Woody Trask 10/21/15
This report summarizes the findings of the 2015 water quality monitoring program for Taylor Pond in Auburn, Maine (MIDAS ID#3750). Secchi disc readings were conducted from June through September. Due to having to send the DO meter out for repair, testing for dissolved oxygen, temperature and other parameters was only conducted monthly from July to September. Additional Secchi readings were taken throughout the summer, with several readings taken to coincide with satellite overflights as requested by VLMP. Since 2004 Taylor Pond Association has been collecting its own water samples and performing most tests. Phosphorus analysis was conducted this year by the DHHS Health and Environmental Testing Laboratory.
Result summary: The results were rather conflicting as the clarity of the lake was quite a bit better than last year and the historical average but the Phosphorus readings were slightly higher and have increased slowly over the past three years. This bears watching as higher levels indicate an increase in the likelihood of experiencing algae blooms. No changes in color, pH, alkalinity or conductance were observed.
The ice out date was April 21. The historical average is April 14.
The results of this year’s monitoring are given below:
|Parameter||2015||Mean for Taylor Pondsince 1975||Historical Mean for all Maine Lakes|
|Total Phosphorous5m core sample, µg/L||11.7vs. 11.5 in 2014||10.1||12|
|Total Phosphorousbottom grab, µg/L||17vs. 15 in 2014||25.3||(not published)|
|Secchi depth (meters) minimum||4.45vs. 4.0 in 2014||1.7 (minimum ever recorded)||0.5(0.9 in 2012)|
|Secchi depth mean (m)||5.48vs. 4.78 in 2014||4.62||4.81(5.2 in 2012)|
|Secchi depth maximum||6.09vs. 5.8 in 2014||6.5 (maximum ever recorded)||15.5(13.4 in 2012)|
|Trophic State (by Secchi disk)||35.5||50.96||45|
|Trophic State (by core Total Phosphorous)||39.6||43.2||(not published)|
* all bottom samples where taken at 12m depth to avoid contamination by bottom sediments
Color: Organic material that remains from dead plants and animals provides most of the water color. Lakes drained by areas with more coniferous forests tend to be brown in color due to the slow degradation of the leaves of these trees. Taylor Pond had a color measured at 20 in 2015, which is slightly higher than the reading of 23 for 2014 and lower than the mean for all Maine lakes of 28. When the color is greater than 25 a lake is considered “colored” and the transparency is reduced.
PH: A measure of the acid-base status of the pond. Taylor Pond had a pH of 7.2 in 2015 which is slightly higher than the mean of 6.82 for all Maine Lakes. Acid rain caused by industrial pollutants can cause the pH in lakes to drop below 6. This drop in pH kills off the healthy zooplankton (microscopic animals) leading to death of fish and overgrowth of algae. The pH of Taylor Pond has been very stable over the years.
Alkalinity: A measure of the capacity of the water to buffer against a change in the pH. Taylor Pond’s alkalinity in 2015 was 20 (the same as last year) compared to a mean for all Maine lakes of 11.9. This indicates that our pond is unlikely to have a problem with acidity. The level of alkalinity in Taylor Pond has remained little changed and is not of concern.
Conductance: Conductance indirectly measures the relative number of dissolved ions in the water — the higher the concentration of ions the greater the conductance. Conductance is used as a rough estimate of the amount of pollutants which usually are present as ions. Although conductance is easy to measure it is not considered highly reliable. Taylor Pond’s conductance for 2015 was 89 compared to a historical mean of 89.9 and a mean of 46 for all Maine lakes.
Total Phosphorous: The phosphorus Measurement of phosphorous provides the most reliable measure of the capacity of Taylor Pond to have an algal bloom. Algae in Maine waters tend to be limited by the phosphorous content of the water. If you provide enough phosphorous algae grows rapidly. Algae cause depletion of oxygen in the water which kills animal life, colors the water green and when it dies creates unpleasant odors. Taylor Pond’s phosphorous was done using a 5 meter core and bottom grab sampling technique. Taylor Pond’s phosphorous this year averaged 11.7 µg/L which is close to the historical mean of 10.1 and slightly lower than the 12 reported for all Maine lakes. It is also below the critical level of 15, at which level one tends to see algal blooms. Lakes are categorized as oligotrophic (low level of biologic productivity), mesotrophic (intermediate) or eutrophic (high biologic productivity) based on how much phosphorous they contain. A lake with a phosphorous of less than 10 is considered oligotrophic, between 10 and 30 is considered mesotrophic and over 30 is considered eutrophic.
Secchi Disk: Secchi disk readings provide the easiest method for measuring the clarity of the water. Algae, zooplankton (microscopic animals), natural water color and suspended soil all reduce the transparency of the water. Algae cause most of the change in transparency in Taylor Pond. The mean transparency for 2015 was 5.48, 0.7 meter higher than last year and significantly higher than the historic average for Taylor Pond of 4.62 and higher than the historical average for all Maine lakes. The higher than normal readings may have been due to the unusually dry summer which resulted in less suspended matter being introduced into the pond.
Trophic State: This is a measure of the biologic productivity of the pond — the higher the number, the more biologically productive the lake and typically the poorer the water quality. The scale ranges from zero to over 100. Ponds in the range between 40 and 50 are considered mesotrophic (moderately productive). Values greater than 50 are associated with eutrophy (high productivity) and values less than 40 are associated with oligotrophy (low productivity). Taylor Pond measured at 35.5 by Secchi Disk readings and 39.6 by phosphorous readings (considered the most accurate). Taylor Pond’s Trophic State as measured by the Secchi disk is lower than the state average of 45.
