December, 2017

Friends of Spanaway Lake (FOSL)

Toxic algae control Capital funding Request

Our Mission

  Friends of Spanaway Lake (FOSL) is a group of homeowners, sportsman, boaters, fishermen, and other citizens who are concerned about the health of Spanaway Lake. The citizens are forming a 501-C3 organization. Its goal is to protect and enhance water quality, fishery and wildlife habitat of Spanaway Lake for recreational users and homeowners. We are committed to preserving the health of our lake for present and future generations.

Lake Features

  Spanaway Lake is a large, natural kettle lake in central Pierce County, Washington. An area of approximately 17 square miles drains into Spanaway Lake, which has a surface area of 272 acres. The average and maximum lake depth are approximately 16 and 28 feet, respectively. The largest source of water to the lake is groundwater 60%, which contributes approximately 65 percent of the inflow to the lake. The main surface water source to the lake is a wetland system on Joint Base Lewis McChord that feeds into Coffee Creek on the south end of the lake. Water discharges from the lake at the north end into Spanaway Creek and is believed to have underground connections to other waterbodies.

 The lake supports a variety of beneficial uses including boating, fishing, swimming, and wildlife habitat. More than 170 single-family homes and 160 multi-family residences have direct access to the lakeshore. Pierce County operates its second  largest regional park on the northeast shore of the lake allowing public access. Spanaway Lake Park has swimming beaches, a boat house/pier/ ramp, shore fishing access and other amenities that attract approximately 500,000 visitors per year.

Water Quality Issues

Spanaway Lake has a history of cyanobacteria (i.e., blue-green algae) blooms that have the potential to release toxic substances harmful to people, pets, and wildlife. Tacoma Pierce County Health department (TPCHD) algae advisories have been common for Spanaway Lake during the past 10 years.                       

Spanaway Lake samples had some of the highest concentrations of the algal toxin microcystin of the 30 Washington State lakes sampled during 2007–08 from the Washington State Department of Ecology (Ecology) Freshwater Algae Control Program. Thirty-eight of 60 water samples collected from Spanaway Lake from September 12, 2007, to June 1, 2016, exceeded 6 μg/L, the state recreation guideline value for microcystin (Washington State Toxic Algae website, https://www.nwtoxicalgae.org/ July 2016).

Cyanobacteria blooms in surface waters are typically associated with elevated nutrient loadings. Phosphorus is typically the nutrient that accelerates cyanobacteria growth in western Washington lakes. Ecology’s 2015 Water Quality Assessment 305(b) Report and 303(d) list identifies Spanaway Lake as a “water of concern” for total phosphorus (TP) (Ecology 2015).

  The primary nutrient of concern in Spanaway Lake is total phosphorus (TP), which fuels both algal blooms and the growth of rooted aquatic plants. Excessive growth of algae and rooted plants settle to the lake bottom, where they decompose and reduce DO and adversely affect pH in the lake water. Low DO and high pH levels are harmful to fish and other aquatic life.

There are nearly 4,000 onsite sewage disposal systems (OSDS) located upgradient of Spanaway Lake. Surface failures are rare because of the very permeable soils, but phosphorous from OSDS can move through the soil to reach the lake through groundwater flow. Septic systems installed in shallow groundwater areas close to the lake have the potential to contribute fecal coliform bacteria to the lake via groundwater transport. Model estimates indicate that OSDS currently contribute on the order of 53 kg to 89 kg of phosphorus to the lake each year, which is about 17 to 20 percent of the current groundwater load to the lake. Because groundwater and the associated TP tend to move very slowly in the subsurface, the model predicts that the number of OSDS that affect the lake and OSDS TP loads will slowly increase over time.

   Fecal bacteria are also a concern for Spanaway Lake. Ecology’s 2015 Water Quality Assessment report lists Spanaway Lake as “impaired” based on elevated fecal coliform bacteria concentrations in samples collected during 2003–10 (Ecology 2015).

  An excessive amount of phosphorus has also fueled the explosive growth of native and non-native aquatic plant growth that is choking parts of the lake. Two non-native, invasive species that we know of in the lake are (fragrant water lily and curly-leaf pondweed). Non-native plants can often spread aggressively and outcompete native species, harming lake recreation and ecology.

Solutions Challenges

The Brown and Caldwell study conducted between 2015 and 2016 has generated a list of possible solutions to the toxic algae and related water quality challenges. (attachment 1) While several of these options provide a short-term solution; each of those options fails to address the source problem- phosphorous in the lake sediment and inflow from ground water.  Some of the options listed will create problems with downstream waterbodies by mobilizing the phosphorous so that it can flow down Spanaway Creek into these waterbodies.  It is probable that the phosphorous levels will exceed water quality limits (environmental) in the creek and downstream water bodies. 

The options listed to “stabilize” the sediment through use of alum and similar techniques is recognized to have a fatal flaw in a shallow lake, such as Spanaway Lake’s average depth of 16 feet.  Sampling taken during 2017 has demonstrated that the heavy power boat traffic’s prop wash and prevailing winds have created a uniform mixing to a level of 18 feet in most parts of the lake.  This mixing will de-stabilize the bottom and resuspend the phosphorous to feed the algae blooms.  Further, stabilization materials are known to adversely affect macro and micro flora and fauna in waterbodies.  This will upset the food chain and create a host of unintended consequences with fishery and wildlife.

