the state of our groundwater

Taylor County and Beyond: The State of

Our Groundwater

Steve Oberle Taylor County Conservationist

Outline

• Groundwater basics• Watersheds and wellhead recharge/protection• Basic approaches to groundwater issues• Taylor County drinking water education/testing• General factors influencing site-specific

groundwater quality/quantity• Wisconsin aquifers• Well records (logs) and water test results• Top 10 list of lesser-known groundwater facts

Groundwater and the Earth’s Fresh Water Supply

Groundwater and the Water Cycle

Taylor County water budget/cycle (values vary with location)

Mean precipitation 31 inches/yearMean runoff 8 to 10 inches/yearEvaporation/transpiration 18 to 20 inches/yearBecomes groundwater 1 - 5 inches /year

Wisconsin Watersheds

watershed is to a water body

as

well recharge area is to a well

watershed – an area of land that drains to a common water body (eg. Yellow River)

well recharge area – an area of land where precipitation infiltrates the land/soil and recharges an aquifer that provides water for a particular well or group of wells

Wellhead Recharge Areas

Medford municipal wellhead recharge areas

Source Water (Wellhead) Protection

Source Water (Wellhead) Protection: Definition of Terms

Cone of Depression: – a “cone-shaped” depression in the water table around a well caused by the withdrawal of water from pumping. Source Water (Wellhead) Protection: Voluntary action taken to prevent the pollution of drinking water sources, including groundwater, lakes, rivers, and streams. Source water protection is developing and implementing a plan to manage land uses and potential contaminants. To be effective, source water protection should be directed to major threats to the drinking water source identified in the source water assessment. As part of the source water protection plan, a contingency plan for use in the event of an emergency is developed. Source water protection for groundwater is also called wellhead protection.Wellhead: the wellhead is a well or group of wells that provides the source of public drinking water along with the structures built on top of and around the wells.Wellhead Protection Area: a designated surface and subsurface area surrounding a well or well field that supplies a public water supply and through which contaminants or pollutants are likely to pass and eventually reach the aquifer that supplies the well or well field. The purpose of designating the area is to provide protection from the potential of contamination of the water supply. These areas are designated in accordance with laws, regulations, and plans that protect public drinking water supplies. Wellhead Recharge Area: an area of land where precipitation infiltrates the land/soil and recharges an aquifer that provides water for a particular well or group of wells.Zone of Influence: the area encompassed within a calculated radius of a well, representing the area of a cone of depression, defined by a drawdown of one foot, that would develop after 30 days of pumping (at full capacity).

Two basic approaches to groundwater quality/quantity issues

Bottom up

Top down

Approaches to Groundwater Quality/Quantity Issues

Bottom up • based initially on the groundwater resource and its quality and quantity

at whatever scale is being investigated

• relevant information • groundwater monitoring data• drinking water quality testing data • groundwater quantity data/information • applicable groundwater & drinking water quality/quantity regulations &

standards

• represents the sum total of our knowledge/understanding of the quality and quantity of local, regional, state-wide, or national groundwater resources

• as an example, Taylor County has primarily focused on a bottom up

approach to groundwater programming since about 1985

2011 Taylor County Drinking Water Education/Testing Program

Bottle Distribution Dates/ Times: May 31 – J une 3 (Tuesday thru Friday, 8:30 a.m.- 4:30 p.m.) Location: Taylor County Land Conservation Department

925 Donald St. Room 104, Medford

Date: J une 1, Wednesday Location/ Time: Westboro VFW Hall (1:00 - 4:00 p.m.)

Date: J une 2, Thursday Locations/ Times: Gilman Market (9:00 a.m. – noon) Skabroud’s Store, J ump River (1:00 – 4:00 p.m.)

Water Testing Date and Sample Return Date/ Times: J une 6, Monday (8:30 a.m.- 4:30 p.m.) Location: Taylor County Land Conservation Department 925 Donald St. Room 104, Medford

Date: J une 6, Monday Locations/ Times: Gilman Market (8:00 a.m.– 10:00 a.m.) Skabroud’s Store, J ump River (11:00 a.m.- 1:00 p.m.) Westboro VFW Hall (2:00 p.m.– 4:00 p.m.)

--------------------------------------------

Contact the Taylor County Land Conservation

Department at 748-1469 for more

information.

