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COLORADO WATER CONSERVATION BOARD 102 Columbine Building 1845 Sherman Street Denver, Colorado 80203

M E M O R A N D U M

SUBJECT: Status of Flood Plain Information Program in Colorado June 1974

Increasing recognition of the importance of Colorado's flood plains is occurring. Colorado Revised Statutes 1963, as amended, Section 149-1-11(4), authorizes the Colorado Water Conservation Board to designate and approve storm or flood water runoff channels and to make such designations available to legis­ lative bodies of local jurisdictions. In addition to assisting local governmental entities in obtaining basic flood plain data, the Board is actively engaged in assisting local governments in developing and adopting effective flood plain ordinances and related land use regulations. The Board has the responsibility of coordinating all flood related studies within the state of Colorado, which includes scheduling the Flood Plain Information Studies conducted by federal agencies, and can provide direct financial assistance for a study within Colorado. The intent is that, with these data outlining the flood plains, local entities can control the use of these flood plains and thereby prevent developments within the paths of future floods. The U.S. Army Corps of Engineers and the Soil Conservation Service, U. S. Department of Agriculture, have specific authorities for the preparation of detailed flood plain reports.

House Bill 1041, relating to the use of land, (Article 7, Chapter 106, CRS 1963, as amended) provides, "Flood­ plains shall be administered so as to minimize significant hazards to public health and safety or to property. Open space activities shall be encouraged in the floodplains." Concerning the designation and use of flood plains, the Board is charged with responsibilities under the Act as follows:

1. To promulgate a model flood plain regulation no later than September 30, 1974. 2. To identify in general terms flood plain hazard areas by June 30, 1976. 3. To assist local governments on a continuing basis in the specific identification of flood plain hazard areas. 4. To assist local governments on a continuing basis in determining what use and occupation may be permitted in designated flood plain hazard areas. The demand for Flood Plain Information Studies has been greater than the funds appropriated to the Corps of Engineers; therefore, to expedite the studies, the Omaha and Albuquerque Districts and the Soil Conservation Service have made a practice of requiring )the local entities to contribute toward these studies by providing funds or services toward, or actually doing, the necessary field surveys. The Soil Conservation Service requires the local entities to contribute toward the production of the necessary maps and reproduction of the completed report.

It is the practice of the Board to assign a high priority to the requests for Flood Plain Information Studies for streams where urban development in the flood plains appears imminent, with due consideration to the order in which the applications are received.

The Flood Plain Information Reports completed by the Corps of Engineers in Colorado to date are as follows:

1. Denver Metropolitan Region Series

a. Volume I, South Platte River, Waterton to Brighton, October 1963

b. Volume II, Sand, Toll Gate and Lower Cherry Creeks, April 1964

c. Special Flood Hazard Report to Revise Volume II, Sand, Toll Gate and Lower Cherry Creeks, July 1971

d. Volume III, Bear and Clear Creeks, January 1966

e. Special Flood Hazard Report to Revise Volume III, Bear Creek, December 1972

f. Volume IV, Big Dry Creek, Little Dry Creek (Arapahoe County), Greenwood Gulch, Weir Gulch, Lakewood Gulch, South Lakewood Gulch, Mcintyre Gulch, Little Dry Creek (Adams County), Grange Hall Creek, October 1968

g. Volume V, Ralston Creek, Leyden Creek, Van Bibber Creek, Lena Gulch, Sanderson Gulch and North Sanderson Gulch, November 1970

Memorandum 2 June 1974 h. Volume VI, Goldsmith Gulch, Dutch Creek, Lilley Gulch and Coon Creek, October 1971

i. Bear Creek and Mount Vernon Creek, Morrison, Colorado, October 1971

j. Special Flood Hazard Report Upper Toll Gate Creek and Tributaries, Aurora, Colorado, June 1973

2. Boulder County Series

a. Volume I, Left-Hand Creek, January 1969

b. Volume II, Boulder Creek and South Boulder Creek, August 1969

c. Volume III, Lower St. Vrain Creek, June 1972

d. Volume IV, Upper St. Vrain Creek, September 1972

e. Boulder Creek, City of Boulder, Special Flood Hazard Information Report, May 1972

3. Studies and Reports for Areas outside the Denver Metropolitan Area

a. North Fork Republican River, Wray, Colorado, June 1969

b. Fountain Creek, Pueblo, Colorado, October 1968

c. Goodnight Arroyo, Dry Creek and Wild Horse-Dry Creek, Pueblo, Colorado, April 1969

d. St. Charles River, Pueblo, Colorado, March 1970

e. Rio Grande River, Monte Vista, Colorado, June 1969

f. Monument Creek, Colorado Springs, Colorado, May 1971

g. Big Thompson River at Loveland, Colorado, December 1971

Memorandum 3 June 1974 h. Colorado and Gunnison Rivers, Grand Junction, Colorado, March 1973

i. Colorado River and Rifle, Government and Hubbard Gulch Creeks, Rifle, Colorado, April 1973

j. Roaring Fork River and Castle and Hunter Creeks, Aspen, Colorado, June 1973

k. Fountain and Jimmy Camp Creeks, Colorado Springs, Fountain, and El Paso County, Colorado, March 1973

