Mill Creek Master Plan
Technical Appendix - Volume 2

Section 1

1.01 Mill Creek Flood Control Project
1.02 Project Authorization
1.03 Project Purpose
1.04 Project Benefits
1.05 Project Management
1.06 References

2.01 General
2.02 Ecological Factors
2.03 Cultural Factors
2.04 References

3.01 General
3.02 Ecological Factors
3.03 Project Cultural Factors
3.04 Aesthetic Resources
3.05 References

4.01 General
4.02 Land Classifications
4.03 Tradeoff Analysis
4.04 References

Item 1 Prior Reports on Mill Creek Project

Item 2 Public Laws, Executive Orders, and Regulations Pertinent to the Mill Creek Project

Item 3 Pertinent Data

Item 4 Geographic Information Systems

Item 5 List of Aerial Photography

Item 6 Climate Data

Item 7 Vegetation Inventory at the Mill Creek Project - Trees, Shrubs, Forbs, and Grasses

Item 8 Songbird Inventory

Item 9 Fish Inventory

Item 10 Mill Creek Project Real Estate Map

Item 11 Carrying Capacity Methodology

Item 12 Mill Creek Soil Capability Classes

Plate 2-0	Mill Creek Regional Base Map (595K)
Plate 2-1	Mill Creek Regional Physiography (675K)
Plate 2-2	Reserved
Plate 2-3	Reserved
Plate 2-4	Mill Creek Regional Hydrology (582K)
Plate 2-5	Mill Creek Regional Precipitation (798K)
Plate 2-6	Mill Creek Regional Vegetation (750K)
Plate 2-7	Reserved
Plate 2-8	Reserved
Plate 2-9	Reserved
Plate 2-10	Reserved
Plate 2-11	Reserved
Plate 2-12	Reserved
Plate 2-13	Reserved
Plate 2-14	Mill Creek Regional Birds (513K)
Plate 2-15	Mill Creek Regional Raptors (605K)
Plate 2-16	Mill Creek Regional Raptors (671K)
Plate 2-17	Mill Creek Regional Waterfowl (626K)
Plate 2-18	Mill Creek Regional Waterfowl (743K)
Plate 2-19	Mill Creek Regional Upland Game (665K)
Plate 2-20	Mill Creek Regional Upland Game (641K)
Plate 2-21	Mill Creek Regional Mammals (706K)
Plate 2-22	Mill Creek Regional Big Game (707K)
Plate 2-23	Mill Creek Regional Big Game (683K)
Plate 2-24	Mill Creek Regional Big Game (608K)
Plate 2-25	Mill Creek Regional Market Area (555K)
Plate 2-26	Mill Creek Regional Access and Population (640K)
Plate 2-27	Mill Creek Regional Land Use and Cover (743K)
Plate 2-28	Mill Creek Regional Ownership (748K)
Plate 2-29	Mill Creek Regional Recreation (613K)
Plate 3-0	Mill Creek Project Base Map (658K)
Plate 3-1	Mill Creek Topography (788K)
Plate 3-2	Mill Creek Slope (827K)
Plate 3-3	Mill Creek Aspect (795K)
Plate 3-4	Mill Creek Geology (782K)
Plate 3-5	Mill Creek Soils (907K)
Plate 3-6	Land Cover/Vegetation (877K)
Plate 3-7	Reserved
Plate 3-8	1861 Survey (412K)
Plate 3-9	Project Monumentation (452K)
Plate 3-10	Land Ownership (746K)
Plate 3-11	Outgrants and Easements (349K)
Plate 3-12	Land Allocation and Disposals (747K)
Plate 3-13	City and County Land Use Plan (702K)
Plate 3-14	Operational Facilities (557K)
Plate 3-15	Lake Elevations (814K)
Plate 3-16	Fish and Wildlife Developments (442K)
Plate 3-17	Recreation Developments (388K)

