33 CFR 222.6 - National Program for Inspection of Non-Federal Dams.

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§ 222.6 National Program for Inspection of Non-Federal Dams.
(a) Purpose. This regulation states objectives, assigns responsibilities and prescribes procedures for implementation of a National Program for Inspection of Non-Federal Dams.
(b) Applicability. This regulation is applicable to all Divisions and Districts having Civil Works functions.
(c) References.
(1) The National Dam Inspection Act, Pub. L. 92-367, 8 August 1972.
(2) Freedom of Information Act, Pub. L. 87-487, 4 July 1967.
(3) ER 500-1-1.
(d) Authority. The National Dam Inspection Act, Public Law 92-367, 8 August 1972 authorizes the Secretary of the Army, acting through the Chief of Engineers, to carry out a national program of inspection of non-Federal dams for the purpose of protecting human life and property.
(e) Scope. The program provides for:
(1) An update of the National Inventory of Dams.
(2) Inspection of the following non-Federal dams (the indicated hazard potential categories are based upon the location of the dams relative to developed areas):
(i) Dams which are in the high hazard potential category (located on Federal and non-Federal lands).
(ii) Dams in the significant hazard potential category believed by the State to represent an immediate danger to the public safety due to the actual condition of the dam.
(iii) Dams in the significant hazard potential category located on Federal lands.
(iv) Specifically excluded from the national inspection program are:
(A) Dams under the jurisdiction of the Bureau of Reclamation, the Tennessee Valley Authority, the International Boundary and Water Commission and the Corps of Engineers and
(B) Dams which have been constructed pursuant to licenses issued under the authority of the Federal Power Act, and
(C) Dams which have been inspected within the 12-month period immediately prior to the enactment of this act by a State agency and which the Governor of such State requests be excluded from inspection.
(f) Objectives. The objectives of the program are:
(1) To update the National Inventory of Dams by 30 September 1980.
(2) To perform the initial technical inspection and evaluation of the non-Federal dams described in paragraph 222.8(e) of this section to identify conditions which constitute a danger to human life or property as a means of expediting the correction of hazardous conditions by non-Federal interests. The inspection and evaluation is to be completed by 30 September 1981.
(3) To obtain additional information and experience that may be useful in determining if further Federal actions are necessary to assure national dam safety.
(4) Encourage the States to establish effective dam safety programs for non-Federal dams by 30 September 1981 and assist the States in the development of the technical capability to carry out such a program.
(g) Program execution—
(1) Responsibilities.
(i) The owner has the basic legal responsibility for potential hazards created by their dam(s). Phase II studies, as described in Chapter 4, Appendix D, and remedial actions are the owner's responsibility.
(ii) The State has the basic responsibility for the protection of the life and property of its citizens. Once a dam has been determined to be unsafe, it is the State's responsibility to see that timely remedial actions are taken.
(iii) The Corps of Engineers has the responsibility for executing the national program. The Federal program for inspection of dams does not modify the basic responsibilities of the States or dam owners. The Engineering Division of the Civil Works Directorate is responsible for overall program goals, guidance, technical criteria for inspections and inventory and headquarters level coordination with other agencies. The Water Resources Support Center (WRSC) located at Kingman Building, Fort Belvoir, Virginia 22060 is responsible for:
(A) Program Coordination of both the inventory and inspection programs.
(B) Developing and defining functional tasks to achieve program objectives.
(C) Determining resource requirements. (Budget)
(D) Compiling and disseminating progress reports.
(E) Monitoring and evaluating program progress and recommending corrective measures as needed.
(F) Collecting and evaluating data pertaining to inspection reports, dam owners' responses to inspection report recommendations, attitudes and capabilities of State officials, State dam safety legislation, Architect-Engineer performance, etc., for defining a comprehensive national dam safety program.
(G) Responding to Congressional, media, scientific and engineering organization and general public inquiries.
Division and District offices are responsible for executing the program at the State level. Assignment of Division reponsibilities for States is shown in Appendix A.
(2) State participation. Where State capability exists, every effort should be made to encourage the State to execute the inspection program either with State personnel or with Architect-Engineer (A-E) contracts under State supervision. If the State does not have the capability to carry out the inspection program, the program will be managed by the Corps of Engineers utilizing Corps employees or contracts with A-E firm.
