Ten Mile Lake Total Watershed Preservation - A Demonstration Project
I. Introduction. Ten Mile Lake (11-0413-00) is one of the most unusual and one of the most completely studied lakes in the state of Minnesota. It has a surface area of 5,047 acres, 21.8 miles of shoreline, and a maximum depth of 208 feet, making it the third deepest inland lake in the state. Supplied by springs and groundwater flow, it stands at the head of the Boy River system, which flows through a chain of 15-16 lakes before emptying into Leech lake. Ten Mile Lake has a relatively small lakeshed, comprising 17,655 acres (including the lake area)(2008 Ten Mile Lake Lakeshed Assessment - RMB Environmental Laboratories). The lakeshed:lake area ratio is 3.5:1.
Ten Mile Lake consists of a large main lake basin and several distinct bays, which are ecologically quite different from the main basin. It is an oligotrophic lake; over the past decade it has measured in the 37-38 range on the Carlson Trophic State Index according to determinations by Instrumental Research Inc., a private firm employed by the Ten Mile Lake Association (TMLA) since 1994 to monitor water quality of the lake. Water quality is very good; mean Secchi disk readings over the past decade have been approximately 21 feet. The lake contains sufficient dissolved oxygen below the thermocline to support fish life. Because of its great depth it has a relatively small littoral area (26%), but yet the lake contains a surprisingly large diversity of aquatic vegetation according to a recent DNR survey (ref.). One of the unique characteristics of the lake is an enormous population of dwarf ciscoes, a cold water species of fish that is being used statewide as a prime indicator of lake water quality. To date, it contains no documented invasive species. Water residence time estimates have ranged from 13-23 years. Ten Mile is classified as a general development lake.
Ten Mile Lake is located in the Northern Lakes and Forests Ecoregion. Its lakeshed region consists of 31% open water, 32% private land and 37% of protected public land. The 32% private land is subdivided as 3% developed, 2.5% agriculture, 22% forested uplands, 4% wetlands and 0.5% open pasture/grassland. The lakeshed, as well as the lake itself, falls within four townships. The Minnesota Department of Administration Geographic and Demographic Division projects that the populations of these townships will grow from 11-43% over the next 25 years. The 2008 Ten Mile Lake Lakeshed Assessment by RMB Laboratories lists shoreline restoration, wetlands restoration and forest stewardship planning as potential future steps in dealing with the lakeshed.
The Ten Mile Lake Association, first formed in 1946, is a very active one. Its membership consists of 625 family units, which is more than the total number of cabins on the lake. For several decades, volunteer members of the TMLA have been involved in many aspects of lake quality monitoring (Secchi readings, temperature and oxygen profiles), shoreline improvement and conservation of land around the lake. The Association has purchased or been donated seven parcels of environmentally sensitive land around the lake and is actively engaged in other projects designed to maintain the quality of the watershed. The TMLA has a comprehensive program of septic system monitoring, with one third of all septic systems around the lake tested each year on a continuous rotating basis.
II. Broad Goals of the Program. Minnesota lakes are confronted with two broad sets of issues. One is to restore lakes that have already suffered significant environmental degradation; the other is to maintain the quality of lakes that have not already been subjected to significant degradation. Ten Mile lake falls into the second category. The overall goal of this program is to use Ten Mile Lake and its surrounding lakeshed as a demonstration project to determine the scope of resources, both human and financial, needed to maintain or even improve the quality of a lake that has experienced relatively little detrimental environmental impact. (Actually, the lake has experienced significant improvement in the past three decades due to the activity of its lake association and the cooperation of the lakeshore residents.) Because of the large amount of data already collected on the lake by a variety of governmental and private agencies and its present inclusion as one of the 22 Sentinel Lakes in the state, Ten Mile Lake is well positioned to serve as a major reference standard for monitoring long-term environmental effects on Minnesota lakes. At a local level, preservation of the overall quality of the lake and its watershed is a principal long-term broad goal of the TMLA.
III. Specific Program Goals. The overall project is a complex one that involves a number of interdigitating individual components. Some represent a continuation or modification of existing activities. Others are new. Specific goals are laid out in this section. The next section (IV) outlines what will be necessary to achieve these goals.
Goal1. Long-term, continued monitoring of key indicators of lake water quality.
A. Water clarity
B. Water chemistry (phosphorus, nitrogen, chlorophyll a)
C. Water temperature profiles
D. Dissolved oxygen profiles
E. Wetland water run-off into the lake
F. Fish populations
G. Exotic species
H. Aquatic plants
I. Shoreline birds, reptiles, amphibians
Goal 2. Increase restoration of degraded shoreline and maintenance of natural shoreline.
Goal 3. Change lake classification and zoning to reflect intralake zoning recommendations.
Goal 4. Increase land purchases and conservation easements on privately owned land.
Goal 5. Improve management of wastewater from private dwellings around the lake.
Goal 6. Implement aerial survey of vegetation in lakeshed.
