions are a must when the invasive plant spraying program has killed the plants. c. The ongoing discussion about the use of zero valent iron in areas where anoxia does not occur may well apply to the South Lake shore and west lake coves. A method to inject ZVI directly into the “muck” holds promise of depriving over wintering toxic algae of an abundant nutrient source. A mobile floating device with a water jet injector directed into the muck could be a potential solution. d. Ongoing discussion of various oxygenation systems provides another option to address the nutrient loads. A simpler and cost effective option worth investigating is to pump highly oxygenated water from the southern end of lake into the dep water “anoxic” zone in the north end. e. Other far more drastic, and expensive, approaches to ground water management and muck management exist. including the dreaded dredging option. A nutrient capture mat at ground water vents, drilling injection wells in ground water path to deliver binding agents are some examples. Hopefully, it will not come to such extreme measures if we act now to address the real sources of nutrients- not just cover them up.