(h) Update of National Inventory of Dams. (RCS-DAEN-CWE-17/OMB No. 49-RO421)
(1) The National Inventory of Dams should be updated and verified to include all Federal and non-Federal dams covered by the Act. Those dams are defined as all artificial barriers together with appurtenant works which impound or divert water and which: (1) Are twenty-five feet or more in height or (2) have an impounding capacity of fifty acre-feet or more. Barriers which are six feet or less in height, regardless of storage capacity or barriers which have a storage capacity at maximum water storage elevation of fifteen acre-feet or less regardless of height are not included.
(2) Inventory data for all dams shall be provided in accordance with Appendix B.
(3) The hazard potential classification shall be in accordance with paragraph 2.1.2 Hazard Potential of the Recommended Guideline for Safety Inspection of Dams (Appendix D to this section).
Table 2—Hazard Potential Classification
Category Urban development Economic loss
Low No permanent structure for human habitation Minimal (Undeveloped to occasional structures or agriculture).
Significant No urban development and no more than a small number of habitable structures Appreciable (Notable agriculture, industry or structures).
High Urban development with more than a small number of habitable structures Excessive (Extensive community, industry or agriculture).
(4) As in the original development of the inventory, the States should be encouraged to participate in the work of completing, verifying and updating the inventory. Also, when available, personnel of other appropriate Federal agencies should be utilized for the inventory work on a reimbursable basis. Work in any State may be accomplished:
(i) Under State supervision utilizing State personnel or Architect-Engineers contracts.
(ii) Under Corps supervision utilizing Corps employees, employees of other Federal agencies or Architect-Engineer contracts.
(5) A minimum staff should be assigned in Districts and Divisions to administer and monitor the inventory activities. Generally, the work should be accomplished by architect-engineers or other Federal agency personnel under State or Corps supervision. Corps personnel should participate in the inventory only to the extent needed to assure that accurate data are collected.
(6) The National Inventory of Dams computerized data base in stored on the Boeing Computer Services (BCS) EKS computer system in Seattle, Washington. The data base uses Data Base Management System 2000 and is accessible for query by all Corps offices.
(7) Appendix B indicates details on accessing and updating inventory data.
(8) Appendix I describes the procedure for using NASA Land Satellite (LANDSAT) Multispectral Scanner data along with NASA's Surface Water Detection and Mapping (DAM) computer program to assist in updating and verifying and National Inventory of Dams.
(9) All inventory data for dams will be completed and verified utilizing all available sources of information (including LANDSAT overlay maps) and will include site visitation if required. It is the responsibility of the District Engineer to insure that the inventory of each State within his area of responsibility is accurate and contains the information required by the General Instructions for completing the forms for each Federal and non-Federal dam.
(i) [Reserved]
(j) Inspection Program. (RCS-DAEN-CWE-17 and OMB No. 49-RO421)
(1) Scheduling of inspections. The Governor of each State or his designee will continue to be involved in the selection and scheduling of the dams to be inspected. Priority will be given to inspection of those dams considered to offer the greatest potential threat to public safety.
(i) No inspection of a dam should be initiated until the hazard potential classification of the dam has been verified to the satisfaction of the Corps. Dams in the significant hazard category should be inspected only if requested by the State and only then if the State can provide information to show that the dam has deficiencies that pose an immediate danger to the public safety. Guidance for the selection of significant category non-Federal dams on Federal lands will be given in the near future.
(ii) Selection for inspection of non-Federal dams located on Federal lands or non-Federal dams designed and constructed under the jurisdiction of some Federal agency, should be coordinated with the responsible Federal agency. The appropriate State or regional representative of the Federal agency also should be contacted to obtain all available data on the dam. Representatives of the agency may participate in the inspection if they desire and should be given the opportunity to review and comment on the findings and recommendations in the inspection report prior to submission to the Governor and the dam owner. Examples of such dams are: non-Federal dams built on lands managed by National Forest Service, Bureau of Land Management, Fish and Wildlife Service, etc.; non-Federal dams designed and constructed by the Soil Conservation Service of the U.S. Department of Agriculture; high hazard mine tailings and coal mine waste dams under the jurisdiction of the Mine Safety and Health Administration, Department of Labor.
