Utah Lake Watch Report 2008
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Utah Lake Watch Report 2008 Utah State University Water Quality Extension Prepared by: Eric Peterson Introduction Utah Lake Watch (ULW) is a statewide monitoring program which enlists the help of volun teers to ga in ins ig ht on the h ealth of Ut ah’ s l ak es and reservoi rs. Th ese d at a help the Utah Division of Water Quality in their lake protection programs, and provide lake managers with a better picture of the health of their lake. Major objectives of the program include: • acquiring baseline data for Utah’s lakes and reservoirs; • providing education to the citizens of the state on the importance of healthy lakes, how lakes function, and how we monitor lakes; and • demonstrating the effectiveness of citizen monitoring in collecting water quality data which can be used to better manage and protect our lakes and reservoirs. To meet these objectives, Utah Lake Watch participants are trained to measure the transparency of a particular lake or reservoir on a regular basis from May until September. The participants record these readings and weather observations on a data sheet, and return the data to USU Water Quality Extension at the end of the season. USU Water Quality Extension compiles the raw data and delivers it electronically to the Utah Division of Water Quality. In addition, they summarize the results for each lake and return these summaries to the citizen volunteers. All of these results and interpretations are contained in this annual report. Participants measure transparency using a Secchi disk. The measurement itself is very easy; the Secchi disk, which is a white and black weighted disk attached to a line, is lowered into the water until it is no longer visible. The line is pulled slowly back up and the depth at which the Secchi disk reappears is recorded. This is referred to as the “Secchi depth”, which correlates to other indicators of a lake’s health, such as the amount of suspended algae growing in the lake, the amount of nutrients entering the lake , and seasonal patterns of plant growth. The Secchi depth is converted to a Trophic State Index or TSI which is used to classify lake health (see Discussion Section). Results Lake Watch volunteers have been collecting data since 2003. Because we depend entirely on volunteers, not all lakes are monitored each year. In 2008, 16 lakes and reservoirs were successfully monitored. Table 1 provides a list of these lakes and reservoirs as well as the volunteers who collected the data. Since 2002, 42 different water bodies have been monitored. Data from previous years may be obtained by contacting USU Extension. The average 2008 Secchi depth measurements in each water body are displayed in Figure 1. The number of sample collections and range of dates for each lake or reservoir are summar ize d in Ta ble 2. The resu lts for eac h mon itor ing even t in 2008 can be seen in each individual lake or reservoir report. In addition, all data collected in 2008 are included in Appendix A. Table 1. Participant List *Note: Some site coordinates were obtaiobtainedned from DWQ lake and reservoir reports. Lake / Reservoir Site Coordinates Volunteer(s) Bear Lake 1 N 41° 57.900' W 111° 23.333' Scott Tolentino BLk2Bear Lake 2 N41N 41° 1. 46' W 111° 23. 23' PtiPretorius Fam ilily Big East Lake N 39° 56.05' W 111° 38.21' Bruce Childs Causey Reservoir N 41° 17.5' W 111° 35.01' Paul and Nathan Baker Deer Creek Reservoir N 40° 24' 24'' W 111° 31' 33'' Dawn Larsen Mike Enright and Bradon Grantsville Reservoir N 40° 32' 32'' W 112° 30' 13'' Candelaria Hyrum Reservoir N 41° 37.66 ' W 111° 52.015' Floyd Powell Otter Creek Reservoir N 38° 12.52 ' W 111° 59.17' James Lowe Pineview Reservoir 1 N 41° 15.33 ' W 111° 49.28' Keith Rounkles Pineview Reservoir 2 N 41° 15.33 ' W 111° 49.28' Craig Haaser Red Fleet Reservoir N 40° 34.449 ' W 109° 25.448' Mike Murray Mike Enright and Bradon Stansbury Lake N40N 40° 38' 40'' W 112° 18' 17'' Candelaria Starvation Reservoir N 40° 11.465 ' W 110° 26.681' Mike Nealley Steinaker Reservoir N 40° 31.52 ' W 109° 31.29' Mike Murray Utah Lake 1 N 40° 10.588' W 111° 48.290' Allen Palmer Richard Edwards & Adam Utah Lake 2 N 40° 10.588' W 111° 48.290' Peterson Mike Enright and Bradon Vernon Reservoir N 39° 59' 35'' W 112° 23' 15'' Candelaria Willard Bay N 41° 22.461 ' W 112° 07.302' Roland Bringhurst Yuba Lake N 39° 22.281' W 112° 01.890' Chris Evans Average Secchi Depth Lk/RLake/Reservo ir meters) ( 0 1 2 Secchi Depth 3 4 5 6 7 8 Figure 1. Average Secchi Measurement for each lake or reservoir monitored in 2008 by ULW volunteers. The maximum average depth for 2008 was 6.9 m at Bear Lake. The minimum average depth was 0.2m at Utah Lake. The number of samples at each site varied, as well as the dates of collection, see