1. Upper Toll Gate Creek and Tributaries, Aurora, Colorado, June 1973

m. Volume I, Cache La Poudre: River, Fort Collins and Larimer county, Colorado, October 1973

n. Volume II, Cache La Poudre River, Greeley and Weld County, Colorado, March 1974

The Soii ·Conservation Service has completed the following Flood Plain Information Reports in Colorado:

1. Boxelder Creek, near Wellington, Colorado, to Cache La Poudre River, May 1970

2. Sand Creek, Tributary of Fountain Creek, Colorado Springs, Colorado, July 1973

The Urb.an . Dr~inage and Flood Control District has completed the Flood Plain Information Reports for the following Denver­ Boulder, Colorado, areas:

1. Volumes I and II, Big Dry Creek, Major Drainage Planning, Adams County and Jefferson County and Westminister, Colorado, March 1973

2. Volumes I and II, South Boulder Creek, Major Drainage Planning, Boulder and Boulder County, Colorado, December 1973

3. · Volumes I and II, Little Dry Creek, Major Drainage Planning, Arapahoe County, Englewood, Dougla s County, Che rry Hills Village, Gr e enwood Village, Colorado February 1974

Memorandum -4- June 1974 ,

4. Niver Creek, Water and Drainage Report, Adams County, Federal Heights and Thornton, Colorado, February 1974

The Wright-McLaughlin Engineers, Consulting Engineers, Denver, Colorado, has prepared for the city of Boulder, Colorado, Flood Plain Information Reports for tributary streams of Boulder Creek, Colorado, as follows:

1. Lower Sunshine Gulch, Boulder, Colorado, September 1969

2. Volumes 1 and 2, Pilot Planning Study, Major Drainageways in North Boulder, Boulder, Colorado, 1969

a. Four-mile Creek b. Wonderland Creek c. Elmers Two-Mile Creek d. Two-Mile Creek e. Goose Creek

3. Volumes 1 and 2, Urban Storm Drainage, Major · Drainageways in South Boulder, Boulder, Colorado 1969

a. Gregory Creek b. Bluebell Canyon Creek c. King Gulch d. Skunk Creek e. Bear Canyon Creek f. Viele Channel g. Anderson Channel h. Davids Draw

The Flood Plain Information Studies now under way, or that have been scheduled, are listed below with the target dates for completion. Budget constraints may alter the target dates. The studies are being made by federal, state, and local agencies. The studies being made by the Corps of Engineers are listed by the district office conducting the study.

U. S. Army Corps of Engineers

1. Omaha District

Memorandum -5- June 1974 ,

Active Studies

a. Volume III, Cache La Poudre River, between Fort Collins and Greeley, Colorado, FY 1975

b. Big Thompson River, Main Stream, Larimer County, Colorado, FY 1975

Studies Requested

c. The Urban Drainage and Flood control District, Denver, Colorado, as part of its project REUSE, has separated the District into drainage basins and requested the Corps of Engineers to prepare Flood Plain Information Reports for the streams and gulches in these basins. Listed below in the order of priority requested are the basins with the number of tributaries in each basin. The dates of completion of these reports have not been scheduled.

(1) Bear Creek - 4 tributaries (2) South Side Area - 8 tributaries (3) First Creek - 6 tributaries (4) Central Denver Area - 3 tributaries (5) Clear Creek - 4 tributaries (6) Cherry Creek - 2 tributaries (7) Boulder Creek - 3 tributaries (8) Big Dry Creek - 1 tributary

d. Little Thompson River, · Main Stream, Larimer County, Colar~do

e. Hydrological Analysis of the May 6-11, 1973, Flood

f. South Platte River, within the boundaries of Weld county

Pending Study Request

g. Cherry Creek, ·Upstream of the Cherry Creek Reservoir

Memorandum -6= June 1974 I

2. Tulsa District

There are no Active or Requested Studies at the present time.

3. Kansas City District

There are no Active or Requested Studies at the present time.