(iii) Indian-owned dams on trust lands are considered to be non-Federal dams. All dams in the high hazard potential category will be inspected. Privately-owned dams located on Indian lands are to be included in the program, however BIA-owned dams on Indian lands are Federal dams and are exempt.
(2) Procedures. The Division Engineer is responsible for the quality of inspections and reports prepared by the District Engineer. Close liaison between the District Engineer and the State agency or A-E firm responsible for the inspections will be required in order to obtain a dependable result. To avoid undesirable delays in the evaluation of safety of individual dams, contracts with A-E's or agreements with States which are managing the program will provide that reports be completed and furnished to the District Engineer within a specified time after completion of the on-site inspection of the dam.
(i) Inspection guidelines. The inspection should be conducted in accordance with the Recommended Guidelines for Safety Inspection of Dams (Appendix D to this section). Expanded Guidance for Hydrologic and Hydraulic Assessment of Dams is provided in Appendix C. The criteria in the recommended guidelines are screening criteria to be used only for initial determinations of the adequacy of the dam. Conditions found during the investigation which do not meet the guideline recommendations should be assessed as to their importance from the standpoint of the degree of risk involved.
(ii) Coordinators. Experience has shown that coordination and communications among technical disciplines, Public Affairs Office, emergency officials, training officers, operations personnel, State representatives and A-E firms has been best in those districts where one person was delegated the responsiblity for coordinating the actions of all involved elements. Each district should evaluate its overall coordination procedures to insure that all involved elements have the best possible access to necessary data.
(iii) Field investigations should be carried out in a systematic manner. A detailed checklist or inspection form should be developed and used for each dam inspection and appended to the inspection report. The size of the field inspection team should be as small as practicable, generally consisting of only one representative of each required discipline in order to control the costs of the inspection without sacrificing the quality of the inspection. The inspection team for the smaller less complex dams should be limited to two or three representatives from appropriate technical areas with additional specialists used only as special conditions warrant. The larger more complex projects may require inspection teams of three or four specialists. Performance of overly detailed and precise surveys and mapping should be avoided. Necessary measurement of spillway, dam slopes, etc. can generally be made with measuring tapes and hand levels.
(iv) Additional engineering studies. Dam inspections should be limited to Phase I investigations as outlined in Chapter 3 of Appendix D. However, if recommended by the investigating engineer and approved by the District Engineer, some additional inexpensive investigations may be performed when a reasonable judgment on the safety of the dam cannot be made without additional investigation. Any further Phase II investigation needed to prove or disprove the findings of the District Engineer or to devise remedial measures to correct deficiencies are the responsibility of the owner and will not be undertaken by the Corps of Engineers.
(v) Assessment of the investigation.
(A) The findings of the visual inspection and review of existing engineering data for a dam shall be assessed to determine its general condition. Dams assessed to be in generally good condition should be so described in the inspection report. Deficiencies found in a dam should be described and assessed as to the degree of risk they present. The degree of risk should consider only loss of life and/or property damage resulting from flooding due to dam failure. Loss of project benefits i.e., municipal water supply, etc., should not be considered. If deficiencies are assessed to be of such a nature that, if not corrected, they could result in the failure of the dam with subsequent loss of life and/or substantial property damage, the dam should be assessed as “Unsafe.” If the probable failure of an “Unsafe” dam is judged to be imminent and immediate action is required to reduce or eliminate the hazard, the “unsafe” condition of the dam should be considered an “emergency.” If the probable failure is judged not to be imminent, the “unsafe” condition should be considered a “non-emergency.”
(B) Adequacy of spillway. The “Recommended Guidelines for Safety Inspection of Dams,” Appendix D, provide current, acceptable inspection standards for spillway capacity. Any spillway capacity that does not meet the criteria in the “Guidelines” is considered inadequate. When a spillway's capacity is so deficient that it is seriously inadequate, the project must be considered unsafe. If all of the following conditions prevail, the Governor of the State shall be informed that such project is unsafe:
(1) There is high hazard to loss of life from large flows downstream of the dam.
(2) Dam failure resulting from overtopping would significantly increase the hazard to loss of life downstream from the dam over that which would exist just before overtopping failure.
(3) The spillway is not capable of passing one-half of the probable maximum flood without overtopping the dam and causing failure.
