A Balancing Act

What Do We Need To Know To Maintain Water QualityIn The

Spokane/Coeur d’Alene Basin?

Mark Solomon, UI-Idaho Water Resources Research InstituteDan Strawn, UI-Environmental Soil Chemistry

UI-IWRRIIdaho Stakeholder

Engagement

IWRRI

Property Owners Coeur

d’Alene Tribe

IDEQ

Water Purveyor

s

Waste Water

Managers

Kootenai County

IDWR

NRCS

UI Faculty

Avista

KEA

Kootenai Aquifer

Protection District

Increased withdrawal Climate change Minimum stream flow Augmented recharge Water quality

Balance: Flow

(Barber, 2011)

Balance: Geochemistry

(Vance, 1995)

• Species are either immobilized or released depending on water and sediment chemistry interaction.

• Aquifer level fluctuation can change that interaction.

• Recharge water chemistry can also change that interaction.

Balance: Nutrients

(WADOE, 2012)

(Coeur d’Alene Tribe, 2012)

Balance: Property Rights

Balance: Property Rights

(IDEQ, 2009)

Coeur d’Alene Lake Management Plan

Balance: Responsibility To Whom?

Where is the Balance Point?

Current Research Objectives

Efficacy and cost of shoreline non-disturbance buffers in reducing nutrient runoff to CdA Lake.

Presence, fate and transport of mineral species and contaminants in the SVRPA.

SVRPA geochemical interaction with different possible recharge sources.

Identifying/quantifying sources of nutrients to CdA Lake.

Zero-sum watershed nutrient cycling.Social, political and economic responses to

management and regulatory change.

CdA shoreline non-disturbance buffers

Need: maintain or reduce nutrient loading to lake from shoreline development as required by Lake Management Plan.

Data gap: shoreline buffer width nutrient removal efficiency not localized for soils and substrate specific to lake.

Multidisciplinary research proposal: Biophysical: Instrument, monitor and analyze representative paired

developed/undeveloped field sites. Social: Survey lakeshore property owners regarding socio-political

beliefs and attitudes that may affect implementation of nutrient control regulation if deemed necessary by responsible authorities.

Economic: Analyze opportunity costs to aggregate property owners of different shoreline buffer widths. Analyze opportunity costs to region if LMP is replaced by CERCLA remedy.

Education: develop and implement live and virtual extension outreach campaign based on project research to improve stakeholder acceptance of necessary effective nutrient management.

Within a watershed P biogeochemical cycling controls fate of P

Erosion/runoff Surface water

Ground waterSoilVadose zoneAquiferMineral P Organic P

Sorbed P

Municipal

Agriculture PlantsNaturalwatershed

Domestic

Inputs

Seepage

mineralization

uptake

precipitation

dissolution

adsorption

desorption

Speciation of P in water Dissolved

Inorganic Orthophosphate Dissolved reactive phosphorus Bioavailable

Organic phosphate compounds Pythic acid (2-50% in plant P), phospholipids, nucleic acids Must be degraded to be bioavailable

Suspended colloids Phosphate attached to small mineral particles

Mobile May pass through filter membrane P needs to desorb or dissolve to become bioavailable

Soil and sediment P P associated with minerals

Operationally defined P categories in surface

waterPhosphorus category

Definition Speciation

Dissolved P (DP)Soluble P (SP)

• Total P <0.45 μm filter or extraction

• P available for plant growth• Dissolved reactive P (DRP),

soluble reactive P (SRP), or molybdate-reactive P (DMRP) are used interchangeably

• Orthophosphate• Colloidal P (<0.45μm)• Easily desorbed P• Dissolved organic P

Particulate P (PP) Suspended P that does not pass through 0.45μm filter

• P adsorbed on mineral and organic particles

• Ca, Al, Fe-P minerals• May convert to DP

Total P (TP) DP+PP All suspended and dissolved P species

Bioavailable P (BAP)

DP + PP determined to biologically available via extraction correlation such using an assay or simulation

• Dissolved orthophosphate

• Readily desorbed or mineralized P

P fluxes from aquatic sediments

Wolford 2008

Important points:Phosphorus available for bio-

uptake is only dissolved orthophosphate.

Concentration of dissolved orthophosphate depends on geochemistry of the system.

Within the watershed, understanding solid phase P is key to predicting P mobility to

surface water.

Types of solid phase P in soils, sediments, vadose

zones (fixed P)Adsorbed

Attachment to the surface of a mineral particle Must desorb to become bioavailable

Precipitated Mineral bound phosphorus

Example: apatite (Ca-P), vivianite (Fe-P), variscite (Al-P)

Must dissolve to become bioavailableDesirable phase for water qualityUndesirable phase for agronomy

Site-specific geochemical factors that affect P

speciationpHSalinityTotal P concentrationCation and anion concentrationTemperatureRedoxMineral surfaces for adsorption

Ground water

Mineral P

Organic PSorbed P mineralization

uptakeprecipitation

dissolution

adsorption

desorption

Example: Minerals have different adsorption

potential

Nidhi Khare Dean Hesterberg, et al.

pH effect on P fixation

http://www.sesl.com.au/fertileminds/200909/Understanding_P_fertilisers.php

3 4 5 6 7 8 9alkaline

fixationby Ca

fixationby Al

Am

ount

of P

fixe

d

pH

fixationby Fe

max Pavailability

low

medium

high

veryhigh

acidic

Redox effects on P cycle Phosphorus exist as P5+ in natural environments, and will not get

reduced However, phosphate strongly associates with Fe oxides

Colloids Soil and sediment Coatings on rocks and sand grains

Iron oxides undergo reductive dissolution when reducing conditions exist

Microbes use Fe as a secondary electron acceptors in low oxygen environments

Dissolution of iron oxides releases sorbed or precipitated phosphate

Patrick et al., 1973

Buffer Width Analysis:Geochemistry Considerations

What is the ability of soil or vadose zone to sequester P?Sequestration is adsorption or precipitationTypically 20% to >90%