Photo 1-1	April 1931 flood at Main Street, Walla Walla, Washington.
Photo 1-2	The MCP provides the public with a variety of recreational opportunities in a scenic setting.
Photo 1-3	The MCP Project Office
Photo 2-1	Walla Walla District used Intergraph® Work Stations and Software to implement GIS.
Photo 2-2	Palouse Section. The Snake River cuts through the Palouse Section, exposing basalt lava flows.
Photo 2-3	The Blue Mountains and Mill Creek Drainage Basin.
Photo 3-1	Aerial view of MCP and its environs.
Photo 3-2	1931 flood in downtown Walla Walla, Washington.
Photo 3-3	Low flows below the division works are a major contributor to poor water quality.
Photo 3-4	Algal blooms in Mill Creek Channel result from high nutrient levels and stagnation.
Photo 3-5	A variety of upland vegetation has developed on MCP in contrast to surrounding agricultural fields.
Photo 3-6	Riparian vegetation along Mill Creek Channel.
Photo 3-7	Extensive wetlands have developed behind Diversion Dam.
Photo 3-8	1949 aerial photo of MCP, prior to WDG wildlife plantings and the lake (September 14, 1949).
Photo 3-9	1987 aerial photo of MCP. The vegetation types on MCP are in sharp contrast to the surrounding area.
Photo 3-10	Wetlands on the project support a variety of amphibians, including a bullfrog in the pond at Rooks Park.
Photo 3-11	Downy woodpecker in riparian vegetation (black cottonwood).
Photo 3-12	Ducks in the Mill Creek Channel.
Photo 3-13	Great Blue Heron in Mill Creek Channel below Diversion Dam.
Photo 3-14	White-tailed deer along Mill Creek.
Photo 3-15	Upper reach of Mill Creek.
Photo 3-16	Middle reach of Mill Creek. Agricultural activities begin 3 miles north of the Washington/Oregon border.
Photo 3-17	Lower reach of Mill Creek begins at Division Works.
Photo 3-18	Virgil B. Bennington Lake at elevation 1205. Fishing is popular all year long.
Photo 3-19	Marcus Whitman (sketch from Paul Kane).
Photo 3-20	Narcissa Whitman (sketch from Paul Kane).
Photo 3-21	Hand excavation of channel under 4th Avenue Bridge (11/2/36).
Photo 3-22	Completed blanket revetment west of 6th Street Bridge (2/26/37).
Photo 3-23	Completing south blanket revetment west of 6th Street Bridge (2/26/37).
Photo 3-24	Mill Creek Diversion Dam under construction.
Photo 3-25	Mill Creek Channel and diversion site under construction (2/26/37).
Photo 3-26	Field office and soils laboratory (10/01/40). The field office occupies the project office today.
Photo 3-27	Intake canal under construction (05/27/40).
Photo 3-28	Mill Creek Dam under construction.
Photo 3-29	Mill Creek Channel under construction. Placement of concrete paving on bottom of channel.
Photo 3-30	Walla Walla Community College is adjacent to the project.
Photo 3-31	Mill Creek Project is easily accessible from Mill Creek Road and from U.S. Highway 12.
Photo 3-32	Pedestrians and bicyclists take advantage of both the foot bridge and this bridge provided on the project.
Photo 3-33	Service roads on the project also serve as informal trails for recreationalists.
Photo 3-34	The Diversion Levee prevents flooding along the flat Mill Creek floodplain.
Photo 3-35	Diversion Dam. View from South Mill creek Trail.
Photo 3-36	Debris Facilities. Two types of barriers collect debris.
Photo 3-37	Headworks allows floodwaters to move from Mill Creek to the Intake Canal.
Photo 3-38	Intake Canal facilities.
Photo 3-39	The concrete canal transports water from Mill Creek to Virgil B. Bennington Lake.
Photo 3-40	Mill Creek Dam. This 1958 photo clearly shows the earthen dam.
Photo 3-41	Mill Creek Return Canal returns floodwater stored in the lake to return to Mill Creek.
Photo 3-42	Russell Creek Return Canal is used only in emergencies.
Photo 3-43	Division Dam on Mill Creek allows water to be transferred to Yellowhawk and Garrison Creeks.
Photo 3-44	Storage building at Rooks Park.
Photo 3-45	Restroom at Rooks Park.
Photo 3-46	Wildlife habitat plantings.
Photo 3-47	Fish ladder entrance at the First Division Dam.
Photo 3-48	Boulders placed in Mill Creek Channel.
Photo 3-49	Rooks Park.
Photo 3-50	Project Office area.
Photo 3-51	Mill Creek Channel runs from Diversion Dam to the project boundary below Division Dam (this photo is only a section of the channel).
Photo 3-52	Lake Recreation Area.
Photo 3-53	Wildlife area.
Photo 3-54	Bicycling falls under the category of "other."
Photo 3-55	Picnicking is most popular in the spring at Rooks Park.
Photo 3-56	Fishing is popular in both Mill Creek and Virgil B. Bennington Lake.
Photo 3-57	Wading and swimming are popular summer activities, both in Mill Creek and at Virgil B. Bennington Lake.
Photo 3-58	Boating on Virgil B. Bennington Lake. Visitation by recreation users and sightseers is a major influence on visual resource management.
Photo 3-59	Mill Creek Dam blends into the surrounding landscape because of its color and texture.
Photo 3-60	The large old-growth cottonwoods and open lawns of Rooks Park are the major aesthetic reasons the park receives such high visitation.
Photo 3-61	Straight rows of wildlife plantings, contrasting with the natural vegetation patterns can be seen on the project. View from the top of Mill Creek Dam.
Photo 3-62	The security fence around the Project Office does not welcome the public to the project.
Photo 3-63	Trees and shrubs on the project, in contrast to the surrounding agriculture, wildlife, and the views of the Blue Mountains, contribute to the high scenic quality of MCP.

