Secchi Day 2017 Results

by: Angela Danovi, Arkansas Regional Projects Manager

Earlier this year we wrote about Secchi Day on Beaver Lake, an annual volunteer citizen science event held to document water quality trends in Beaver Lake.  Around the same weekend each August, Beaver Water District hosts Secchi Day on Beaver Lake, a citizen science program that allows volunteers to get on the lake to take secchi readings and collect water quality samples which are analyzed  for chlorophyll-a, total phosphorus, and nitrates. Staff at Beaver Water District analyze the samples in their certified lab and compile the data into a report describing the annual results and long-term trends of water quality in the lake.  In mid-October, Beaver Water District released the 2017 Secchi Day report.  The results  indicate most water quality parameters were fairly close to the 12-year average found from all Secchi Day data. The average lake Secchi depth this year was around 9 feet, which is slightly higher than the long-term average of 8.8 feet. The average lake chlorophyll-a this year was 6.39 parts per billion (ppb), which was slightly lower than the longer term average of 7.32 ppb.  Both of these values point to 2017 as being a year with better than average water quality.on Beaver Lake, indicating we are generally maintaining our water quality in Beaver Lake, the drinking water source for Northwest Arkansas.

Matthew Rich, Environmental Specialist with Beaver Water District said “after 12 years of collecting data, we are finally getting a picture of the variability in water quality at the different sites.  On Beaver Lake, as you travel from Hwy. 412 bridge to the dam, chlorophyll-a decreases and Secchi transparency increases. This is because as water moves through the lake, nutrients are used up and suspended particles like sediment and algae fall to the bottom, making the northern part of the lake less productive.”  there are a lot of factors that play into numbers in any given year and the amount and timing of rainfall is one of the largest contributors.  Rainfall totals in June, July and August of this year were 7.5 inches, which was approximately 17 inches below average.

Graphs and maps, below, depict the 2017 Secchi Day Results.

 

Please click here to access the complete 2017 Secchi Day Report

Secchi Day 2017 Results

Secchi Depth:

The maximum depth at which a Secchi disk can be viewed from the surface of the water

  • Maximum Secchi Depth -19.68 feet at the Beaver Dam
  • Minimum Secchi Depth – 0.65 feet at the Confluence of White River and Richland Creek

 

Chlorophyll-a:

A pigment in algae that is used to measure the density of the algal population of the lake.

 

  • Maximum Chlorophyll-a concentration – 20.01 ppb at White River arm near Hwy 412
  • Minimum Chlorophyll-a concentration – 2.03 ppb at the Big Clifty Recreation area..

 

Total Phosphorus:

A nutrient that promotes algal growth. Phosphates come from a variety of sources including agricultural and urban runoff, sewage treatment plant effluent, and faulty septic systems.

  • Maximum Total Phosphorus Concentration – Confluence of White River and Richland Creek
  • Minimum Total Phosphorus Concentration – < 10 ppb at many sites

 

Nitrate:

A nutrient that promotes algal growth. Nitrates also come from a variety of sources including fertilizer runoff, faulty septic systems, municipal wastewater and sludge, and erosion of natural deposits.

 

  • Minimum Nitrate – < 30 ppb at multiple sites from War Eagle to Rocky Branch
  • Maximum Nitrate – 434 ppb at the confluence of White River and Richland Creek

 

One thought on “Secchi Day 2017 Results

  1. Megan York

    Congrats on having better than average water quality this year! Your citizen science monitoring program sounds very effective. Your area is lucky to have that in place.

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