Goal 7. Analyze and monitor groundwater flow in lakeshed area.
Goal 8. Monitor key atmospheric data in lakeshed area.
Goal 9. Maintain ongoing database on lakeshed use and ownership.
Goal 10. Implement system for long-term evaluation of quality of lake and lakeshed and of the
cost and effort involved in preserving or improving it.
Goal 11. Publication and dissemination of collected data.
IV. Plans for Achieving the Above Goals (To be filled for specific grant applications)
V. Partnerships Required for This Project. A comprehensive project like that outlined above cannot be achieved by any one organization or element operating alone. Table 1 summarizes some of the partnerships that will be necessary in order to achieve the goals of this project. In reality, many of our potential partners in this project are governmental agencies with well defined operational and jurisdictional boundaries. It would be extremely rare for any single private or governmental agency to have a purview or the resources broad enough to cover a multidisciplinary program such as this one. In order to be successful, this project will necessarily involve considerable on-the-ground effort by members of the TMLA in addition to the financial and technical support of a number of different private and governmental agencies. However, understanding and documenting the total effort to maintain the quality of a watershed is actually a significant component of this project.
VI. Preliminary Data, and What the TMLA Can Contribute to This Project. Two of the strengths of this proposed program are the large amount of data up to the QA/QC standards adopted by governmental agencies that has already been gathered on critical aspects of Ten Mile Lake itself and the level of volunteerism among lake residents. Much of the past data has been consolidated into a database compiled by the Healthy Lakes Committee of the TMLA (reference). In addition to historical data gathered through lake surveys and creel census surveys conducted by the DNR, there are separate sets of data gathered by the MPCA, the USGS, Instrumental Research, Inc., and the TMLA on various aspects of the lake. These include Secchi disk readings, water temperature and dissolved oxygen profiles going back to the 1970s (all collected by lake resident volunteers) and a multitude of formal studies by governmental agencies. There is a continuous database of water chemistry readings collected and analyzed three times per year by Instrumental Research, Inc. since 1994. This company is retained by the TMLA. A partial list of previous studies on the lake is given in Appendix 1.
The TMLA is committed to continue these ongoing studies, and it has the financial resources and interest by lakeshore residents to continue supporting these efforts. The high percentage ( %) of lakeshore residents who are members of the TMLA is an indication of the interest that the cabin-owners have in maintaining the quality of the lake. Members of the TMLA are active participants in other regional organizations, which enables the TMLA to keep abreast of ongoing developments of relevance to the Association. In addition, the TMLA has retained a watershed coordinator, John Alden, who maintains contact with a number of local governmental officials and agencies.
VII. Evaluation of the Success of Individual Projects and the Program as a Whole. The ultimate indicator of the success of this proposed program is the health of Ten Mile Lake, as measured both objectively and subjectively. Evaluation of a complex program such as this is multidimensional and involves different modes of evaluation. Because this program is designed to demonstrate how to maintain an already pristine watershed, a measure of success will be how little individual data points have changed from historical values over the years or, particularly, if any improvement has occurred.
The most fundamental measures are quantitative ones, such as the Carlson Trophic State Index and individual components, such as mean Secchi disk readings, phosphorus, nitrogen and chlorophyll a determinations, and dissolved oxygen readings below the thermocline. The general principle is to use existing data as a baseline and to determine whether significant changes to particular variables, ranging from lake chemistry to the presence and distribution of plants and animals, have occurred over a defined period of time. At another level, one can quantify the proportion of lakeshore residences that have embarked on shoreline restoration projects over a given period of time and changes in the percentages of lakeshore families that belong to the TMLA. Another measure would be a survey of lakeshore resident satisfaction with the condition of the lake and its watershed, but to be done effectively, such a survey would have to be very well constructed and administered by professionals.
VIII. What Can We Gain and Learn from This Program? At a very specific local level, this program could result in the maintenance of the overall environmental and recreational quality of a lake in which these properties have been remarkably well preserved and even improved over recent decades. At a more general level, however, this program could provide a template for how to maintain or improve the quality of other important lakesheds in the state. Although Ten Mile Lake is somewhat unusual in the degree to which the entire lakeshed is insulated from a variety of external influences, the relative simplicity of this system lends itself to a quantitative approach that would be lacking in a similar program conducted on other lakesheds. One of the most important principles resulting from a successful program would be that it is truly possible to maintain the overall quality of a lake and its lakeshed while yet allowing a reasonable amount of prudent use of the area. From well-designed projects, it should be possible to estimate the total cost in terms of both dollars and effort. Another critical element of such a demonstration project would be an assessment of the degree of compliance, cooperation and buy-in by residents of the lakeshed that would be necessary for such a program to be successful. Perhaps even more important would be the level of participation and interaction required of governmental agencies at various levels in order for such a program to function properly. Another critical part of the overall program is an review/action plan that follows up changes in indicators that may have positive or negative effects on the overall quality of the lakeshed.
IX. References.
X. Appendices.