Table 2. Table 2. The number of Secchi depths collected at each site varied, as well as the dates of collection. This table summarizes the number of measurements collected at each site and the months of collection at the site. Number of Measurements Lake / Reservoir Collected Months of Collection Bear Lake 1 9 May-November Bear Lake 2 5 July-August Big Eas t La ke 5 AtAugust-StSeptem ber Causey Reservoir 4 June-August Deer Creek Reservoir 3 June-July Grantsville Reservoir 2 June-July Hyrum Reservoir 14 May-October Otter Creek Reservoir 11 June-September Pineview Reservoir 1 6 July-October Pineview Reservoir 2 4 August-September Red Fleet Reservoir 5 June-September Stansbury Lake 1 JlJuly Starvation Reservoir 22 April-September Steinaker Reservoir 9 May-September Utah Lake 1 6 June-September Utah Lake 2 3 July-August Vernon Reservoir 3 June-August Willard Bay 4 June-August Yuba Lake 6 June-August Discussion Eutrophication, or lake aging, is the natural process by which a lake fills in over geologic time with erosion materials carried by the tributary streams, with materials deposited directly through the air, and with materials produced in the lake itself. The natural process of eutrophication usually requires thousands of years to happen, however, human influence can accelerate the process by altering wetlands and watersheds, shoreline vegetation, discharging sewage into lakes, and improper management of agricultural, development or industrial activities. This is known as cultural eutrophication. Lakes which experience a higggh degree of cultural eutrophication can experience fish kills, excessive aquatic weed and algal growth, loss of game fish, increased treatment costs for culinary water, loss of recreational usage, and other water quality related problems. As a scientific tool, classification can be a practical method useful in lake management. Scientists have developed lake classification schemes based on origin, shape, thermal range, depth, chemical content, dominant types of organisms, and trophic state. Trophic state is an important factor to use when classifying lakes for lake management decisions. This classification is loosely interpreted as the nutritional status of a lake, and can give insight to the productivity and health of a lake. A Secchi depth is only one parameter used in calculating a Trophic State Index (TSI) and caution must be used when evaluating the overall health of a lake based on one type of data collection. Two other parameters can be used to calculate the TSI value; phosphorus concentration and chlorophyll concentration. General water clarity, phosphorus concentration, and chlorophyll concentration correlate with each other. High phosphorus concentrations can stimulate more plant growth (higher chlorophyll concentrations), which can lead to lower water clarity (low Secchi depth). Waterbodies are classified using the TSI index below: Classification Definition TSI Index Value Oligotrophic A waterbody having low turbidity and abundant dissolved oxygen <40 (i.e. good water quality). Mesotrophic A waterbody having moderate turbidity and moderate dissolved 40-50 oxygen (i.e. moderate water quality). Eutrophic A waterbody having high turbidity and low dissolved oxygen 50-70 (impaired water quality). Hypereutrophic A waterbody that is extremely turbid and exceptionally low in >70 dissolved oxygen (i.e. very poor water quality). Table 3. Trophic State Classifications. The average TSI values calculated from the average Secchi depth measurements are shown in Figure 2. Average TSI Value 90 80 70 60 50 40 TSI Value 30 20 10 0 Lake/Reservoir Figure 2. Average TSI Measurements for each lake or reservoir monitored in 2008. For this report, TSI values were calculated using the Carlson equation (Carlson, 1977): TSI = 10(6-log2SD) where SD = Secchi Depth. TSI values less than 40 indicated oligotrophic conditions or good water quality. Lakes and reservoirs are categorized into trophic classifications by various characteristics associated with each lake. In Utah, hypereutrophic classification is used to describe lakes in the extreme eutrophic range. An oligotrophic lake (e.g. Bear Lake) is typically a high elevation lake with low nutrient enrichment, crystal clear waters and rocky or sandy sho re lines, wh er e pl ank toni c an d r ooted pl an t gr ow th ar e spar se, wh er eas a eutr ophi c l ak e (e.g. Willard Bay) is usually high in nutrient enrichment and typically shallower with a soft, mucky bottom, and water clarity tends to be poor and has a coloration. Mesotrophic lakes or reservoirs, an intermediate trophic state, display characteristics between oligotrophic and eutrophic states. According to the ULW data, most waterbodies monitored in the state appear to be mesotrophic (see Table 4 for ULW lake and reservoir classifications) .