Classification of dams with seriously inadequate spillways as “unsafe, non-emergency” is generally a proper designation of the urgency of the unsafe condition. However, there may be cases where the spillway capacity is unusually small and the consequences of dam overtopping and failure would be catastrophic. In such cases, the unsafe dam should be classified as an emergency situation.
(vi) All inspection reports will receive one level of independent review by the Corps. If the reports are prepared by the Corps, the independent review may be performed internally within the district office. However, in cases which involve significant economic, social or political impacts and technical uncertainties in evaluating the dams, advice may be obtained from the staffs of the Division Engineer and the Office, Chief of Engineers.
(3) Reports—
(i) Preparation. A written report on the condition of each dam should be prepared as soon as possible after the completion of the field inspection and assessment. A suggested report format is attached as Appendix E. It is important that the inspection report be completed in a timely manner. For inspections being done by Corps employees, it is suggested that once an inspection team has been assigned to a dam inspection it be allowed to complete the inspection and report without interruption by other work.
(ii) Review and approval. The coordinating engineer should determine which disciplines should review the report and establish a procedure to accomplish the review in a timely manner. A review panel, made up of the appropriate Division and Branch Chiefs has worked well in some districts. Use of a review panel should be seriously considered by all districts. All inspection reports shall be approved by the District Engineer who will maintain a complete file of final approved reports. Any State or Federal agency having jurisdiction over the dam or the land on which the dam is built should be given the opportunity to review and comment on the report prior to submission to the Governor or dam owner. The District Engineer will transmit final approved reports to the Governor of the State and the dam owner (or the Governor only, when requested in writing by State officials). If the report is initially furnished to the Governor only, a period of up to ten days may be allowed before the report is furnished to the dam owner. If the Governor or the owner indicates additional technical information is available that might affect the assessment of the dam's condition, the District Engineer will furnish the proposed final report to the Governor and the owner and establish a definite time period for comments to be furnished to the District Engineer prior to report approval.
(iii) In general the Governor will be responsible for public release of an inspection report and for initiating any public Statements. However, an approved report must be treated as any other document subject to release upon request under the Freedom of Information Act. The letters of transmittal to the Governor and owner should indicate that under the provisions of the Freedom of Information Act, the documents will be subject to release upon request after receipt by the Governor. Proposed final reports will be considered as internal working papers not subject to release under the Freedom of Information Act. Corps personnel, A-E contractor personnel and others working under supervision of the Corps will be cautioned to avoid public statements about the condition of the dam until after the District Engineer has approved the report. The Corps will respond fully to inquiries after the Governor has received the approved report or been notified of an unsafe dam. An information copy of the report should be sent to the District office normally having jurisdiction if other than the District responsible for the inspection.
(iv) Follow-up action. A Federal investment of the magnitude anticipated for this inspection program makes it desirable that a reporting system be established to keep the District Engineer abreast of the implementation of the recommendations in the inspection reports. The letters of transmittal to the Governor and owner will request that the District Engineer be informed of the actions taken on the recommendations in the inspection reports. However, the National Dam Inspection Act only authorizes the initial inspection of certain dams; therefore, once a report is completed no reinspection will be undertaken.
(4) Unsafe dams. The investigating engineer will be required to immediately notify the District Engineer when a dam is assessed as being unsafe. He will also indicate if probable failure of the unsafe dam is judged to be imminent and immediate action is required to reduce or eliminate the threat. The District Engineer will evaluate the findings of the investigating team and will immediately notify the Governor and the owner if the findings are Unsafe Non-Emergency or Unsafe-Emergency. The appropriate State agency and the Corps of Engineers officials having emergency operation responsibility for the area in which the dam is located will also be notified. The information provided in the unsafe dam notice shall be as indicated in Appendix F. Any emergency procedures or remedial actions deemed necessary by the District Engineer will be recommended to the Governor who has the responsibility for any corrective actions. As provided in ER 500-1-1, Corps assistance under Pub. L. 84-99 “Advance Measures,” may be made available to complement the owner's and Governor's action under certain conditions and subject to the approval of the Director of Civil Works. The District Engineer's Emergency Operation Officer will coordinate the advance measures request in accordance with existing procedures. Coordination will be maintained between the District responsible for emergency action under Pub. L. 84-90 and the District responsible for the inspection.