Private Wells Sampled (1985-2012)

“Homeowner” Water Tests (1985-2012)

“Metals” Water Tests (1985-2012)

Nitrate in Taylor County Groundwater (1985-2012)SDWS = 10 mg/l

Chloride in Taylor County Groundwater (1985-2012)

Phosphorus in Taylor County Groundwater (2001-2012)

Iron in Taylor County Groundwater (1998-2012)

Manganese in Taylor County Groundwater (1998-2012)HAL = 0.3 mg/l

Arsenic in Taylor County Groundwater (2000-2012)SDWS = 10 ug/l

Drinking water quality health effects

Element Health effect(s)

Arsenic skin, bladder, lung, liver, colon, and kidney cancers; blood vessel damage; high blood pressure; nerve damage; anemia; stomach upsets; diabetes; skin changes; learning disabilities

Iron diabetes, heart disease

Manganese nervous system/neurological effects, Parkinson’s type disorder; irritability

Nitrate methemoglobinemia (blue baby syndrome); central nervous system depression (headaches, dizziness, fatigue, lethargy); coma; convulsions; abnormal heart rhythms; circulation failure; hemolytic anemia; goiter; respiratory infections;

bladder/ovarian cancers; miscarriages.

Sodium high blood pressure

Taylor County SummaryThe Taylor County drinking water education and testing program is one potential “bottom up” approach to groundwater programming in Wisconsin.

Drinking water quality testing has revealed several potential human and environmental health hazards in Taylor County groundwater (eg. As, Cl, Fe, Mn, Na, P).

Taylor County has found two key components to conducting a successful groundwater/drinking water education and testing program (ie. accessibility, cost).

Further research on groundwater issues in Taylor County, the surrounding region, and WI has revealed several key factors to consider in interpreting groundwater quality and quantity data, and in predicting potential endpoints or effects from changes in land cover, management, use, and/or natural factors (eg. precipitation/recharge).

Approaches to Groundwater Quality/Quantity Issues

Top (surface) down

*based on the premise or perspective that whatever groundwater and drinking water quality and quantity issues exist at a given scale; there also ultimately exists a finite set of factors (human and natural) that play a role, or are responsible.

*knowing these factors and their relative effects/impacts is key to understanding the causes/effects of groundwater quality and quantity issues, and to predicting the effects of changes in human (eg. land management/use) and natural (eg. precipitation) influences on the groundwater resource.

Top Down (General Factors)

* the local and regional ages, extent, and phases of glaciation (and the resulting natural landforms and topography)

* the local and regional hydrology and water budget (eg. precipitation and recharge potential)

* the historic and current land cover/management/use (eg. W ditches)

* the well drilling location and sanitation (eg. Fe bacteria)

* local and regional groundwater pumping, drawdown, and withdrawal (from the watershed)

* the local and regional soil types (series) present at the surface as well as any buried paleosols within the underlying glacial material

* the characteristics/depths/types of unconsolidated (glacial) material/till

* the depth to and type of bedrock material

* the aquifer type(s)

Top (surface) down factors influencing groundwater quality/quantity: Ages and phases of glaciation

Top (surface) down factors influencing groundwater quality/quantity: Local-regional hydrology/water budget (eg. precipitation and recharge

potential)

Top (surface) down factors influencing groundwater quality/quantity: Local and regional hydrology and water budget

Hydrogeology and Stream ecology notesCase example: Little Black Township, Taylor County WI

Streams in all drainage basins follow certain rules. They all are connected by a one-way network by which small tributaries drain into larger ones with a definite pattern. The number of streams and their distance apart both follow and a fairly orderly distribution.

Most tributaries of about the same size are about the same length, and the intervals between the mouths of tributaries are fairly uniform. The larger the drainage area, the longer the stream, the ratio between the two being constant for similar terrains.

Though all drainage networks branch in the same way, the shape of their patterns varies greatly from one kind of terrain to another, mainly a response to the rock type or structural pattern of folds and faults. The most common is dendritic drainage, named for the characteristic pattern shown by most branching deciduous trees. This fairly random pattern is typical of terrain floored by uniform rock types, such as horizontal sedimentary rocks or massive igneous or metamorphic rocks.

Differential weathering of fractures or joint systems in bedrock localizes stream flow, producing a more ordered and geometrical rectangular drainage pattern. Thus, drainage patterns reflect mainly the underlying structure of the rocks and their varying resistance to erosion, though the density of drainage depends more on climate.

Top (surface) down factors influencing groundwater quality/quantity: Local and regional hydrology and stream ecology

Typical dendritic drainage pattern

Typical rectangular drainage pattern developed on a strongly jointed rocky terrain. Drainage tends to follow the joint pattern. Differential weathering of fractures or joint systems in bedrock localizes stream flow.