Pending Study Requests

a. French Creek, Holyoke, Colorado

b. Arikaree River, Cope, Colorado

c. North Fork of the Republican River, from Wray to state line, Yuma County, Colorado

d. Arikaree River, Beecher Island, Colorado

e. South Fork of the Republican River.--Hale, Colorado

4 . Albuquerque District

Active Studies

a. Purgatorie River and Tributaries, Trinidad, Colorado, FY 1974

b. Fountain Creek, Colorado Springs west through Manitou Springs, Colorado, FY 1975

c. Rio Grande, Alamosa, Colorado, FY 1975

d. Cottonwood Creek, Colorado Springs and El Paso County, Colorado, FY 1975

e. Six-Mile Creek, Pueblo, Colorado, FY 1975

f. Salt Creek, Pueblo, Colorado, FY 1976

g. Huerfano River, Pueblo, Colorado, FY 1976

Memorandum -7~ June 1974 h. Chico Creek, Pueblo, Colorado, FY 1976

5. Sacramento District

Active Studies

a. Durango, Colorado, Area, covering portions of Animas River, Lighter and Junction Creeks, FY 1974

b. Upper Roaring Fork River, Aspen, Colorado FY 1975

c. Steamboat Springs, Colorado, Area, covering porti ons of the following streams: Yampa River, Soda Creek, Fish Creek, Butcherknife Creek, Spring Creek, Burgess Creek, and Walton Creek, FY 1975

Studies Requested

d. Colorado River at Fruita, Colorado

e. Yampa River and Tributaries, Craig, Colorado

f. White River at Meeker, Colorado

g. Colorado River at Palisade, Colorado

h. White River at Rangely, Colorado

i. Uncompahgre River and Tributaries, Montrose, Colorado

j . Animas River and Hermosa Creek, Hermosa, Colorado

k. Gunnison and Uncompahgre -Rivers, Delta, Colorado

1. Big Dry Creek at Hayden, Colorado

m. Slate River and Coal Creek, Crested Butte, Colorado

Memorandum -8- June 1974 I

n. Dolores River, Dolores and Montezuma County, Colorado

o. Crystal River, Slate and Carbonate Creeks, Marble, Colorado

p. North Fork of the Gunnison River, from Paonia to Lazear, approximately 15 miles

q. North Fork of the Gunnison River, from A1.1stin to the junction of the Gunnison and the Uncompahgre, approximately 7 miles

Pending Study Request

r. Gunnison River, Gunnison, Colorado

Soil Conservation Service

Active Studies

a. Jimmy Camp Creek, Colorado Springs, Colorado, FY 1975

b. Coal Creek, Superior, Louisville, Lafayette, Erie, Boulder County and Weld County, Colorado, FY 1975

Studies Requested

c. Uncompahgre River, Ouray, Colorado

d. Vallecito Creek, above Valecito Reservoir, La Plata County, Colorado

e. San Juan River. within the Pagosa Springs Area, Colorado

f. Pine River, near Bayfield, Colorado

g. La Plata River, La Plata County, Colorado

h. Florida River, La Plata County, Colorado

i. Cedar Creek, south and east of Montrose, Colorado

Memorandum -9- June 1974 j. Uncompahgre River, from the junction with the Gunnison River to 4 miles south of Montrose, approximately 26 miles, Delta County and Montrose County, Colorado

Colorado Water conservation Board

The Board is preparing a post-flood information report of the May 6-11, 1973, flood on ~he South Platte River for Adams County, Arapahoe County, Denver County, and Weld County, Colorado.

The Board has a program of direct financial assistance for the delineation of flood hazard areas in an amount not to exceed 50 percent of any required local costs. Studies that the Board is assisting are the following:

Active Studies

a. Upper Roaring Fork River, Aspen, Colorado

b. Rio Grande, Alamosa, Colorado

c. Blue River, Breckenridge and Summit County, Colorado

Pending Study Request

d. Gore Creek, Vail, Colorado

Upon approval and designation of storm or flood water runoff channels or basins, the Board officially notifies the local governments of the availability of the data for zoning and flood plain regulations. Section 139-60-1, CRS 1963, as amended, pro­ vides that such cities, towns, incorporated areas, and local jurisdictions shall provi de zoning regulations for any designated flood hazard areas. Sections 106-2-10 through 12, CRS 1963, as amended, provide that counties shall have the authority to flood plain zone or regulate.

It is the practice of the Colorado Water conservation Board, upon the request of the sponsoring agency and after a review and a recommendation of the Board's staff, to pass a resolution designating and approving the storm and flood water runoff channels as presented in each report for the Intermediate Regional Flood, or the flood that could be expected to occur on an average of once

Memorandum -10- June 1974 I in 100 years. The exceptions were Volumes I, II, and III of the Denver Metropolitan series, which were approved for the areas inundated by the Standard Project Flood. A Standard Project Flood is the flood that may be expected from the most severe combination of meteorological and hydrological conditions that are considered reasonably characteristic of the geographical area in which the drainage basin is located, excluding extremely rare combinations. The flood plains presented in all the completed reports listed above have been approved by resolutions by the Colorado Water Conservation Board.

During past years, this office has received inquiries from regional planning commissions, county commissioners, city officials, and others regarding obtaining Flood Plain Information Studies for flood-prone areas in their areas of jurisdiction. No priorities have been established for many of these proposed studies because of a reluctance of this office to establish a priority for a study beyond about two years. Also, in many cases, the sponsors were unable to furnish their share of the costs for the study.

LFL:tam

Memorandum -11- June 1974