(5) Emergency action plans. An emergency action plan should be available for every dam in the high and significant hazard category. Such plans should outline actions to be taken by the operator to minimize downstream effects of an emergency and should include an effective warning system. If an emergency action plan has not been developed, the inspection report should recommend that the owner develop such an action plan. However, the Corps has no authority to require an emergency action plan.
(k) Progress reports. Progress reports should be submitted monthly by the Division Engineer to WRSC. The reports shall include progress through the last Saturday of the month and should be mailed by the following Monday. The reports shall contain the information and be typewritten in the format shown in Appendix G. Copies of Unsafe Dam Data Sheets will be submitted with the progress report. Copies of the completed inspection report for Dams in the Unsafe-Emergency category will be submitted also. (RCS-DAEN-CWE-19)
(l) Contracts—
(1) Corps of Engineers supervision. Contracts for performing inventory and inspection activities under supervision of the Corps of Engineers shall be Fixed-Price Architect Engineer Contracts for Services. A sample scope of work setting forth requirements is provided in Appendix H. Experience has shown that costs for individual dam inspection have been lower when multiple inspections are included in one contract. Therefore, each A-E contract should include multiple dam inspections where practicable. Corps participation in A-E inspections should be held to a minimum. Corps representatives should participate in only enough A-E inspections to assure the equality of the inspections.
(2) State supervision. Contracts with States for performing inventory and inspection activities under State supervision may be either a Cost-Reimbursement type A-E Contract for Services or a Fixed-Price type contract. The selection of Architect-Engineers by the State should require approval of the Corps of Engineers Contracting Officer. The negotiated price for A-E services under cost-reimbursement type contracts with States will also require approval by the Contracting Officer. Contracts with States should require timely submission of the inspection reports to the District Engineer for review and approval. The contract provisions should also prevent public release of or public comment on the inspection report until the District Engineer has reviewed and approved the report. Corps of Engineers participation in State inspections should be limited to occasional selected inspections to assure the quality of the State program.
(m) Training. As indicated in paragraph (f) of this section, one objective of the inspection program for non-Federal Dams is to prepare the States to provide effective dam safety programs. In many States this will require training of personnel of State agencies in the technical aspects of dam inspections. The Office, Chief of Engineers is studying the need for and content of a comprehensive Corps-sponsored training program in dam inspection technology. Pending the possible adoption of such a comprehensive plan, division and district Engineers are encouraged to take advantage of suitable opportunities to provide needed training in dam safety activities to qualified employees of State agencies and, when appropriate, to employees of architect-engineer firms engaged in the program. The following general considerations should be observed in providing such training:
(1) Priority must be placed on inspection of dams and updating the national dam inventory; hence, diversion of resources to training activities should not deter or delay these principle program functions.
(2) Salaries, per diem and travel expenses relating to training activities of State employees will be a State expense. There will be no tuition charge for State employees.
(3) Architect-Engineer firms will be required to pay expenses and tuition costs for their employees participating in Corps-sponsored training activities.
(4) Corps-sponsored training will require that each trainee is a qualified engineer or geologist and will concentrate on engineering technology related directly to dam safety. (This may require screening of proposed candidates for training.)
(5) Under this program, the Corps will not sponsor training that is intended primarily to satisfy requirements for a degree.
(6) Training by participation in actual dam inspections and/or management of the inspection program should be encouraged.
Table 1—Storms With Rainfall ≥150% of PMP, U.S. East of the 105th Meridian (for 10 mi2, 6 Hours; 200 mi2, 24 Hours and/or 1,000 mi2, 48 Hours)
Storm date Index No. Corps assignment No. (if available) Storm center Latitude Longitude
Town State
July 26, 1819 1 Catskill NY 42°12′ 73°53′
Aug. 5, 1843 2 Concordville PA 39°53′ 75°32′
Sept. 10-13, 1878 3 OR 9-19 Jefferson OH 41°45′ 80°46′
Sept. 20-24, 1882 4 NA 1-3 Paterson NJ 40°55′ 74°10′
June 13-17, 1886 5 LMV 4-27 Alexandria LA 31°19′ 92°33′
June 27-July 11, 1899 6 GM 3-4 Turnersville TX 30°52′ 96°32′
Aug. 24-28, 1903 7 MR 1-10 Woodburn IA 40°57′ 93°35′
Oct. 7-11, 1903 8 GL 4-9 Paterson NJ 40°55′ 74°10′
July 18-23, 1909 9 UMV 1-11B Ironwood MI 46°27′ 90°11′
July 18-23, 1909 10 UMV 1-11A Beaulieu MN 47°21′ 95°48′
July 22-23, 1911 11 Swede Home NB 40°22′ 96°54′
July 19-24, 1912 12 GL 2-29 Merrill WI 45°11′ 89°41′
July 13-17, 1916 13 SA 2-9 Altapass NC 35°33′ 82°01′
Sept. 8-10, 1921 14 GM 4-12 Taylor TX 30°35′ 97°18′
Oct. 4-11, 1924 15 SA 4-20 New Smyrna FL 29°07′ 80°55′
Sept. 17-19, 1926 16 MR 4-24 Boyden IA 43°12′ 96°00′
Mar. 11-16, 1929 17 UMV 2-20 Elba AL 31°25′ 86°04′
June 30-July 2, 1932 18 GM 5-1 State Fish Hatchery TX 30°01′ 99°07′
Sept. 16-17, 1932 19 Ripogenus Dam ME 45°53′ 69°09′
July 22-27, 193 20 LMV 2-26 Logansport LA 31°58′ 94°00′
Apr. 3-4 1934 21 SW 2-11 Cheyenne OK 35°37′ 99°40′
May 30-31, 1935 22 MR 3-28A Cherry Creek CO 39°13′ 104°32′
May 31, 1935 23 GM 5-20 Woodward TX 29°20′ 99°28′
July 6-10, 1935 24 NA 1-27 Hector NY 42°30′ 76°53′
Sept. 2-6, 1935 25 SA 1-26 Easton MD 38°46′ 76°01′
Sept. 14-18, 1936 26 GM 5-7 Broome TX 31°47′ 100°50′
June 19-20, 1939 27 Snyder TX 32°44′ 100°55′
July 4-5, 1939 28 Simpson KY 38°13′ 83°22′
Aug. 19, 1939 29 NA 2-3 Manahawkin NJ 39°42′ 74°16′
June 3-4, 1940 30 MR 4-5 Grant Township NB 42°01′ 96°53′
Aug. 6-9, 1940 31 LMV 4-24 Miller Isl LA 29°45′ 92°10′
Aug. 10-17, 1940 32 SA 5-19A Keysville VA 37°03′ 78°30′
Sept. 1, 1940 33 NA 2-4 Ewan NJ 39°42′ 75°12′
Sept. 2-6, 1940 34 SW 2-18 Hallet OK 36°15′ 96°36′
Aug. 28-31, 1941 35 UMV 1-22 Haywood WI 46°00′ 91°28′
Oct. 17-22, 1941 36 SA 5-6 Trenton FL 29°48′ 82°57′
July 17-18, 1942 37 OR 9-23 Smethport PA 41°50′ 78°25′
Oct. 11-17, 1942 38 SA 1-28A Big Meadows VA 38°31′ 78°26′
May 6-12, 1943 39 SW 2-20 Warner OK 35°29′ 95°18′
May 12-20, 1943 40 SW 2-21 Nr. Mounds OK 35°52′ 96°04′
July 27-29, 1943 41 GM 5-21 Devers TX 30°02′ 94°35′
Aug. 4-5, 1943 42 OR 3-30 Nr. Glenville WV 38°56′ 80°50′
June 10-13, 1944 43 MR 6-15 Nr. Stanton NB 41°52′ 97°03′
Aug. 12-15, 1946 44 MR 7-2A Cole Camp MO 38°40′ 93°13′
Aug. 12-16, 1946 45 MR 7-2B Nr. Collinsville IL 38°40′ 89°59′
Sept. 26-27, 1946 46 GM 5-24 Nr. San Antonio TX 29°20′ 98°29′
