The Water Withdrawal Assessment Process Context within regional water policy discussions Context within regional water policy discussions –Aquatic ecosystems now a priority “user” –No “Adverse Resource Impact” –Ground- & Surface-water connections recognized Groundwater Conservation Advisory Council Groundwater Conservation Advisory Council –Convened by the legislature –Broadly representative of societal water use interests –Charged with definitions, design of science-based process and screening tool, and guidance on policy –National science review panel

The Flow Regime Paradigm -- There is a geography of flow regimes -- Fish species are adapted to habitats controlled by certain quantities of, and variability in, river flows Climate GeologyLanduse Flow regime HydraulicsChannelNutrientsTemperature

Michigan rivers naturally have different flow regimes, and thus different habitat conditions, biological communities, sensitivity to disturbance, and potential for fishery management.

Michigan Streams by Flow

Midwest Streams by Flow

Index Flow Stressful, low flow period

The Water Withdrawal Assessment Process Groundwater Stream Flow Fish Populations  Three Models Interact within the impact assessment model Withdrawal Model - How much water is in the aquifer, is being withdrawn, and from where and how it will affect stream flow Streamflow Model - How much water is flowing in the stream during summer low flow periods Fish Impact Model - What fish are in the stream and what is the likely effect of removing water on those groups of fish FeedsSupports

The Water Withdrawal Assessment Process This is the process that the user goes though to see whether the proposed withdrawal is OK or is likely to cause an adverse effect on fish populations This is the process that the user goes though to see whether the proposed withdrawal is OK or is likely to cause an adverse effect on fish populations Screening Tool – The Automated Analysis within the model based on general, state-wide data for a given withdrawal Screening Tool – The Automated Analysis within the model based on general, state-wide data for a given withdrawal Site Specific Analysis – Same process but using professional evaluation of site-specific data on flow, geology or fish Site Specific Analysis – Same process but using professional evaluation of site-specific data on flow, geology or fish

1. The Withdrawal Model Model needs to know how much water is in the local aquifer Automatically determines where the nearest streams are. –Apportions the withdrawal effect between streams Calculates the likely reduction in flow due to the proposed withdrawal Rain and Snow – Recharge to area

Characteristics of the Withdrawal Model Distance Matters Distance Matters – A well adjacent to a river will very quickly get water either from water that would have gone to the river or directly from the river – A well farther from a river will get more water from storage and require a longer time to affect the stream Geology and Soil Matters Geology and Soil Matters – Clay soils are “tight” and water does not move easily – Sandy soils are “porous” and water flows quickly

2. The Streamflow Model  Need to Know How Much Flow is in any Stream Segment  “Index flow”; low flow period in the year  Look at the segments where we know the flow (132 stream gauges in the State) and extrapolate these to the streams that are not gauged Major Factors Used  Drainage Basin Size  Forest Cover  Geology and Soils  Precipitation

Index Flow Stressful, low flow period

Major Factors in the Analysis  The geographic database contains info for 11,000 distinct watersheds and streams  Info on watershed location, size, geology; and on stream flow, temperature, and fish populations  Resulting maps closely match field experiences

3. The Fish Response Model  What fish populations live where in the streams and how do they respond to flow reductions in the summer (at low flow)

Smallmouth bass Fish habitat optima identified - Low-flow yield, catchment area, and July mean temperature - 82 most common species

Each fish species has a habitat optimum and suitability curve. Abundance Habitat Gradient (Flow or Temperature for instance) For ~ 60 fish species we determined these for 1) Catchment area, 2) summer base-flow yield, and 3) July mean temperature. We assigned scores of 4, 3, 2, 1, 0 (respectively) to each 0.5 standard deviation increment away from the optimum for that habitat variable. Optimum Habitat ‘4’ represents ‘best’ conditions ‘4’ is ± 0.5 SD ‘3’ is ± 0.5 to 1.0 SD ‘2’ is ± 1.0 to 1.5 SD ‘1’ is ± 1.5 to 2.0 SD ‘0’ is ± > 2.0 SD

Below state median Above state median 2X state median Thriving Characteristic Abundance

Streams Cold Cool Warm Lg RiversSm Rivers Cold Trans We grouped Michigan streams into types and developed response models using an average of ~ 20 specific segments per type 20 Cold Sm Rivers 20 Warm Streams X

All River Segment Types

What Can the Fish Curves Tell Us About Functional Impairment?

Baseline or existing condition Some replacement of sensitive species Some density changes in fish Notable replacement by tolerant species Tolerant species dominant; ecological functions altered Severe alteration of ecological structure and function Interpretive criteria from Davies and Jackson 2006 What Can the Fish Curves Tell Us About Functional Impairment?

ABCD Adverse Resource Impact Gradient of increasing risk Interpreting the Fish Curves Characteristic Fish Thriving Fish 90% 80%

Cold Streams