Cleaning up Elk and Beaver Lakes: What Can Be Learned from Other Lakes
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Mu rray & Anne Fraser Building PO Box 1700 STN CSC Victoria, BC V8W 2Y2 Phone: 250.721.8188 Em ail: [email protected] Web: www.elc.uvic.ca Cleaning Up Elk and Beaver Lakes: What Can be Learned from Other Lakes Prepared for the Victoria Golden Rods and Reels By Roisin Lyder, Law Student with Erin Gray, Articled Student Supervised by Calvin Sandborn Summer 2015 I. Purpose .............................................................................................................................................. 1 II. Introduction .................................................................................................................................... 2 III. Case Studies ................................................................................................................................... 3 1. Technical Solutions: Aeration, Dredging, Alum ............................................................................. 3 1.1 Aeration .................................................................................................................................................................. 3 1.2 Dredging ................................................................................................................................................................. 7 1.3 Alum ......................................................................................................................................................................... 9 1.4 Harvesting Problematic Species................................................................................................................ 13 1.5 Summary and Recommendations – Technical In-Lake Solutions ............................................... 15 2. Input Management: Waste Water, Changing Behaviours, Wetlands .................................. 15 2.1 Waste Water (Septic) ..................................................................................................................................... 16 2.2 Changing Behaviours (through Public Education or Regulation) ............................................... 18 2.3 Constructed Wetlands ................................................................................................................................... 20 2.4 Summary and Recommendations – Input Management ................................................................. 22 3. Collaborative Governance over Lake Problems ......................................................................... 23 3.1 Summary and Recommendations ............................................................................................................ 27 IV. Summary/Next Steps ............................................................................................................... 28 1 I. Purpose Water quality in Elk and Beaver Lakes has been seriously declining since at least the early 1980s. These lakes are enormously important to Victorians, with close to two million visitors to the regional park in a given year. The lakes have traditionally been very popular with recreational users for fishing, swimming, and rowing. The lakes’ water quality has now become unacceptable. Elevated levels of nutrients such as phosphorus are causing a variety of problems. Blooms of potentially toxic cyanobacteria have become increasingly frequent. The Capital Regional District has posted signs for people and dogs to avoid the water during blooms. For the past two years, authorities have moved the Polar Bear swim to Thetis Lake because of the algae risk at Elk Lake. Excessive nutrients also exacerbate dense growth of aquatic weeds – which is problematic for rowers and anglers and dangerous for swimmers. Fishing success has declined in recent years, and invasive species such as bullfrogs and exotic fish have occupied the lakes. The two largest external sources of nutrients are septic tanks and agricultural runoff coming from surrounding creeks. However, the main source of the nutrients is now internal, coming from sediment located at the bottom of the lake. Such nutrient- related problems are not unique – eutrophication is occurring in many southern Vancouver Island/Salt Spring Island lakes. Efforts are now underway to identify a process to deal with Elk and Beaver Lakes’ water quality. Concerned conservation groups are considering solutions such as measures to: Reduce nutrients into lake, by: o Controlling stormwater runoff; and o Controlling septic runoffs through better regulation and monitoring of septic fields; Implement a 20-year-old Park Management Plan that called for aeration of the lakes, and other measures to improve water quality; and Treat the lake by adding alum or other materials, and other measures. However, an overall plan to implement solutions has not yet been developed, since jurisdiction over the lakes is extremely fragmented. For example, Vancouver Island Health Authority has jurisdiction over human health and water testing issues; the District of Saanich has authority over land use/sewer/stormwater issues; the Capital Regional District has jurisdiction over septic tank inspections and implementation of the park management plan; the Province has jurisdiction over many water, fisheries and dam issues; and the federal government has jurisdiction over boating regulations and salmon fisheries issues in the watershed. This paper intends to describe solutions from other jurisdictions to inform a fulsome study into a long-term management plan for Elk and Beaver Lakes. 2 II. Introduction Every lake is unique. Specific strategies to address a lake's nutrient enrichment problems must focus on activities in the watershed and, if needed, in-lake restoration techniques. Long-term management considers the environmental, cultural, and biological factors affecting the lake and sets a priority on finding lasting solutions. Lake management is complicated and requires a coordinated effort of community groups, individuals, landowners, and government – and must involve scientific experts. To be effective, lake managers must commit to long-term strategies and investment. There is a direct relationship between the amount of phosphorus in a lake and the amount of algae growing in the lake: as phosphorus levels increase, the amount of algae increases too. “Algal blooms,” which are rapid increases or accumulations in the population of algae in a water system, may result. The increased nutrient levels result in the state of “eutrophication.”1 This increased nutrient load and subsequent increase in algae results in a depletion of oxygen. Once a lake reaches very high levels of phosphorus, other nutrients may limit the growth of algae. However, long- term management of excessive algae requires the removal of phosphorus sources to the water body as well. This is referred to as “input management.” However, for the best chances of success, a combination of efforts to control nutrient sources through input management as well as in-lake restoration techniques is required – and there are a number of options available. In determining how to approach cleaning up Elk and Beaver Lakes, it is useful to investigate some case studies of other lakes that have successfully dealt with or have been dealing with similar problems – and glean from those some best practices in lake restoration. This report investigates the following four main topics and includes other lakes as case studies under each topic heading: 1) Technical Solution → what was used to deal with the elevated nutrient level in the water body? 2) Input Management → What efforts were made to deal with septic/agricultural runoff or sewage? 3) Involvement → who was involved in making the cleanup happen? How were multi-jurisdictional and multi-stakeholder issues handled? 4) Public education → Was the community mobilized to participate? 1 Eutrophication is the ecosystem's response to the addition of artificial or natural substances, mainly phosphates, to an aquatic system One example is the "bloom" or great increase of phytoplankton in a water body as a response to increased levels of nutrients. 3 III. Case Studies 1. Technical Solutions: Aeration, Dredging, Alum As mentioned, in many cases, it is not possible to immediately improve lake water quality by input management (controlling the nutrient sources of phosphorus). Frequently, many years will pass before a lake cleanses itself of accumulated nutrient loads, even with the application of the best input management practices. For this reason, in-lake restoration techniques have been developed to accelerate the recovery of lakes suffering from eutrophication. The suitability of each technique to the lake in question will vary, and each technique may not work for all lakes and all conditions. Implementation of any of these technical solutions should only occur after a lake specialist has evaluated the lake and recommended one or more of the options. 1.1 Aeration The technique of aeration involves pumping oxygen into the deep, nutrient- enriched, oxygen-depleted layer that forms in deeper lakes called the hypolimnion. The goal of hypolimnetic aeration is to maintain oxygen levels in this layer, as this will limit phosphorus release from the bottom sediments. From: Washington Department of Ecology, “Algae Control Program” (accessed 23 October 2015), online: <http://www.ecy.wa.gov/programs/wq/plants/algae/lakes/LakeRestoration.html>. Aeration can improve habitat and fish populations by improving their food supply by providing more oxygenated waters. While several local lakes have