Figure 1-1	Staff Organization at Mill Creek
Figure 1-2	Project Organization Management Chart
Figure 2-1	Columbia Snake Intermountain Physiographic Province
Figure 2-2	Time and Events
Figure 2-3	Diagram Cross Section
Figure 2-4	Climate Division Areas
Figure 2-5	Regional Temperatures
Figure 2-6	Regional Precipitation
Figure 2-7	Typical Vegetation Sequence
Figure 2-8	Regional Population Urban Areas
Figure 2-9	Regional Population Ten Largest Counties
Figure 2-10	Population and Forecasts Mill Creek Market Area 1940-2002
Figure 2-11	Urban--Rural Population Distribution 1990
Figure 2-12	Age Distribution
Figure 2-13	Per Capita Income 1975 to 1990
Figure 2-14	Unemployment Walla Walla County 1980 to 1989
Figure 2-15	Job Distribution Walla Walla County 1980 to 1990
Figure 2-16	Job Distribution Walla Walla County 1980 to 1990
Figure 2-17	Employment Diversification Walla Walla County 1980 to 1990
Figure 2-18	Land Use, The MCP MA (Walla Walla--College Place Urban Areas
Figure 2-19	Recreation Facilities Within 15 Minutes of Residence
Figure 2-20	Public Recreation Lands 1993
Figure 2-21	Recreation Activities by Category
Figure 2-22	Recreation Participation of Activity Category
Figure 2-23	Activity Percent Growth Region 4 1987 to 2000
Figure 2-24	Activity Percent Growth Region 2 1987 to 2000
Figure 3-1	Mill Creek Project Altitude (feet)
Figure 3-2	Mill Creek Project Steepness of Slope
Figure 3-3	The MCP Aspect
Figure 3-4	Geologic Cross-Section
Figure 3-5	Major Geologic Faults
Figure 3-6	Geology in the MCP Environs
Figure 3-7	Mill Creek Project Soils
Figure 3-8	Gaging Stations in the Mill Creek Drainage
Figure 3-9	The MCP Runoff Volume
Figure 3-10	The MCP, Kooskooskie
Figure 3-11	Climate Station Location in the Mill Creek Basin
Figure 3-12	Mean Temperature and Precipitation, MCP
Figure 3-13	Land Cover and Vegetation
Figure 3-14	Fish of Special Concern
Figure 3-15	Original Land Survey
Figure 3-16	Portion of the Original Land Survey (Timber Reservation)
Figure 3-19	Mill Creek Project Headlines
Figure 3-20	Mill Creek Channel - Pre-Construction
Figure 3-21	Walla Walla Trail Proposed Development
Figure 3-22	Capacity Curve
Figure 3-23	Flood Control Rule Curve
Figure 3-24	Virgil B. Bennington Lake Drawdown and Refill
Figure 3-25	Visitor Activities by Season for Calculation, Rooks Park
Figure 3-26	Actual Visitor Activities Percent by Season, Rooks Park
Figure 3-27	Visitor Activity by Season for Calculation, Lake Area
Figure 3-28	Actual Visitor Activities Percent by Season, Lake Area
Figure 3-29	Visitor Activities by Season for Calculation, Levee Trail
Figure 3-30	Actual Visitor Activities by Season, Levee Trails
Figure 3-31	Mill Creek Project Annual Attendance (Visits)
Figure 3-32	Mill Creek Project Annual Visits by Area 1970, 1979, 1990, and 1993
Figure 3-33	MCP Visitation by Month and Area
Figure 3-34	Mill Creek Project 1992 Monthly Visits by Area
Figure 3-35	MCP Visitor Hours by Month and Area
Figure 3-36	Mill Creek Project 1992 Visitor Hours by Area
Figure 3-37	MCP Visitor Activities
Figure 3-38	MCP Visitor Activities
Figure 3-39	Visitor Activities by Season
Figure 3-40	Rooks Park 1992 Visitation by Activity
Figure 3-41	MCP 1992 Lake Area Visitation Activities
Figure 3-42	Levee Trails 1992 Recreation Visitation by Activity
Figure 3-43	Mill Creek Project Visitor Origin
Figure 3-44	Mill Creek Project Visits and 30 Average Max Temperature
Figure 3-45	Lake Level Influence, 1990 and 1992 Visits at Lake Area
Figure 3-46	Lake Level Influence, Annual Visits by area, 1989 to 1992
Figure 3-47	Mill Creek Project Projected Annual Attendance (Visits) 1993 to 2005
Figure 3-48	Mill Creek Project Method 4 Projected Annual Attendance (Visits) 1993-2005
Figure 4-1	Synthesis Overlay Process

