Wisconsin Department of Natural Resources / / University of Wisconsin – Extension Lakes Wisconsin Association of Lakes Source: USGS Wisconsin Lakes Partnership Science Citizens Education Water Clarity Monitoring through the use of the Secchi Disc Factors we cannot control Time of day (10am-4pm): Secchi values vary by about 6% due to solar altitude changes in mid summer (over May-Sept. this increases to 15%). Waves – sometimes we have to make due with mother nature. 5” waves can decrease reading by 10%. Surface reflections off the water. Observer vision characteristics. Factors affecting Secchi readings Factors we cannot control Secchi values vary due to solar angle and earth’s tilt over the summer Waves – sometimes we have to make due with mother nature. Surface reflections off the water Observer vision characteristics Factors we can control Time of day Monitoring day conditions (monitor on sunny calm days) Follow protocols Increase number of readings (duplicate or triplicate readings) SECCHI READING SUMMARY SHEET 1.Contact your Citizen Lake Monitoring Network Coordinator for volunteer identification number, waterbody identification number and station identification number. Station identification number identifies the sample site on the lake, usually the deepest part of the lake (the deep hole). 2.Before going out to collect secchi reading, be sure that conditions are right and safe for sampling 3.Sunny to partly sunny/cloudy skies 4.Wind calm to breezy – there should be no white caps on the lake 5.Between 10:00 am and 4:00 pm 6.Gather your reporting form, lake map with the sample site marked, PFD and secchi disk. Motor to the deep hole or other designated sampling site. Anchor boat. 7.Mark time and date on your data sheet 8.Remove sunglasses. Secchi reading is taken from the shady side of the boat. 9.Unwind the secchi disk rope from the holder. Lean over the shady side of the boat and slowly lower the secchi disk into the water until you can no longer see it. Ideally you should be as close to the surface of the water as is safe. If you are sampling from a pontoon boat, be sure to kneel down on the floor of the boat. 10.When the secchi disk barely disappears from view, mark the rope at the water level with a clothes pin. 11.Lower the secchi disk a few more feet into the water. Slowly raise the disk. When the secchi disk reappears, mark the rope at the water level with the second clothespin. The clothespin may be at the same spot or there may be several inches difference. 12.Bring the secchi disk back into the boat. Average the two secchi readings by forming a loop between the two clothespins. Slide one clothespin into the center of the loop to mark it. Remove the other clothespin. The remaining clothespin will be your secchi reading. 13.Count the number of feet from the disk until you reach your clothespin. Round off to the nearest quarter foot and record that number on your data sheet. 14.Complete water aesthetics survey on your worksheet. Water level should be recorded using the ordinary high water mark as the norm. 15.To determine if the water appearance is clear or murky, hold your secchi disk one foot under the surface of the water and observe how the white part of the disk appears. 16.To determine water color, hold your secchi disk one foot under the surface of the water and observe the water against the white of the disk. Clear water should be recorded as “blue”. 17.Indicate your perception of the water quality at the deep hole. On a scale of 1 to 5 (1 being the best and 5 being the worst) record your perception of the amount of algae in the water. 18.Record weather and other observations. Ways to minimize variations Time of day (10am-4pm) – If readings taken outside this 6-hour time frame, we increase the variability. Waves – Monitor on calm days. Surface reflections – use shady side of the boat. Clearness of the sky – Monitor on sunny to partially sunny days. Remove your sunglasses. Position your body as close to the water as is safe. Observer vision characteristics – make sure to match the observer’s name with his/her readings Following descending/ascending (2 cloth pins) protocols. Variability in readings is less when averages are taken as compared to just taking a descending or ascending readings. (Worst case was 1-meter between either ascending or descending reading and average of the two. Luckily, only 4.5% of samples were more than 0.5 meters different than the average). Secchi depth can change up to 17% of the max Secchi depth if averages are not used. The % of difference can be important for assessment purposes and will be more important for lakes with low Secchi depths. Feel free to repeat measurements – We gain accuracy with repetition. Source: Sandy Wickman Wisconsin Citizen Lake Monitoring Network Secchi Quality Assurance / Quality Control worksheet Waterbody # ___________ Storet # ___________ Lake Name _________________ County _______________ Year __________ Volunteer nameDateTimeSecchi Depth. 1st descending reading.Secchi depth.1st ascending reading.Secchi depth.2nd descending readingSecchi depth.2nd ascending readingSecchi depth.3rd descending readingSecchi depth.3rd ascending reading.Sum of 6 secchi readingsAverage of 6 readings (Sum ÷ 6)Hit bottom?1=yes 2=NoLake level1=high, 2=low, 3=normal, 4=gaugeLake level, if gauge enter numerical levelAppearance1=clear, 2=murkyWater color1=blue, 2=green, 3=brown, 4=red, 5=yellowPerception 1-5 Return filled out form to Laura Herman, UWEX-Lakes 107 Sutliff Ave, Rhinelander, WI Amy, I have a “form” that I want added, It has the below information with more rows and columns....It is in Word, but will not take hold. Make sure to put in the link to the manual under the manual photo