About Phosphorus in the Boise River? Alexandra Etheridge April 6, - - PowerPoint PPT Presentation

What Does USGS Research Tell Us About Phosphorus in the Boise River?

Alexandra Etheridge April 6, 2012

 Boise River history and watershed characteristics  Why Phosphorus?  Spatial Phosphorus Loading 1996-2005  Flow-weighted Phosphorus trends 1994-2010  Boise River & Snake River-Hells Canyon TMDL

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History of the Boise River

 Late 1800s – early 1900s diversions for irrigation, mining  Dams – 1915 Arrowrock, 1950 Anderson Ranch, 1957 Lucky Peak, 1957 Hells Canyon Dam  Geomorphological changes  Water-quality changes, increased nutrients, sediment, bacteria – urban and agriculture  Population in Treasure Valley increased 60% from 1990 to 2010 Boise River ~1900 Boise River Today

Lucky Peak Lake

Photo by ISDA

Why Phosphorus?

• Snake River-Hells Canyon TMDL

– Phosphorus target = 0.07 mg/L – Excess nutrients excess algae hypoxia/death

• Dissolved Phosphorus is a clear driver of Snake

River algae growth

• No clear relationship between nutrients and

floating algae in Boise

• Most algae in Boise River is benthic (attached to

surfaces, bottom)

Total Phosphorous Concentrations (1996-2005)

Target at Mouth 0.07 mg/L Downstream

Smoothed line, Irrigation Season Smoothed line, non-irrigation Season Flow-weighted = Total annual phosphorus load ÷ Total annual Q

Target at Mouth 0.07 mg/L

Flow-weighted Phosphorus at Parma 1994 - 2002

268 326 294 589 298 303 328 302 0.34 0.38 0.40 0.24 0.40 0.32 0.30 0.29

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 100 200 300 400 500 600 700 2003 2004 2005 2006 2007 2008 2009 2010 Flow-weighted annual total phosphorus concentration in milligrams per liter Total Annual Phosphorus Load in tons

Flow-Weighted Total Phosphorus At Parma 2003 - 2010

USGS DATA - PROVISIONAL SUBJECT TO PEER REVIEW

Target at Mouth 97 ton/yr (based on 242 kg/d) Target at Mouth 0.07 mg/L

Robust Data 2008-2010

Study: What does Boise Contribute to Snake?

 Funded by municipalities and USGS  TP at Parma every 49 h  Weekly sampling during Irrigation season in Snake and Boise  Estimated daily loads  15-minute water-quality parameters  Surrogates

What we found:

 Boise River contributes 30% of TP and 72% of OP in Snake  Boise River has higher TP in winter  Boise River more dissolved than particulate  Snake River more particulate than dissolved  Phosphorus drives algae growth in Snake

Snake River Phosphorus & Floating Chlorophyll-a (Algae)

Overall spearman’s rho = -.64

Relative Contribution to Snake

Boise River contributes 11% of mean annual flow in Snake Net uptake of OP in Snake River, Owyhee River contributes ~2 – 4 %

• f nutrient loads measured at Nyssa

30% 53% 17% Total Phosphorus

Boise Snake Other

72% 39%

• 11%

Orthophosphorus 15% 77% 8% Total Nitrogen 13% 50% 37% Suspended Sediment 2% 86% 12% Chlorophyll-a

 All measured TP concentrations in Boise River exceeded the seasonal target of 0.07 mg/L  At Adrian - 13% exceeded target  At Nyssa – 64% exceeded target

Total Phosphorus 2008 - 2010

 Most phosphorus in the Boise river is dissolved  Phosphorus increases downstream  Dissolved phosphorus delivered by the Boise River floating algae growth in the Snake River

Summary

Questions

 3 Synoptic sampling events

 August 2012  October 2012  February 2013

 Up to 40 sites

 25-30 surface water  10-15 groundwater

 Phosphorus mass balance model  USGS Open File Report by June 30, 2013

USGS & IDEQ Synoptic Study

Phosphorus Data Summary 1994 -2005 Explanation

75th percentile

(75% of results are lower than this)

25th percentile

(75% of results are higher than this) Upper Adjacent (Largest result between 75th & 100th percentile)

Median

Lower Adjacent (Lowest result between 25th & 0 percentile)

Outlier Total Number of Samples 55

Total Phosphorus Surrogate Model

Boise River

Seasonal Average TMDL Target

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 10 20 30 40 50 60 70

Dissolved Phosphorous, in mg/L River Mile

Right Bank Center of River Left Bank Surface Water

Parma Eagle Island Diversion Dam Middleton Caldwell Near Mason Slough Glenwood Bridge Notus

GW source of phosphorous to lower Boise River

1 10 100 1000 10000 100 1,100 2,100 3,100 4,100 5,100 6,100 7,100

Daily Mean Flow in cubic feet per second Mean Monthly Total Phosphorus Loads - lbs/day

Estimated Mean Monthly Total Phosphorus Loads in pounds per day Boise River Near Parma, Idaho WY2003 - WY2008

Estimated TP Load 95% Confidence Interval Daily Mean Flow

USGS DATA - PROVISIONAL SUBJECT TO PEER REVIEW

1,000 2,000 3,000 4,000 5,000 6,000 7,000 Mean Monthly Total Phosphorus Loads in pounds per day

Estimated Mean Monthly Total Phosphorus Loads Boise River Near Parma, Idaho WY2003 - WY2008

2003 2004 2005 2006 2007 2008

Most recent biological sampling USGS DATA - PROVISIONAL SUBJECT TO PEER REVIEW

Sediment Concentrations (1996-2005)