Table 2-1	Regional Soils
Table 2-2	Area Distribution and Runoff Contribution for Walla Walla River (Water Years, 1970 to 1986)
Table 2-3	Water Quality Classification of Area Streams
Table 2-4	Monthly Temperatures (in degrees Fahrenheit)
Table 2-5	Annual Precipitation
Table 2-6	MCP Region Species of Concern
Table 2-7	Reserved
Table 2-8	Population Characteristics of Counties, Distributed by State
Table 2-9	Population Levels for Mill Creek MA Components
Table 2-10	Population Forecast
Table 2-11	Recreation Sites
Table 2-12	57 Outdoor Recreation Activities Ranked by Household Trips
Table 2-13	57 Outdoor Recreation Activities Ranked by Projected Growth
Table 3-1	The MCP Elevation Zone
Table 3-2	Mill Creek Project Steepness of Slope
Table 3-3	The MCP Aspect
Table 3-4	Description of MCP Soils
Table 3-5	Mill Creek at Walla Walla, Total Monthly Runoff Volume
Table 3-6	Virgil B. Bennington Lake Water Quality Data
Table 3-7	Climate Stations
Table 3-8	Walla Walla Basin Average Monthly Temperature
Table 3-9	Mill Creek Basin - Temperatures, Walla Walla FAA
Table 3-10	Reserved
Table 3-11	Mill Creek Basin - Monthly Precipitation, Walla Walla WSO
Table 3-12	Mill Creek Basin - Monthly Precipitation, Walla Walla FAA
Table 3-13	Mill Creek Basin - Monthly Precipitation - Mill Creek Dam
Table 3-14	Mill Creek Basin - Monthly Precipitation - Walla Walla 13 ESE, Oregon
Table 3-15	Mean Snowfall, 1931 - 1965 at Walla Walla WSO
Table 3-16	Virgil B. Bennington Lake—Monthly Evaporation
Table 3-17	Suspended Particulate Levels, City of Walla Walla, Annual Geometric Means
Table 3-18	The MCP Land Cover Vegetation
Table 3-19	Wildlife Inventory
Table 3-20	The MCP Boundary
Table 3-21	Ownership of Lands Within MCP
Table 3-22	Corps Easements
Table 3-23	Mill Creek Project Land Allocation
Table 3-24	Mill Creek Project Outgrants and Reservations
Table 3-25	Reserved
Table 3-26	Transportation Facilities—Roads
Table 3-27	Transportation Facilities—Trails
Table 3-28	Reserved
Table 3-29	Lake Elevations, 1976 to 1993
Table 3-30	Specific Frequency Lake Elevations
Table 3-31	MCP Fences
Table 3-32	Virgil B. Bennington Lake at Various Elevations
Table 3-33	Percent of Vehicles
Table 3-34	Number of People per Vehicle
Table 3-35	Hours Per Person
Table 3-36	Percent Used to Distribute Visitors by Activity
Table 3-37	Percent Rank Order
Table 3-38	The MCP Annual Attendance
Table 3-39	Visitation by Activity, 1991 and 1992
Table 3-40	1992 Visitation by Activity
Table 3-41	MCP Forecast Attendance
Table 3-42	MCP Attendance Projection By Area and Activity
Table 3-43	Social Capacity Calculations, Boating (Non-Motorized) at Virgil B. Bennington Lake
Table 3-44	Social Capacity Calculations, Boat Launching at Virgil B. Bennington Lake
Table 3-45	Social Capacity Calculations, Boat Fishing at Virgil B. Bennington Lake
Table 3-46	Social Capacity Calculations, Shoreline Fishing at Virgil B. Bennington Lake
Table 3-47	Social Capacity Calculations, Camping Near Rooks Park
Table 3-48	Social Capacity Calculations, Camping at Virgil B. Bennington Lake
Table 3-49	Social Capacity Calculations, Swimming at Virgil B. Bennington Lake
Table 3-50	Social Capacity Calculations, Trail Activities at Virgil B. Bennington Lake and Levee Trails
Table 3-51	Social Capacity Calculations, Picnicking at Virgil B. Bennington Lake
Table 3-52	Social Capacity Calculations, Picnicking at Rooks Park
Table 3-53	Social Capacity Summary, MCP
Table 4-1	Land Classification Attractiveness (A) and Vulnerability (V)