A few words about local/regional hydrology and water budgets

Context: hydrologic systems (cycle)Observations: natural systems are by nature circular (eg. hydrologic, geologic, N, P, S cycles); human systems are for the most part linear.At issue with the hydrologic cycle:*short-circuits (eg. W ditches)*accelerations (eg. liquid manure and karst)

Example: short-circuit of water cycle – in this case leading to much less groundwater recharge potential

Top (surface) down factors influencing groundwater quality/quantity: Land cover/management/use

Frequency of occurrence of natural vegetation including wetlands, riparian areas, forests, and rangeland.

Frequency of land used for crops and pasture. Note: “corn belt” region of upper Midwest

Frequency of land with artificial drainage.

Frequency of land where irrigation supplies more than half of crop water requirements.

Midwestern groundwater quality issues

The intense application of nitrogen-fertilizer to cropland in the midwestern United States has created concern about nitrate contamination of the region's aquifers. Since 1991, the US Geological Survey has used a network of 303 wells to investigate the regional distribution of nitrate in near surface aquifers of the midwestern United States. Detailed land use and soil data were compiled within a 2 km radius of 100 unconsolidated wells in the regional network to determine relations to nitrate concentrations in groundwater. For land use, the amount of irrigated land was directly related to nitrate concentrations in groundwater. For soils, the general water table depth and soil factors associated with rates of water movement were directly related to nitrate concentrations in groundwater.

Kolpin et al., 1995

Top (surface) down factors influencing groundwater quality/quantity: Well drilling/location/sanitation

Top (surface) down factors influencing groundwater quality/quantity: Groundwater pumping, drawdown, and withdrawal (from watershed)

Top (surface) down factors influencing groundwater quality/quantity: Soil series (type)

Top (surface) down factors influencing groundwater quality/quantity: Thickness and composition of glacial till and

unconsolidated material

Top (surface) down factors influencing groundwater quality/quantity:

Thickness and composition of glacial till and pleistocene geology

Top (surface) down factors influencing groundwater quality/quantity: Thickness and composition of glacial till and pleistocene geology

Top (surface) down factors influencing groundwater quality/quantity: Depth to bedrock and bedrock geology

Top (surface) down factors influencing groundwater quality/quantity:

Aquifer type

Sand and gravel aquifer Silurian dolomite aquifer

Sandstone aquiferCrystalline bedrock aquifer

Wisconsin’s AquifersSand and gravel

* surficial material (rock debris/glacial drift) covering most of the state except for parts of the southwest

* mostly sand and gravel deposited from glacial ice or in river floodplains

* loose deposits, often referred to as soil, but much more than just a few feet of topsoil (these deposits are > 300 feet thick in some places)

* as the ice melted, large amounts of sand and gravel were deposited, forming “outwash plains”

* pits formed in the outwash where buried blocks of ice melted; many of these pits are now lakes

* the sand and gravel outwash plains now form some of the best aquifers in Wisconsin

* many of the irrigated agricultural lands in central, southern and northwestern Wisconsin use the glacial outwash aquifer

* other glacial deposits are also useful aquifers, but in some places, large glacial lakes accumulated thick deposits of clay. These old lake beds of clay do not yield or transmit much water

* because the top of the sand and gravel aquifer is also the land surface for most of Wisconsin, it is highly susceptible to human-induced and naturally occurring pollutants

Wisconsin’s AquifersEastern (Silurian) dolomite

• occurs only in eastern Wisconsin from Door County to the WI-IL border

• consists of Niagara dolomite underlain by Maquoketa shale

• holds groundwater in interconnected cracks and pores

• water yields mostly dependent on the number of fractures the well intercepts (not unusual for nearby wells to vary greatly in terms of actual well yields)

• shallow portions can easily become contaminated in places where the fractured dolomite bedrock occurs at or near the land surface. In these areas (such as parts of Door, Kewaunee and Manitowoc counties) little soil to filter pollutants carried or leached by precipitation. Little or no filtration takes place once the water reaches large fractures in the dolomite, and this has resulted in some groundwater quality problems, such as bacterial contamination from human and animal wastes

• special care is necessary to prevent pollution

Wisconsin’s Aquifers

Sandstone and dolomite

• consists of layers of sandstone and dolomite bedrock that vary greatly in their water-yielding properties. (In dolomite, groundwater mainly occurs in fractures; in sandstone, groundwater occurs in pore spaces between loosely cemented sand grains

• these formations can be found over the entire state, except in the

north central portion

• lies below the eastern dolomite aquifer and the Maquoketa shale layer in eastern WI. Lies beneath the sand and gravel aquifer in other areas

• the principal bedrock aquifer for the southern and western portions of WI

• In eastern Wisconsin, most users of substantial quantities of

groundwater, such as cities and industries, tap this deep aquifer to obtain a sufficient amount of water

A few words about karst

There’s an experiment being played out in the karst areas of WI right now – even as we speak. An experiment involving the interaction between liquid wastes (of any kind) and the landscapes (karst areas) they are being applied to. An experiment to determine if accelerating the natural systems and processes that created this type of environment (ecosystem) in the first place, (ie. the interactions between water and rock) will ultimately (and horribly) result in acute and/or chronic contamination of groundwater and drinking water supplies within the karst regions.