Need to know:Soil properties

pH, mineralogy, porosity, particle size, redox potential, organic matter content, microbial activity

Solution propertiesIon constituents, pH, redox potential, temperature,

residence time

Arsenic GeochemistryThroughout the world, there are many

instances of As poisoning occurring from humans drinking groundwater

Sources of arsenic can be natural or anthropogenic

Granitic, carbonaceous, or pyritic minerals may be naturally elevated in As

Management of surface and groundwater environments impacts arsenic solubility

Arsenic in Groundwater

Key points for understanding As

geochemistryArsenic has two common oxidation states

As(III), and As(V) Organic matter and dissolved oxygen cause redox changes

Dissolved arsenic is an oxyanion Arsenate- H2AsO4

-

Arsenite- H3AsO3

There are many forms of organic arsenic Iron oxides are important minerals that adsorb AsPhosphate will competitively exchange on mineral

surfaces with As

Arsenic Geochemistry

Hua Zhang, H.M. Selim

Arsenic in the Coeur d’Aleneand Spokane

ground and surface Waters CDA River, CDA Lake and Spokane River have elevated As in

sediments An oxic cap keeps the As from fluxing into surface water Must maintain redox status (DO) of system to prevent fluxes of As

to surface water Well monitoring of SVRPA indicates elevated As

Predominantly below drinking water standard of 10 ppb Source unknown Need to measure effects of different management on As

geochemistry in SVRPA

SVRPA Hydro-Geochemistry Modeling

The project will develop site-specific knowledge of: Influence of oxidation state on arsenic mobility and the

effect of pumping condition on availability of dissolved arsenic and phosphorus for transport

Sources and sinks for arsenic and phosphorus within the aquifer and on the aquifer boundaries

Factors influencing arsenic and phosphorus transport (e.g., sorption/desorption mechanisms); and cross-correlation and interactions of arsenic, phosphorus, dissolved oxygen, dissolved organic carbon, and other chemicals of concern (e.g., heavy metals).

SVRPA Hydro-Geochemistry Modeling

(cont.)Questions to be addressed

Can specific geological factors be identified that are important for determining the distribution of arsenic, phosphorus, and other species of interest?

What are the necessary water chemistry considerations for augmented aquifer recharge source waters?

Are there optimal locations for siting of potential aquifer recharge projects?

Can knowledge of underlying geology guide water well placement to areas of acceptable water quality?

To what extent are phosphorus levels in aquifer discharge sensitive to changes in aquifer management?

Does water chemistry indicate whether wells within a definable geographic area receive recharge predominantly from one source or another.

SVRPA Hydro-Geochemistry Modeling

(cont.)Project Partners:

Idaho Department of Water ResourcesWashington Department of EcologyKootenai Aquifer Protection DistrictSpokane County Water Resources Idaho Department of Environmental QualityPanhandle Health District

Lakes as Data DepositoriesSediment core

obtained from Lake Coeur d’Alene showing estimated dates of deposition and yellow lines indicating points of sectioning.

(Carter, 2012)

Loading and concentration of phosphorus over the depth of two cores. The dashed line at 11.5 cm indicates the location of the ash layer (1980) and the dashed line at 18 cm indicates the location of the Cs-137 peak (1963) within the cores.

Development Of Hindcasting And Predictive Tools To Assess Nutrient

Control TechnologiesCorrelate historical landscape scale changes in

nutrient control BMP application with their signature in lakebed sediment cores.Model terrestrial and stream processes delivering

P from the Lake Creek, Idaho watershed to the lacustrine environment of Coeur d’Alene Lake.

Assess the ability of a model (WEPP) to simulate long-term changes in sediment and P loading in response to major changes in land use and BMP implementation.

Protecting the balance in the face of climate change: Zero-sum watershed-based nutrient

cyclingClimate change induced shifts in hydrographs

Higher energy rain-on-snow precipitation events as transition zone moves upward Increased energy for pollutant transportAccelerated export of nutrients from the forest to the lacustrine

environment

Reduced availability of nutrients for forest plant communities More susceptible to insects and disease More vulnerable to wildfire Accelerate destabilizing shifts in area river hydrographs

Remobilize bank-deposited contaminants

Protecting the balance in the face of climate change: Zero-sum watershed-

based nutrient cycling (cont.)

Reduced summer baseflow (7Q10)25% reduction already found in Idaho headwater

streams.A 25% reduction in 7Q10 translates to a 66%

reduction in allowable loading for certain parameters such as nutrients, TSS, TDS, and temperature.

It is proposed that Zn currently limits production in CdA LakeRemediation will reduce Zn input

Protecting the Balance: Research Questions

Can forest ecosystems be made more resilient to climate change by reducing the level of exported nutrients from the forest ecosystem? Where, in what form, and in what magnitude do currently exported nutrients

originate in a forest ecosystem? How can forest ecosystem nutrient export be minimized?

What will be the effect of reduced Zn input on lake productivity? Will reduced Zn input change lakebed contaminated sediment mobility? How will climate change affect natural zinc weathering?

In the built environment, can nutrients now exported as waste products from WWTP and on-site disposal be retained and repurposed as a resource? How will dischargers respond to significantly lower permit limits induced by

reduced 7Q10 design minimum flows? Can repurposing of discharge waste as an asset reduce economic, social and

political cost of compliance? Can repurposed nutrients be used to augment resilience of critical watershed

ecosystems?

Zero Net PInput-Output=Storage

watershed