(1) The relatively pristine upper basin streams are in good condition;
(2) San Antonio Creek is characterized by excessive nitrogen;
(3) Locations below the WWTP exhibit excessive concentrations of both nitrogen and phosphorus, although nitrogen values are not as high here as those on San Antonio;
(4) Nitrogen on the middle Ventura straddles the line between acceptable and poor, while phosphorus remains low; and
(5) In general, excessive nitrogen is a much larger problem than excessive phosphorus.
The list above summarizes the findings in a report issued this week by Al Leydecker, Ph.D., Santa Barbara Channelkeeper’s technical advisor. The report analyzes nutrient concentration data from the Stream Team’s Ventura River watershed monitoring sites from 2008 through 2011.
The 15-page report examines trends in nitrogen peaks; describes interesting interactions between surface water and groundwater; and discusses dry-season nitrogen sources, where the high concentrations are, likely nutrient contributors, the affect of winter-rainfall peaks on concentrations, the importance of the nitrogen-to-phosphorus ratio to freshwater life, factors that contribute to the amount of algae in the river, and more.
The chart above summarizes key data from the report, and here is how Al instructs us to read it:
“Any sample below the red dashed line can be considered good quality water with low phosphorus (<0.01 mg/L); any sample above the black line is poor quality water with too much phosphorus (>0.1 mg/L). Any sample to the left of the red dashed line is a good water with low nitrogen (<0.5 mg/L); any sample to the right of the black line has too much nitrogen (>1.0 mg/L). Put simply, inside the red dashed line, no nutrient problems; outside the black solid line, problems with either nitrogen or phosphorus or both. And if it lies between the two lines, consider it neither good nor bad, merely “acceptable” (but the location probably needs watching for future changes in direction).”
And here is the full report.