Executive Summary 2003
Adirondack Watershed Institute
This report presents the findings of the 2003 monitoring program for the Rainbow Lakes (Rainbow Lake and Clear Pond). The report includes an executive summary, a description of the monitoring methodology, a summary of results for each water quality parameter, an analysis of water quality trends, conclusions and recommendations. A glossary of lake and watershed terms is presented in Appendix A. All water quality data are presented in Appendix B.
The Adirondack Watershed Institute (AWI) sampled two main stations, one each on Rainbow Lake and Clear Pond, once per month from June through August 2003. AWI performed additional monitoring at several other locations each month in order to test for water quality degradation resulting from shoreline areas that contained a concentration of camps.
Both Rainbow Lake and Clear Pond continue to be mesotrophic. Water quality
conditions in Adirondack lakes & ponds were dominated by the weather again during 2003. Although the temperature averages for this year through this time seem to indicate a more “normal” year, this can be deceiving at first glance. Last winter was one of the coldest on record dipping down to -28.5 degrees Fahrenheit. To make up for this, this past summer was one of the warmest on record. So, if we look at the yearly averages, they would show us a normal Adirondack year. The amount of precipitation especially varied from the norm. We are presently in drought like conditions. According to the National Weather Service we are presently nine inches of precipitation below where we should be for this time of year. If we look at May through August we received 11.85 inches of precipitation. This is the usual amount we should receive for just May and June and this was the wettest part of the last year. The remainder of the year, we received just 5.83 inches of precipitation scattered over five months. These later summer conditions are similar to drought-like conditions experienced in 1999 and 2001, which affected the lakes as such. As a result, the following was generally observed in the 2003 lake studies: higher pH and alkalinity values; higher color, lower total phosphorus and chlorophyll a values, and high transparency.
Rainbow Lake exhibited much lower chlorophyll a levels, slightly higher total phosphorus concentrations and much higher transparencies in 2003 than in 2002. Clear Pond exhibited lower chlorophyll a levels and lower total phosphorous concentrations than in 2002 but these were still elevated over most other years. This resulted in higher transparencies in 2003, but again transparencies were still lower than most other previous years. Color levels were much lower in Rainbow Lake and Clear Pond during 2003 showing the lack of runoff from the surrounding wetlands for both of these study lakes.
We now have a good historical record of dissolve oxygen profiles for Rainbow Lake dating back to 1954. We can use theses profiles for comparative purposes and we can draw some conclusions from almost fifty years worth of historical data. The historical dissolved oxygen data does show that the oxygen deficit in Rainbow Lake began to show itself in July by 1984. This deficit has intensified during the 1990's and has become worse every year over the last five years, except for 2002. This deficit could be caused by human impacts around Rainbow Lake from the 1960's, 1970's, 1980's or up to present day.
Overall, the data does suggest that humans have definitely influenced Rainbow Lakes’ water quality in the past. The only way to tell if humans are still causing a continued decline in Rainbow Lakes’ water quality and drop in dissolved oxygen is to continue to monitor next year and the years to come to see if the trend reverses itself. If this trend does continue Rainbow Lakes’ water quality will continue to decline and human impacts should be looked at very closely.
Rainbow Lakes Association should continue to be concerned about the possible water quality impact of old and substandard septic systems. Efforts should be taken to require system upgrades as much as is reasonable and practical. Septic system testing and crude mapping of all systems should be performed on all camps located on Rainbow Lake and Clear Pond if it has not been done in the last ten years. In general, routine dye testing will only locate systems that either have straight pipes into the lake or are grossly failing (broken pipes or systems located within the groundwater table). We do not recommend annual testing of septic systems. However, since it may have been some time since these systems have been tested, we recommend a routine dye test screening on every system around the lake. We also recommend that crude maps of the systems be performed. This would include questions on usage of the system and the system could be mapped by G.P.S. receiver for future use.
The only cost-effective way to perform this type of screening is with the cooperation of the lake camp owners and association in order to schedule the testing over several days. The dye testing should be performed after the homes have been occupied for some time during the summer season, preferably after but not necessarily during a busy, holiday weekend such as the Fourth of July. In a routine dye test screening, fluorescent dye (fluoracein or Rhodamine) is flushed down a toilet in every camp. Boathouses with bathrooms and any other systems should be tested separately. The shoreline in front of the camp or boathouse is then observed for the appearance of visible dye. With proper scheduling, it should be possible to test all of the systems around the lake during a short time period. Once a screening has been performed to identify acute failures, it should not be necessary to repeat the dye test annually.