Stewardship groups, governments and regulatory agencies all have roles to play in the long-term management of watersheds. Watersheds are complex systems as described in State of the Watershed reports. Obviously many factors must be considered when making decisions about the future.
Using decision support tools to connect watershed variables and indicators to management goals can help to simplify problems and to identify, rank and select the most important indicators.
The linked presentation explains how the Sylvan Lake Watershed Stewardship Society has applied decision analysis to evaluate goals, set priorities and evaluate the effect of massive population expansions that are proposed in the development plans of the Sylvan Lake watershed municipalities.
This post contains reference material prepared for the Cumulative Effects Management System project which is a joint effort of member municipalities of the Sylvan Lake Management Committee and the Alberta department of Environment and Sustainable Resource Development.
Marion Thompson, the volunteer office manager at the Sylvan Lake and District Archives Society invites residents to view the old photos, maps and documents at the location noted on the following brochure:
Marion Thompson can be reached by email at: email@example.com or by telephone at (403)-887-6296.
Sylvan Lake exists because the last ice age created the watershed basin and because today the amount of water that enters the watershed is about the same as the amount that leaves it. The following diagram shows the inputs and outputs of water that determine the lake level and its fluctuations from year to year:
Water Balance for Sylvan Lake (AXYS 2005)
The inventory of water in the Sylvan Lake watershed is controlled by the balance between input precipitation and losses by evaporation and export. According to the analysis of multi-year data presented in the AXYS 2005 report the lake annually receives about 20 million cubic metres (Mm3, or tonnes) of precipitation. Surface runoff adds about 11 Mm3 and subsurface groundwater flow contributes about 3 Mm3 of water.
The major loss of 31 Mm3 is by surface evaporation. Stormwater diversion easterly to Cygnet Lake and overflow through the Outlet Creek removes about 3 Mm3 of water.
Hot dry summer months accelerate evaporation and the historic record shows that the lake level can drop by up to one foot within a few weeks. Periods of cool weather and high precipitation reduce the evaporation rate and raise the lake level. In the future, increased well water extraction of groundwater for domestic use combined with pipeline export downstream to Cygnet Lake and then on to the Red Deer River has potential to disrupt the Sylvan Lake water balance. In addition, increased collection and diversion of stormwater outside the watershed by the Town of Sylvan Lake will reduce the volume of surface water entering the lake.
The figure above also includes data from the AXYS 2005 report on the input of the plant nutrients nitrogen (as the analysis Total Nitrogen, TN) and phosphorous (Total Phosphorus, TP) both of which can cause the undesirable growth of algae in the lake.
Because the concentrations of nitrogen and phosphorous (N and P) plant nutrients are low in Sylvan Lake, algae growth in the lake is minimal and the lake clarity is high. The details are reported in the Blindman River chapter of the Red Deer River Watershed Alliance master summary of the State of the Watershed.
Since shoreline property development started at Sylvan Lake decades ago the riparian zone adjacent to the lake has changed. Government surveys classify much of that zone as “impaired”. Property owners can help to restore some riparian zone functions by looking critically at landscaping and structures with the goal of improving water balance and reducing nutrient transfer into the lake. Simple actions like not applied fertilizer close to the lake edge, or mowing lakefront lawns that border the lake, are important.
Opportunities and potential experimental shoreline sites are limited for a variety of reasons including water depth. However the Sunbreaker Cove SV has AESRD approval for a shoreline stabilization project that might include the use of aquatic plants to minimize erosion.
In general, property owners who apply to AESRD to modify the shoreline are advised to consider those techniques in combination with rip-rap installation.
Resources and advice on shoreline protection are readily available: