Project Intrepid

May 4, 2013

EXHIBIT (c)(8)

DRAFT

Preliminary and Subject

to Change

Preliminary Materials Prepared for the Conflicts Committee            

of the Board of Directors of Crestwood Gas Services GP LLC

DRAFT

These materials have been prepared by Evercore Group L.L.C. (“Evercore”) for the Conflicts Committee of the Board of Directors (the “Conflicts Committee”)

of Crestwood Gas Services GP LLC (the “Company”), the general partner of Crestwood Midstream Partners LP (the “Partnership”), to whom such materials

are directly addressed and delivered and may not be used or relied upon for any purpose other than as specifically contemplated by a written agreement with

Evercore. These materials are based on information provided by or on behalf of the Partnership and/or other potential transaction participants, from public

sources or otherwise reviewed by Evercore. Evercore assumes no responsibility for independent investigation or verification of such information and has relied on

such information being complete and accurate in all material respects. To the extent such information includes estimates and forecasts of future financial

performance prepared by or reviewed with the management of the Partnership and/or other potential transaction participants or obtained from public sources,

Evercore has assumed that such estimates and forecasts have been reasonably prepared on bases reflecting the best currently available estimates and judgments of

such management (or, with respect to estimates and forecasts obtained from public sources, represent reasonable estimates). No representation or warranty, express

or implied, is made as to the accuracy or completeness of such information and nothing contained herein is, or shall be relied upon as, a representation, whether as

to the past, the present or the future. These materials were designed for use by specific persons familiar with the business and affairs of the Partnership. These

materials are not intended to provide the sole basis for evaluating, and should not be considered a recommendation with respect to, any transaction or other matter.

These materials have been developed by and are proprietary to Evercore and were prepared for the benefit and internal use of the Conflicts Committee.

These materials were compiled on a confidential basis for use by the Conflicts Committee in evaluating the potential transaction described herein and not with a

view to public disclosure or filing thereof under state or federal securities laws, and may not be reproduced, disseminated, quoted or referred to, in whole or in part,

without the prior written consent of Evercore.

These materials do not constitute an offer or solicitation to sell or purchase any securities and are not a commitment by Evercore (or any affiliate) to provide or

arrange any financing for any transaction or to purchase any security in connection therewith. Evercore assumes no obligation to update or otherwise revise these

materials. These materials may not reflect information known to other professionals in other business areas of Evercore and its affiliates.

Evercore and its affiliates do not provide legal, accounting or tax advice. Accordingly, any statements contained herein as to tax matters were neither written nor

intended by Evercore or its affiliates to be used and cannot be used by any taxpayer for the purpose of avoiding tax penalties that may be imposed on such

taxpayer. Each person should seek legal, accounting and tax advice based on his, her or its particular circumstances from independent advisors regarding the

impact of the transactions or matters described herein.

Confidential

DRAFT

Project Intrepid

1

Overview

($ in millions, except per unit amounts)

Market Value Weighted Average Current Yield

As of May 01, 2013

Current

CMLP

NRGM

CMLP

NRGM

Unit Price

$23.53

$25.46

$23.85

$24.55

Current Distribution per Unit

$2.04

$1.58

$2.04

$1.58

Current Yield

8.7%

6.2%

8.6%

6.4%

Market Value

$1,436.9

$2,187.1

$1,456.5

$2,108.9

% of Combined Market Value

39.7%

60.3%

40.9%

59.1%

Market Value Weighted Average Current Yield

7.2%

7.3%

Implied Premium Analysis

As of May 01, 2013

Current

Original

$25.0 MM Payment

$35.0 MM Payment

$40.0 MM Payment

$35.0 MM Payment

CMLP 20-Day VWAP

$24.49

$24.49

$24.49

$24.49

$24.46

5.0% Premium Implied CMLP Price

25.72

25.72

25.72

25.72

25.68

NRGM 20-Day VWAP

23.86

23.86

23.86

23.86

24.00

Implied Exchange Ratio

1.078x

1.078x

1.078x

1.078x

1.070x

Current NRGM Unit Price

$25.46

$25.46

$25.46

$25.46

$24.55

Implied Offer Price

$27.44

$27.44

$27.44

$27.44

$26.27

Plus: Cash Payment

0.41

0.73

1.03

1.17

1.03

Total Price per CMLP Unit

$27.86

$28.18

$28.47

$28.62

$27.30

Current CMLP Unit Price

23.53

23.53

23.53

23.53

23.85

Implied Premium to Current

18.4%

19.8%

21.0%

21.6%

14.4%

Confidential

DRAFT

Overview of Current Proposal

Project Intrepid

2

Pro Forma Ownership Summary

As of May 01, 2013

Current

Exchange

NRGM Units

Exchange

NRGM Units

Unaffiliated Unitholders

1.078x

36.7

1.070x

36.5

Crestwood Holdings

1.078x

21.3

1.070x

20.9

NRGY

1.078x

6.9

1.070x

7.1

Total CMLP LP Units

1.078x

65.0

1.070x

64.5

Pro Forma Unitholders

Units (MM)

% of Total

Units (MM)

% of Total

NRGY

Public

-

NRGY

105.0

56.6%

105.0

56.6%

Crestwood Holdings

53.8

29.0%

53.8

29.0%

Management

26.7

14.4%

26.7

14.4%

Total NRGY Units

185.6

100.0%

185.6

100.0%

NRGM

Public

-

NRGM

17.5

11.6%

17.5

11.6%

Public

-

CMLP

36.7

24.4%

36.5

24.3%

Crestwood Holdings

21.3

14.1%

20.9

13.9%

NRGY Unitholders

56.4

37.4%

56.4

37.5%

NRGY

6.9

4.6%

7.1

4.7%

Management

12.0

8.0%

12.0

8.0%

Total NRGM Units

150.9

100.0%

150.4

100.0%

Confidential

DRAFT

Project Intrepid

3

CMLP Management Financial Projections / NRGM Management Financial Projections (1.070x Exchange Ratio and $35.0 Million Cash Payment )

Standalone Distribution per CMLP Unitholder

$2.07

$2.15

$2.37

$2.60

$2.86

CMLP Current Yield

8.6%

8.6%

8.6%

8.6%

8.6%

CMLP

Standalone

Projected

Unit

Price

-

Current

Yield

(Less

$1.03

per

Unit

Cash

Consideration)

$23.17

$24.12

$26.64

$29.40

$32.45

Pro Forma Distribution per CMLP Unitholder

$1.93

$1.97

$2.18

$2.32

$2.39

NRGM Yield Necessary to Achieve CMLP Standalone Projected Unit Price (Breakeven Yield)

8.3%

8.2%

8.2%

7.9%

7.4%

Incremental GP/IDR Cash Flow Created

($2.1)

$5.2

$16.4

$19.5

$15.9

Total Coverage

1.03x

1.05x

1.04x

1.03x

1.06x

CMLP Management Sensitivity Case / NRGM Management Financial Projections (1.070x Exchange Ratio and $35.0 Million Cash Payment )

For the Years Ending December 31,

2013E

2014E

2015E

2016E

2017E

Standalone Distribution per CMLP Unitholder

$2.04

$2.04

$2.04

$2.04

$2.08

CMLP Current Yield

8.6%

8.6%

8.6%

8.6%

8.6%

CMLP

Standalone

Projected

Unit

Price

-

Current

Yield

(Less

$1.03

per

Unit

Cash

Consideration)

$22.82

$22.82

$22.82

$22.82

$23.27

Pro Forma Distribution per CMLP Unitholder

$1.93

$1.88

$1.97

$2.05

$2.09

NRGM Yield Necessary to Achieve CMLP Standalone Projected Unit Price (Breakeven Yield)

8.4%

8.2%

8.6%

9.0%

9.0%

Incremental GP/IDR Cash Flow Created

($0.6)

($1.5)

$5.9

$13.2

$15.5

Total Coverage

1.03x

1.05x

1.04x

1.03x

1.06x

CMLP Management Financial Projections / NRGM Management Sensitivity Case (1.070x Exchange Ratio and $35.0 Million Cash Payment )

For the Years Ending December 31,

2013E

2014E

2015E

2016E

2017E

Standalone Distribution per CMLP Unitholder

$2.07

$2.15

$2.37

$2.60

$2.86

CMLP Current Yield

8.6%

8.6%

8.6%

8.6%

8.6%

CMLP

Standalone

Projected

Unit

Price

-

Current

Yield

(Less

$1.03

per

Unit

Cash

Consideration)

$23.17

$24.12

$26.64

$29.40

$32.45

Pro Forma Distribution per CMLP Unitholder

$1.93

$1.92

$2.11

$2.28

$2.45

NRGM Yield Necessary to Achieve CMLP Standalone Projected Unit Price (Breakeven Yield)

8.3%

8.0%

7.9%

7.7%

7.5%

Incremental GP/IDR Cash Flow Created

($0.4)

$4.9

$17.3

$28.9

$40.2

Total Coverage

1.00x

1.05x

1.03x

0.96x

0.87x

CMLP Management Sensitivity Case / NRGM Management Sensitivity Case (1.070x Exchange Ratio and $35.0 Million Cash Payment )

For the Years Ending December 31,

2013E

2014E

2015E

2016E

2017E

Standalone Distribution per CMLP Unitholder

$2.04

$2.04

$2.04

$2.04

$2.08

CMLP Current Yield

8.6%

8.6%

8.6%

8.6%

8.6%

CMLP

Standalone

Projected

Unit

Price

-

Current

Yield

(Less

$1.03

per

Unit

Cash

Consideration)

$22.82

$22.82

$22.82

$22.82

$23.27

Pro Forma Distribution per CMLP Unitholder

$1.93

$1.83

$1.90

$1.99

$2.07

NRGM Yield Necessary to Achieve CMLP Standalone Projected Unit Price (Breakeven Yield)

8.4%

8.0%

8.3%

8.7%

8.9%

Incremental GP/IDR Cash Flow Created

$1.2

($0.8)

$6.6

$20.2

$30.5

Total Coverage

1.00x

1.05x

1.03x

0.96x

0.87x

For the Years Ending December 31,

2013E

2014E

2015E

2016E

2017E

Current Proposal from Crestwood Holdings of $35.0 Million Cash ($1.03 per Unit)

($ in millions, except per unit amounts)

Confidential

DRAFT

Original Committee Request of $40.0 Million Cash ($1.17 per Unit) as of May 1, 2013

Project Intrepid

4

CMLP Management Financial Projections / NRGM Management Financial Projections (1.078x Exchange Ratio and $40.0 Million Cash Payment )

For the Years Ending December 31,

2013E

2014E

2015E

2016E

2017E

Standalone Distribution per CMLP Unitholder

$2.07

$2.15

$2.37

$2.60

$2.86

CMLP Current Yield

8.7%

8.7%

8.7%

8.7%

8.7%

CMLP

Standalone

Projected

Unit

Price

-

Current

Yield

(Less

$1.17

per

Unit

Cash

Consideration)

$22.70

$23.64

$26.12

$28.85

$31.85

Pro Forma Distribution per CMLP Unitholder

$1.93

$1.98

$2.19

$2.33

$2.41

NRGM Yield Necessary to Achieve CMLP Standalone Projected Unit Price (Breakeven Yield)

8.5%

8.4%

8.4%

8.1%

7.6%

Incremental GP/IDR Cash Flow Created

($2.3)

$4.9

$16.2

$19.4

$15.8

Total Coverage

1.03x

1.05x

1.04x

1.03x

1.06x

CMLP Management Sensitivity Case / NRGM Management Financial Projections (1.078x Exchange Ratio and $40.0 Million Cash Payment )