June 23-24, 1948 47 Nr. Del Rio TX 29°22′ 100°37′
Sept. 3-7, 1950 48 SA 5-8 Yankeetown FL 29°03′ 82°42′
June 23-28, 1954 49 SW 3-22 Vic Pierce TX 30°22′ 101°23′
Aug. 17-20, 1955 50 NA 2-22A Westfield MA 42°07′ 72°45′
May 15-16, 1957 51 Hennessey OK 36°02′ 97°56′
June 14-15, 1957 52 Nr. E. St. Louis IL 38°37′ 90°24′
June 23-24, 1963 53 David City NB 41°14′ 97°05′
June 13-20, 1965 54 Holly CO 37°43′ 102°23′
June 24, 1966 55 Glenullin ND 47°21′ 101°19′
Aug. 12-13, 1966 56 Nr. Greely NB 41°33′ 98°32′
Sept. 19-24, 1967 57 SW 3-24 Falfurrias TX 27°16′ 98°12′
July 16-17, 1968 58 Waterloo IA 42°30′ 92°19′
July 4-5, 1969 59 Nr. Wooster OH 40°50′ 82°00′
Aug. 19-20, 1969 60 NA 2-3 Nr. Tyro VA 37°49′ 79°00′
June 9, 1972 61 Rapid City SD 44°12′ 103°31′
June 19-23, 1972 62 Zerbe PA 40°37′ 76°31′
July 21-22, 1972 63 Nr. Cushing MN 46°10′ 94°30′
Sept. 10-12, 1972 64 Harlan IA 41°43′ 95°15′
Oct. 10-11, 1973 65 Enid OK 36°25′ 97°52′
Table 2—Storms With Rainfall ≥50% of PMP, U.S. West of Continental Divide (for 10 mi 2 6 Hours or 1,000 mi2 for One Duration Between 6 and 72 Hours)
Storm date Index No. Storm center Latitude Longitude Duration for 1,000 mi2
Town State
Aug. 11, 1890 1 Palmetto NV 37°27′ 117°42′
Aug. 12, 1891 2 Campo CA 32°36′ 116°28′
Aug. 28, 1898 3 Ft. Mohave AZ 35°03′ 114°36′
Oct. 4-6, 1911 4 Gladstone CO 37°53′ 107°39′
Dec. 29, 1913-Jan. 3, 1914 5 CA 39°55′ 121°25′
Feb. 17-22, 1914 6 Colby Ranch CA 34°18′ 118°07′
Feb. 20-25, 1917 7 CA 37°35′ 119°36′
Sept. 13, 1918 8 Red Bluff CA 40°10′ 122°14′
Feb. 26-Mar 4, 1938 9 CA 34°14′ 117°11′
Mar. 30-Apr. 2, 1931 10 ID 46°30′ 114°50′ 24
Feb. 26, 1932 11 Big Four WA 48°05′ 121°30′
Nov. 21, 1933 12 Tatoosh Is WA 48°23′ 124°44′
Jan. 20-25, 1935 13 WA 47°30′ 123°30′ 6
Jan. 20-25, 1935 14 WA 47°00′ 122°00′ 72
Feb. 4-8, 1937 15 Cyamaca Dam CA 33°00′ 116°35′
Dec. 9-12, 1937 16 CA 38°51′ 122°43′
Feb. 27-Mar. 4, 1938 17 AZ 34°57′ 111°44′ 12
Jan. 19-24, 1943 18 CA 37°35′ 119°25′ 18
Jan. 19-24, 1943 19 Hoegee's Camp CA 34°13′ 118°02′
Jan. 30-Feb. 3, 1945 20 CA 37°35′ 119°30′
Dec. 27, 1945 21 Mt. Tamalpias CA 37°54′ 122°34′
Nov. 13-21, 1950 22 CA 36°30′ 118°30′ 24
Aug. 25-30, 1951 23 AZ 34°07′ 112°21′ 72
July 19, 1955 24 Chiatovich Flat CA 37°44′ 118°15′
Aug. 16, 1958 25 Morgan UT 41°03′ 111°38′
Sept. 18, 1959 26 Newton CA 40°22′ 122°12′
June 7-8, 1964 27 Nyack Ck MT 48°30′ 113°38′ 12
Sept. 3-7, 1970 28 UT 37°38′ 109°04′ 6
Sept. 3-7, 1970 29 AZ 33°49′ 110°56′ 6
June 7, 1972 30 Bakersfield CA 35°25′ 119°03′
Dec. 9-12, 1937 31 CA 39°45′ 121°30′ 48
Appendix III to App. D to § 222.6—Pub. L. 92-367
[44 FR 55336, Sept. 26, 1979, as amended at 45 FR 18925, Mar. 24, 1980. Redesignated at 60 FR 19851, Apr. 21, 1995]

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