1.01. Mill Creek Flood Control Project

This section contains the legislative authorization, purposes, benefits, and management for the Mill Creek Flood Control Project. An in-depth history of the Mill Creek Flood Control Project up to 1949 (when construction was completed) can be found in section 3, paragraph 3.03(b) of this volume. The Mill Creek Flood Control Project was designed and constructed to protect the city of Walla Walla, Washington. It is composed of the following major units: 1) Mill Creek channel; and 2) the off-channel reservoir (Virgil B. Bennington Lake) and lands referred to as the Mill Creek Project (MCP) in this report.

a. Mill Creek Channel.

The Mill Creek Channel, or Improved Channel, runs through the city of Walla Walla. It is owned, operated, and maintained by a local municipal corporation, the Mill Creek Flood Control Zone District. The Mill Creek Flood Control Zone District is directed by the Walla Walla County Commissioners. This report does not plan for lands that contain the Mill Creek Channel, but the channel is referred to since it is part of the project.

b. Mill Creek Project.

The MCP is the portion of the Mill Creek Flood Control Project that is owned, operated, and maintained by the Federal Government. The Federal agency responsible for the operation and maintenance of MCP is the U.S. Army Corps of Engineers, hereafter referred to as the "Corps."

1.02 Project Authorization

a. General Authority.

(1) Background.

A comprehensive plan of flood protection for the city of Walla Walla, and its immediate vicinity (see photo 1-1), was approved by Congress in 1938, with some minor changes added in 1941. The plan consisted of two major construction projects: 1) the Improved Channel (of Mill Creek) through the city; and 2) the off-channel reservoir now known as Virgil B. Bennington Lake, and the lands surrounding this reservoir.

(2) The Corps Report.

In 1937, the Corps completed a report that included a comprehensive plan of flood protection for the city of Walla Walla. The plan included an off-channel reservoir and lands, along with the main channel through town, which was being constructed by Works Progress Administration (WPA) funds, with construction supervision by the Corps. The report recommended that an off-channel reservoir be built to store floodwater so that the city of Walla Walla could be fully protected. That report, and its corresponding letters of endorsement, were sent to Congress, and became House of Representatives Document (HD) 578. This document states:

"...the channel-improvement works now under construction in and adjacent to the city will afford a substantial measure of relief, but a greater degree of protection is desirable. The flood-detention reservoir and necessary auxiliary works proposed by the district engineer with the channel improvements now under construction will fully protect the city and adjoining lands against practically all flood to be anticipated." (HD 578, 1938, page 3).

(3) Public Law.

(a) Original Authorization.

The plan, including the off-channel reservoir, was approved by Congress and signed into law by President Franklin D. Roosevelt on 28 June 1938. Section 4 of the Flood Control Act of 1938 (Public Law 75-761, 75th Congress, 3d Session) specifically pertaining to Mill Creek, states:

"The plan for protection of the city of Walla Walla, Washington, and adjacent lands by means of a reservoir and related works, as set forth in House Document Numbered 578, 75th Congress, third session is approved and for the execution of this plan is hereby authorized $1,608,000."

(U.S. Congress, vol. 52, page 1222).

(b) Project Modifications.

Some minor additions were needed for the Mill Creek Flood Control Project. The Corps sent a report to Congress, along with other recommendations for the Walla Walla River. This report was included in HD 719, dated 24 April 1940, which states:

"...that it is desirable to make certain modifications in the plans for the existing project on Mill Creek at and in the vicinity of Walla Walla, Wash., authorized by the 1938 Flood Control Act..."

(U.S. Congress, 1940a, page 3.)

The specific recommended modifications to the project, as stated in HD 719, were:

"(1) ...reconstruction of bridges across Mill Creek in the city of Walla Walla...(2) additional costs of right-of-way, and (3) additional construction measures required to insure safety of the proposed earth dam."

(U.S. Congress, 1940a, page 5.)

The Flood Control Act of 1938 was amended, with the recommendations being adapted under the Flood Control Act of 1941 (Public Law 77-228, 77th Congress, 1st Session, 18 August 1941). The paragraph in the Flood Control Act of 1941 that relates to the project states:

"...the project for the protection of the city of Walla Walla, Washington, authorized by the Act approved June 28, 1938 is hereby modified in accordance with the recommendations of the Chief of Engineers in House Document Numbered 719, 76th Congress, third session, at an estimated cost of $754,000."

(c) Virgil B. Bennington Lake.

The off-channel reservoir, authorized in 1938, was referred to by the Corps as Mill Creek Reservoir from 1938 to 1972, and as Mill Creek Lake until 1992. On 31 October 1992, President George Bush signed into law (Public Law 105-580) The Water Resources Development Act of 1992. This act renamed the reservoir, authorized in 1938, as Virgil B. Bennington Lake. The new law states:

"(h) Mill Creek Reservoir, Washington. --

(1) Designation.-The Mill Creek Reservoir, authorized by section 4 of the River and Harbor Act of June 28, 1938 (52 Statute 1222), shall hereafter be known and designated as the "Virgil B. Bennington Lake."

(2) Legal References.-A reference in any law, regulation, document, record, map, or other paper of the United States to the reservoir referred to in the Paragraph (1) shall be deemed to be a reference to the "Virgil B. Bennington Lake.""

A biographical sketch of Virgil B. Bennington can be found in section 3, paragraph 3.03(b) of this volume.

b. Recreation Authority.

Recreation development was authorized at MCP under Section 4 of the Flood Control Act of 1944 (Public Law 78-534, 78th Congress, 2d Session). This act was passed on 22 December 1944, and amended by the Flood Control Acts of 1946, 1954, and 1962. This act authorized the Corps:

"...to construct, maintain, and operate public park and recreational facilities at water resource development projects under the control of the Secretary of the Army, and to permit the construction, maintenance, and operation of such facilities."

The Flood Control Act of 1944 provides for the water areas of the project to be open to public use (i.e., boating, fishing, and other recreational purposes). It also provides for ready access to and from areas along the shores of the project that will be maintained for general use when in the public interest (USACE, 1989, page 17-1).

c. Fish and Wildlife Authority.

The Fish and Wildlife Coordination Act of 1958 (Public Law 85-624) states that fish and wildlife conservation will receive equal consideration with other project purposes, and be coordinated with other features of water resource development.

Approximately 60 acres of MCP were purchased as part of the Lower Snake River Fish and Wildlife Compensation Plan, which was authorized by the Water Resource Development Act of 1976 (Public Law 94-587, 94th Congress, 2d Session, 22 October 1976). These lands were transferred to MCP on 7 July 1992.

A synopsis of applicable laws and regulations can be found in Supporting Data, Item 2, in the back of this report.

1.03. Project Purpose.

a. Flood Control.

The original purpose of the Mill Creek Flood Control Project was to control periodic flooding from Mill Creek and, thus, prevent extensive damages to the city of Walla Walla and the agricultural lands in the vicinity. Historically, several damaging floods have had disastrous effects on the city of Walla Walla and the lands lying downstream. The MCP was constructed for the most severe flooding.

b. Recreation.

The Federal Water Project Recreation Act of 1965 (Public Law 89-72, 89th Congress, 1st Session, 9 July 1965), as amended, established recreational potential at Mill Creek Flood Control Project as a full project purpose (see photo 1-2).

1.04. Project Benefits.

a. General.

The tangible benefits of the Mill Creek Flood Control Project are reduction of flood losses, increase in land use, and recreational use (including hunting and fishing). Intangible benefits include fish and wildlife values (i.e., wildlife viewing, migratory species nesting/feeding and breeding/brooding, and habitat for non-game animals), and the prevention of probable loss of life and property during a major flood event.

b. Flood Control.

Between 1942 and 30 September 1992, the Mill Creek Flood Control Project has prevented $10,818,000 in cumulative flood damages. The channel through the city has prevented $10,761,000 in damages, and the lake project has prevent $57,000 (USACE, 1993).

c. Fish and Wildlife.

Fish and wildlife values are considered an intangible benefit. The MCP provides fish habitat for 22 species of fish, including wild trout and steelhead, hatchery trout and steelhead, non-salmonids, and spiny ray fish. The project also provides habitat for 170 species of wildlife. The fish and wildlife present provide visitors with educational, observational, recreational, and aesthetic experiences.

d. Recreation.

Fishing on the project has been allowed since 1954. Park and recreation facilities were opened to the public on 1 July 1964. Recreational pursuits are served through the maintenance of a well-equipped, day-use park; management of hunting lands; and the development of a trail system for hikers, equestrians, and bicyclists. Over the last 20 years (1973 to 1992), there have been 3.6 million visitors at MCP. The offstream reservoir also provides water-based recreational opportunities. All recreational activities are considered incidental to flood control, and no specific tangible benefits are assigned (USACE, 1992).

1.05. Project Management.

The Mill Creek Flood Control Project is operated in a cooperative agreement between the Corps and the Mill Creek Flood Control Zone District (local authority). The project is operated under written agreement. The MCP is Federally owned, and operated and maintained by the Corps. The Mill Creek Channel portion is owned, operated, and maintained by Mill Creek Flood Control Zone District, but the first mile of the channel is part of MCP. The Corps, in cooperation with the local authority, has developed the water control manual for the operation of the project. Section 3, paragraph e., of this volume contains a more in-depth description of the water resource facilities and operations of the project.

a. General.

(1) Project Office.

Mill Creek is operated under the direction of the Project Manager, who is located at the project office (see photo 1-3). The Project Manager is directly responsible to the Chief, Operations Division, U.S. Army Corps of Engineers, Walla Walla District. The Project Manager coordinates project activities with the District Office's Planning, Engineering, Construction, and Real Estate Divisions. Project personnel are responsible for maintenance, management, and supervision of the project facility, equipment, and the natural resource management program. Project staff are also local representatives for the Corps. They supervise the use of the lands and waters of the project area, protect and maintain Government property, and ensure high standards of public health and safety.

The Project Manager at Mill Creek is concerned with applying the principles of sound resource management, and assuring that the goals for such management are achieved.

(2) District Office.

The Walla Walla District Office, Walla Walla, Washington, is available to support the project as necessary. The Walla Walla District boundaries follow the Snake River Drainage for approximately 115,000 square miles. The District Office is responsible for assuring that the Project Office is fully informed on pertinent policy issues, providing budget support, and assisting in planning, designing, and building facilities. Figures 1-1 and 1-2 illustrate how MCP and other elements are organized within the Walla Walla District. The primary element supporting the project is Operations Division. Other major elements are Planning Division: Hydrology Branch (flood control operations); Environmental Resources Branch (project master plan, water quality, archaeological and historical resources, and environmental compliance); Engineering Division: Design and Geotechnical Branches (design and technical assistance); and Real Estate Division (land outgrants and real property).

b. Mill Creek Channel

The "improved" channel was constructed using Federal, State, and local funding. The channel is owned by, and located in, the Mill Creek Flood Control Zone District, Walla Walla, Washington. The channel is operated in cooperation with the Corps, per the Water control Manual for the Mill Creek Flood Control Project that was developed by the Corps (USACE, 1991).

The Mill Creek Flood Control Zone District has the authority to collect revenue needed to operate and maintain the channel, as directed by the Board of Directors (County Commissioners) and in agreement with the Corps. As the local sponsor, the Flood Control Zone District is responsible for normal operations and maintenance.

The Corps is authorized to provide rehabilitation for the channel, since it is part of the plan and project, as authorized by the Flood Control Act of 1938.

1.06. References

USACE, 1982

Mill Creek Lake, Washington Design Memorandum No. 7, Main Channel Rehabilitation, Walla Walla, Washington, Walla Walla District.

USACE, 1989

Digest of Water Resources Policies and Authorities, EP 1165-2-1, 15 February 1989, Washington, D.C.

USACE, 1991

Water Control Manual for Mill Creek Flood Control Project, Mill Creek, Washington. Planning Division, Hydrology Branch, Walla Walla, Washington, Walla Walla District.

USACE, 1992

Project Attendance Figures, Personal Communication, Linda Carter, Natural Resources Branch, Operations Division, Walla Walla District, Walla Walla, Washington.

USACE, 1993

Damages Prevented by Existing Projects, Paul C. Fredericks and Gina Trafton, Walla Walla District, Walla Walla, Washington.

United States Congress (USC), 1938

Mill Creek, Washington, House of Representatives Document 578, 75th Congress, 3d Session, Mill Creek, Washington, United States Government Printing Office.

USC, 1938

The Flood Control Act of 1938, Public Law 75-761, 75th Congress, 3d Session, 28 June 1938.

USC, 1940

Walla Walla River and Tributaries, Oregon and Washington, House of Representatives Document No. 719, 76th Congress, 3d Session, 24 April 1940, United States Government Printing Office.

USC, 1941

The Flood Control Act of 1941, Public Law 77-228, 78th Congress, 1st Session, 18 August 1941.

USC, 1944

The Flood Control Act of 1944, Public Law 78-534, as amended by the Flood Control Act of 22, December 1944, 1946, 1954, and 1962.

USC, 1958

Fish and Wildlife Coordination Act of 1958, Public Law 85-624, 85th Congress, 2d Session, 12 August 1958.

USC, 1965

The Federal Water Project Recreation Act of 1965, Public Law 89-72, 89th Congress, 9th Session, 9 July 1965, as amended.

USC, 1976

Water Resource Development Act of 1976, Public Law 94-587, 94th Congress, 2d Session, 22 October 1976.

USC, 1992

Water Resources Development Act of 1992, Public Law 102-580, 102d Congress, 2d Session, 30 October 1992.

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