For the Years Ending December 31,

2013E

2014E

2015E

2016E

2017E

Standalone Distribution per CMLP Unitholder

$2.04

$2.04

$2.04

$2.04

$2.08

CMLP Current Yield

8.7%

8.7%

8.7%

8.7%

8.7%

CMLP

Standalone

Projected

Unit

Price

-

Current

Yield

(Less

$1.17

per

Unit

Cash

Consideration)

$22.36

$22.36

$22.36

$22.36

$22.79

Pro Forma Distribution per CMLP Unitholder

$1.93

$1.89

$1.98

$2.06

$2.10

NRGM Yield Necessary to Achieve CMLP Standalone Projected Unit Price (Breakeven Yield)

8.6%

8.5%

8.9%

9.2%

9.2%

Incremental GP/IDR Cash Flow Created

($0.7)

($1.7)

$5.6

$13.1

$15.4

Total Coverage

1.03x

1.05x

1.04x

1.03x

1.06x

CMLP Management Financial Projections / NRGM Management Sensitivity Case (1.078x Exchange Ratio and $40.0 Million Cash Payment )

For the Years Ending December 31,

2013E

2014E

2015E

2016E

2017E

Standalone Distribution per CMLP Unitholder

$2.07

$2.15

$2.37

$2.60

$2.86

CMLP Current Yield

8.7%

8.7%

8.7%

8.7%

8.7%

CMLP

Standalone

Projected

Unit

Price

-

Current

Yield

(Less

$1.17

per

Unit

Cash

Consideration)

$22.70

$23.64

$26.12

$28.85

$31.85

Pro Forma Distribution per CMLP Unitholder

$1.93

$1.93

$2.12

$2.29

$2.46

NRGM Yield Necessary to Achieve CMLP Standalone Projected Unit Price (Breakeven Yield)

8.5%

8.2%

8.1%

7.9%

7.7%

Incremental GP/IDR Cash Flow Created

($0.6)

$4.6

$17.0

$28.6

$39.9

Total Coverage

1.00x

1.05x

1.03x

0.96x

0.87x

CMLP Management Sensitivity Case / NRGM Management Sensitivity Case (1.078x Exchange Ratio and $40.0 Million Cash Payment )

For the Years Ending December 31,

2013E

2014E

2015E

2016E

2017E

Standalone Distribution per CMLP Unitholder

$2.04

$2.04

$2.04

$2.04

$2.08

CMLP Current Yield

8.7%

8.7%

8.7%

8.7%

8.7%

CMLP

Standalone

Projected

Unit

Price

-

Current

Yield

(Less

$1.17

per

Unit

Cash

Consideration)

$22.36

$22.36

$22.36

$22.36

$22.79

Pro Forma Distribution per CMLP Unitholder

$1.93

$1.85

$1.91

$2.00

$2.08

NRGM Yield Necessary to Achieve CMLP Standalone Projected Unit Price (Breakeven Yield)

8.6%

8.3%

8.5%

8.9%

9.1%

Incremental GP/IDR Cash Flow Created

$1.0

($1.1)

$6.4

$19.9

$30.3

Total Coverage

1.00x

1.05x

1.03x

0.96x

0.87x

($ in millions, except per unit amounts)

Confidential

DRAFT

Crestwood Holdings Offer of $25.0 Million Cash ($0.73 per Unit) as of May 1, 2013

Project Intrepid

5

CMLP Management Financial Projections / NRGM Management Financial Projections (1.078x Exchange Ratio and $25.0 Million Cash Payment )

For the Years Ending December 31,

2013E

2014E

2015E

2016E

2017E

Standalone Distribution per CMLP Unitholder

$2.07

$2.15

$2.37

$2.60

$2.86

CMLP Current Yield

8.7%

8.7%

8.7%

8.7%

8.7%

CMLP

Standalone

Projected

Unit

Price

-

Current

Yield

(Less

$0.73

per

Unit

Cash

Consideration)