Septic systems are a known source of Phosphorus to the lake via ground water discharge.  The impact of these systems is expected to continue into the lake for at least the next 200 years from existing systems based on ground water flow rates and expanse of the lake’s drainage.  The Brown and Caldwell study indicates that we have less than 25 years to stop or mitigate the inflow to prevent Spanaway Lake from going into an Eutrophic state- a dying lake.  Even if septic systems were immediately removed and discharges transferred to a publicly owned treatment work it would not be soon enough to prevent the lake’s demise as an high value asset to the public and home to wildlife.  We also recognize the economic, technical and political difficulty in making such a broad change in how wastewater is treated in the Spanaway lake drainage.

Evaluation:

Recognizing the challenges to success for most of the listed options it becomes apparent that some mechanism is needed that will either 1) prevent further input of phosphorous into Spanaway lake at levels that exceed the natural discharge rate.  2) Create an exemption to water quality standards to allow excessive phosphorous discharge into Spanaway creek so that options that resuspend phosphorous can be implemented. 3)  Periodic removal of sufficient lake sediment or plant/ algae material to counterbalance the current and projected inflow of phosphorous.

Each of these options will require a significantly better understanding of the lakes dynamics and ecosystems to obtain the necessary permits and funding to implement.  Specifically:

1)      Preventing further input will require either diversion of the water to another discharge or removal-treatment and return system (also known as pump and treat).  This approach is commonly used in managing toxic plums at hazardous waste sites, leaking underground storage tanks (i.e. gas stations) and some agricultural areas where water needs to have elements removed prior to irrigation use (i.e. selenium).  The design and implementation of a pump & treat system requires extensive knowledge of the ground water flow patterns and chemical composition.  If successfully implemented such a system would consist of multiple wells and treatment complexes that can operate for decades.  It would have very little direct affect on the lake since minimal work in the lake proper would be required. 

2)      An exemption to water quality standards can be achieved by requesting a variance or, in some cases, requesting a Total Maximum Daily Load (303d) be established.  In either case the local government, in cooperation with the State would become responsible for implementing measures to control the input and discharge of phosphorous from Spanaway Lake.  A comprehensive plan would be created that would become a binding agreement on efforts to be taken by various parties to reduce phosphorous inflow to levels consistent with outflow.  Under these terms it would be possible to increase the outflow of phosphorus to surface water using techniques such as turbulators or oxygen injectors.  Another alternative is to discharge high phosphorus water to ground water wells down flow from the lake basin.   In any case it will take knowledge of the impact of the proposed options to obtain permits and agreements, let alone funds, for this approach.  This approach will have some direct impacts on Spanaway lake and downstream waterbodies.  The lake will be subject to increased algae blooms during the initial phosphorous suspension and there will be a need for in water and on-shore facilities to operate the suspension mechanisms. These may be minimized by timing the suspension activities to low temperature high discharge periods from Spanaway lake.

3)      Periodic removal of lake sediments (the primary reservoir of available phosphorous; B&C report) can be achieved either through significant biomass removal, such as plant harvesting and algae filtering.  Alternatively, a more direct approach would be to removed sediment from easily accessible locations such as shallows around the lake or, more effectively, from the deeper lake basins that contain most of the sediment.  The parameters for either of these approaches are well known and start with collecting substantial amounts of data on the lake flora, fauna and geology.  Fortunately, due to prior studies a substantial amount of this data already exists in Ecology, DNR and Pierce county records.   

Capital Funding Request:

  Our immediate goal is to obtain funding for an Integrated lake management plan consisting of 1) Wildlife survey and management plan, 

2) Aquatic Vegetation Management Plan.

3) Sediment removal evaluation and plan

4) Geological survey of ground water flow and pump& treat feasibility.

Each of these studies will contribute to identifying the best approach (or combination of approaches).  With the information provided it will be possible to obtain permits to implement the overall lake management plan.

Inclusive in this plan would be a pilot program to remove invasive aquatic plant life from the lake. Currently the extent of the problem is unknown but areas of the lake are becoming choked with vegetation from non-native and native plants. Establishing this plan will help us understand the extent of the problem, identify what non-native species are present, the locations and density of growth. It will also help us formulate a plan to deal with them and what the best practices are to eliminate the problem.

FOSL is requesting that Pierce County receive funding to conduct the above studies and develop the requisite plans to control phosphorous and its related adverse effects on Spanaway Lake. Inclusive in this request is a set aside for community organization to participate in the study and provide user education to the broader the lake community.

Recognizing this is a substantial challenge and will take over one year to complete the request is for $###,### in immediate funding with the funding duration to be over two years from study initiation.  This equates to approximately 50 cents per lake user over two year period requested.    

Doing nothing is not an option. Acting now instead waiting for the problem to get worse will improve our chances of success and require less drastic and costly options.  This effort can also provide a model for use on other high use urban waterbodies that are subject to the same environmental pressures.

Sincerely,

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