Dissolved Oxygen Profiles: The amount of dissolved oxygen is measured at one meter depth intervals throughout the summer. Generally down to a depth of 5 meters the oxygen level remains at a high level to sustain all animals. Below 5 meters the oxygen levels early in the summer are high, but as the summer progresses the oxygen levels drop to levels (below 5 ppm) unable to sustain fish and other aquatic animals. Warm water fish (such as Sunfish, Perch, Pickerel and Bass) have no difficulty in Taylor Pond because they stay near the surface where the water is well oxygenated. Cold water fish (such as Trout and Salmon) need the deeper colder water, below 20 degrees Celsius, to thrive. By August, this colder deeper water no longer contains enough oxygen for the fish. In addition to the difficulty for fish, oxygen depletion near the bottom of the pond tends to release phosphorous into the water. This is demonstrated by the higher phosphorous levels found in the bottom grab sample (17 at 12 meters* depth vs. 11.7 for the 5 meter core sample). The oxygen depletion found below 4-8 meters is similar to what we have found in the past and continues to reflect the fragile state of Taylor Pond.
Conclusions: The conclusions remain unchanged from last year. The water quality of Taylor Pond is considered to be average compared to other Maine lakes. The potential for an algal bloom continues to be moderate and has not changed significantly from prior years but shows a concerning upward trend. Taylor Pond remains one of the 181 Maine lakes on the Maine Department of Environmental Protections Nonpoint Source Priority Watershed list. This list contains those lakes considered to be threatened or impaired by nonpoint source pollution from land use activities on the surrounding watershed. In addition the Stormwater Management Law considers Taylor Pond to be a lake “most at risk”.
Taylor Pond fails to meet standards for the highest water quality due to the depletion of oxygen found at depths below 5 meters during the summer. In addition, phosphorous levels remain just below the threshold of 15 which could trigger an algal bloom. Monitoring of Taylor Pond has been conducted regularly since 1975. During this time there has been no consistent trend in the parameters measured. In the years we have been monitoring Taylor Pond ourselves, since 2004, there have been no notable algae blooms.
Because of the shallow depth of the pond (mean depth 17 feet) and low flushing rate (1.34 flushes per year, the number of times the water, on average, empties from the pond) Taylor Pond will likely always remain vulnerable to phosphorous loading and therefore algal blooms. Because of oxygen depletion of deep water during the summer, the pond will likely never sustain a cold water fishery. In addition, the oxygen depletion at depths below 5 meters releases an increased amount of phosphorous to the water. Finally, each new structure or expansion of an existing structure, whether a home, garage, driveway, road, lawn or beach, increases the phosphorous loading of the pond.
Taylor Pond continues to have many attractive qualities. The shallow depth means that it quickly warms in the summer to provide excellent swimming close to the towns of Auburn and Lewiston. It freezes quickly in the winter to provide skating, skiing and ice fishing during the winter. It has an abundant bass and pickerel population that thrives in its warm waters and attracts people who enjoy fishing. The Department of Marine Resources considers the pond to be prime spawning habitat for Alewives and trucks adult fish above the dams on the Androscoggin River into Taylor Pond. It has a naturally high level of biologic productivity that sustains an abundant wildlife population for all to enjoy. It remains a place that never ceases to astound us with its beauty.
METHODS: Samples are collected near the deepest point in the pond. This point has been determined previously and the historic location has been noted on maps available to the samplers. This spot is reached by boat and verified each time by visual triangulation for Secchi disk readings. In addition to visual triangulation an ultrasound depth meter is used before collecting core and grab samples. Grab samples are taken using a Van Dorn Water Sampler. Core samples are taken with a core sampler home-manufactured from a 50 foot flexible PVC tube. The method for grab samples at a specified depth and core samples are done according to the protocol of the Maine Bureau of Land and Water Quality, Division of Environmental Assessment.
COLOR: Performed on core samples using a Hach color wheel (CO 20-100) and units are in Standard Platinum Units (SPU).
PH: Performed on core samples using a Hach Bromothymol Blue test kit for pH.
CONDUCTANCE: Performed on core samples using a HM Digital, Inc. Model COM-100 water quality tester for EC/TDS/Temp. Conductivity is measured in uS/cm.
ALKALINITY: Performed on core samples using a titration method with a Hach color wheel measured in milligram per liter.
PHOSPHOROUS: Performed on core samples and bottom grab samples. Samples are collected in the field, refrigerated and sent to the DHHS lab by mail. Measurements are in parts per billion (ppb). The results are the average of four samples taken once a month from June to September.
SECCHI DISK: Performed using the method taught by the Maine Volunteer Lake Monitoring Program. Only certified users performed this task. Measurements of depth are in meters.
DISSOLVED OXYGEN: Performed in the field using a YSI 550A DO meter with 50 foot probe which measures temperature and dissolved oxygen from the surface to maximum depth. The sampler and meter is yearly certified by the Maine Volunteer Lake Monitoring Program as to method and accuracy. Measurements of dissolved oxygen are in milligrams per liter (mg/l). Water temperature at each depth tested is also recorded.
TROPHIC STATE: Carlson’s Trophic State Index (TSI) is used in these calculations. For Secchi disk depth TSI = 60 – 14.41 x (Natural Log of Secchi disk depth in meters). For total phosphorus TSI = 14.42 x (Natural Log of total phosphorous) + 4.15.