A few words about karst

Context: hydrologic systems (cycle)Observations: natural systems are by nature circular (eg. hydrologic, geologic, N, P, S cycles); human systems are for the most part linear.At issue with the hydrologic cycle:*short-circuits (eg. W ditches)*accelerations (eg. liquid manure and karst)

What is Karst?• A type of topography that is formed on

limestone, gypsum, and other rocks, primarily by dissolution, and is characterized by sinkholes, caves, and underground drainage (Glossary of Geology)

• Spectrum of landscapes -- Door Co. to tower karst of China

• Significant land area - 20% of U.S., 40% of area east of Mississippi River

Flow Characteristics of Karst Aquifers• Dense and ubiquitous fracture network

– little surface runoff– water easily infiltrates to subsurface

• Recharge – exceedingly rapid – carries surface contaminants to the water table

• Flow within the aquifer occurs primarily along bedding plane fractures– Little to no attenuation of contaminants within the aquifer

• Flow rates vary from 10’s to 100’s of ft/day

“Karst Potential” in Wisconsin

Soil Depth

Cracks in carbonate bedrock where water and nutrients can flow into groundwater

Bedrock Fracture Expressions

Karst features:

Example: acceleration of hydrologic cycle (processes)

(karst and liquid manure)

Sinkhole formation

Sinkholes

Dancing Waters Development Pond, Woodbury, Minnesota

12 October 2005

Slide compliments of E. Calvin Alexander, Jr.

Slide compliments of E. Calvin Alexander, Jr.

Summary NE Wisconsin• Hydrogeology of the Silurian aquifer is well understood

– Water infiltrates rapidly with little attenuation of contaminants

• There are water-quality problems in the karst areas of NE Wisconsin

– Several documented “brown water” episodes– ~30 to 50 % of wells do not meet drinking water standards

• Geologic setting makes this area especially vulnerable to groundwater contamination

Summary for SW Wisconsin• Karst Hydrogeology

– Geologic units are not the same as NE WI– Groundwater flow systems differ from NE WI– Are hydrologic studies for Sauk & Iowa Counties– More research needed on basic hydrogeology

• Water Quality Results– Limited WQ results for several counties– Existing data suggest:

• elevated nitrate values • % of wells with bacteria (~28%) is slightly above state average

(~21%)

Wisconsin’s AquifersCrystalline bedrock

• underlies the entire state and is the only bedrock aquifer in the northern quarter of the state

• is composed of various rock types (aka “basement rocks”) formed during the Precambrian Era

• cracks and fractures storing and transmitting water in these dense rocks are not spaced uniformly; some areas contain numerous fractures while others contain very few

• to obtain water, a well must intersect some of these cracks; the

amount of water available to a well can vary within a single home site

• this aquifer cannot provide adequate quantities of water for larger municipalities, large dairy herds, or industries (many wells in the crystalline bedrock aquifer have provided good water; most of these wells do not penetrate deeply into the rock)

Factors influencing groundwater quality/quantity: Local/regional aquifer type

Groundwater Availability – SE Taylor County

Baseflow: streamflow coming from groundwater seepage into a stream or river. Baseflow is the continual contribution of groundwater to rivers and is an important source of flow between rainstorms.

Groundwater quality/quantity:Well records (logs) and water test results

* well records (logs) * drinking water testing data

Potentially the two most critical documents or sources of information in groundwater programming at the local (site-specific), regional, and state-wide levels.

Jump River, WI

On the horizon……*on-going compilation/integration and dissemination of local, regional, and state-wide groundwater/drinking water information

*on-going local, regional, and state-wide well summarization and mapping

*local-regional strategic planning/ordinance-policy development (eg. Stetsonville-Little Black, karst)

*water supply protection (WSP)*source water (wellhead) protection (WHP)

*WLWCA Groundwater Information Network (proposed)

*WI Groundwater Data Viewer (proposed)