$23.14

$24.08

$26.56

$29.29

$32.29

Pro Forma Distribution per CMLP Unitholder

$1.93

$1.98

$2.19

$2.33

$2.41

NRGM Yield Necessary to Achieve CMLP Standalone Projected Unit Price (Breakeven Yield)

8.3%

8.2%

8.2%

8.0%

7.5%

Incremental GP/IDR Cash Flow Created

($2.3)

$4.9

$16.2

$19.4

$15.8

Total Coverage

1.03x

1.05x

1.04x

1.03x

1.06x

CMLP Management Sensitivity Case / NRGM Management Financial Projections (1.078x Exchange Ratio and $25.0 Million Cash Payment )

For the Years Ending December 31,

2013E

2014E

2015E

2016E

2017E

Standalone Distribution per CMLP Unitholder

$2.04

$2.04

$2.04

$2.04

$2.08

CMLP Current Yield

8.7%

8.7%

8.7%

8.7%

8.7%

CMLP

Standalone

Projected

Unit

Price

-

Current

Yield

(Less

$0.73

per

Unit

Cash

Consideration)

$22.80

$22.80

$22.80

$22.80

$23.24

Pro Forma Distribution per CMLP Unitholder

$1.93

$1.89

$1.98

$2.06

$2.10

NRGM Yield Necessary to Achieve CMLP Standalone Projected Unit Price (Breakeven Yield)

8.5%

8.3%

8.7%

9.0%

9.0%

Incremental GP/IDR Cash Flow Created

($0.7)

($1.7)

$5.7

$13.1

$15.4

Total Coverage

1.03x

1.05x

1.04x

1.03x

1.06x

CMLP Management Financial Projections / NRGM Management Sensitivity Case (1.078x Exchange Ratio and $25.0 Million Cash Payment )

For the Years Ending December 31,

2013E

2014E

2015E

2016E

2017E

Standalone Distribution per CMLP Unitholder

$2.07

$2.15

$2.37

$2.60

$2.86

CMLP Current Yield

8.7%

8.7%

8.7%

8.7%

8.7%

CMLP

Standalone

Projected

Unit

Price

-

Current

Yield

(Less

$0.73

per

Unit

Cash

Consideration)

$23.14

$24.08

$26.56

$29.29

$32.29

Pro Forma Distribution per CMLP Unitholder

$1.93

$1.93

$2.12

$2.29

$2.46

NRGM Yield Necessary to Achieve CMLP Standalone Projected Unit Price (Breakeven Yield)

8.3%

8.0%

8.0%

7.8%

7.6%

Incremental GP/IDR Cash Flow Created

($0.6)

$4.6

$17.0

$28.6

$39.9

Total Coverage

1.00x

1.05x

1.03x

0.96x

0.87x

CMLP Management Sensitivity Case / NRGM Management Sensitivity Case (1.078x Exchange Ratio and $25.0 Million Cash Payment )

For the Years Ending December 31,

2013E

2014E

2015E

2016E

2017E

Standalone Distribution per CMLP Unitholder

$2.04

$2.04

$2.04

$2.04

$2.08

CMLP Current Yield

8.7%

8.7%

8.7%

8.7%

8.7%

CMLP

Standalone

Projected

Unit

Price

-

Current

Yield

(Less

$0.73

per

Unit

Cash

Consideration)

$22.80

$22.80

$22.80

$22.80

$23.24

Pro Forma Distribution per CMLP Unitholder

$1.93

$1.85

$1.91

$2.00

$2.08

NRGM Yield Necessary to Achieve CMLP Standalone Projected Unit Price (Breakeven Yield)

8.5%

8.1%

8.4%

8.8%

9.0%

Incremental GP/IDR Cash Flow Created

$1.0

($1.1)

$6.4

$19.9

$30.3

Total Coverage

1.00x

1.05x

1.03x

0.96x

0.87x

($ in millions, except per unit amounts)