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The original item was published from 4/12/2019 12:50:00 PM to 4/12/2019 12:50:39 PM.

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Posted on: April 5, 2019

[ARCHIVED] Share Your Input Regarding Arcata's Hazard Action Plan


The City of Arcata is currently in the process of updating its chapter in the Humboldt Operational Hazard Mitigation Plan and is seeking community feedback.

The Humboldt Operational Hazard Mitigation Plan was developed with guidance from the Humboldt County Office of Emergency Services and Tetra Tech, Inc. and it serves as a key to Humboldt County’s eligibility for funding under FEMA hazard mitigation grant programs. The plan includes an assessment of the area’s risks from hazard events including but not limited to earthquakes, floods, tsunamis, wildfires, and it lists proposed initiatives designed to minimize future hazard-related damage.

Arcata’s Hazard Mitigation Action Plan identifies 18 actions the City will pursue over the next five years in order to minimize Arcata’s hazard risks. In addition, the City has developed a categorized ranking of Arcata’s risk vulnerability to “hazards of interest” identified in the plan, as well as descriptions of other noteworthy vulnerabilities that were not immediately apparent from the risk assessment.

The City is seeking public input regarding its findings and is encouraging members of the community to review the City’s hazard risk-ranking list, noteworthy vulnerabilities and Hazard Mitigation Action Plan. 

The City is seeking feedback on these developments, and Humboldt County and its planning partners are also seeking input from the public on regional hazard mitigation planning! 

The County has designed a questionnaire to help gauge the level of knowledge local residents already have about natural disaster issues and to find out more about areas vulnerable to various types of natural disasters. The information you provide will help our planning partners coordinate activities and identify projects to reduce the risk of injury or damage to property from future hazard events. Please consider taking the County's survey here.

Below you will find Arcata's hazard risk-ranking list, other noteworthy vulnerabilities and Arcata's Hazard Mitigation Action Plan. Please review them, and share your feedback with us. 

If there are any vulnerabilities or hazards you feel we’ve missed, a hazard risk you feel should be ranked differently or if there is an action item you would like to see incorporated into the plan, we want to hear about it!

Please send us an email with your feedback to, or call 707-822-8184.

We will be taking community feedback until the end of the day on Friday, April 19.

Hazard Risk Ranking

Table 1‑11 below presents a ranking of all local hazards of concern for which this Hazard Mitigation Plan provides complete risk assessments. The ranking process involves an assessment of the likelihood of occurrence for each hazard, along with its potential impacts on people, property and the economy. Mitigation actions target hazards with high and medium rankings.

Table 1‑11. Hazard Risk Ranking


Hazard Type






Severe Weather






Sea Level Rise






Dam Failure












Other Noteworthy Vulnerabilities

Mitigation actions target hazards with high and medium rankings.The following Arcata jurisdiction-specific issues have been identified:

  • Water Storage:  The City of Arcata was incorporated in 1858 and has a long history of development, including many wood-framed buildings that do not meet current fire code standards. The City of Arcata has very limited water storage capacity to address the multiple fires that may result from a major earthquake. According to 2017 population estimates, the City of Arcata requires 2.5 MG of Fire Storage based on the American Insurance Association.  This estimate takes into account a population of 18,374 and fire duration of 10 hours. The City meets the fire storage requirements but is lacking emergency storage for users in case of an offline scenario. No official reports have been written on Arcata’s lack of storage, but past experiences have only allowed the system to be offline between a day and a day-and-a-half. Common water storage practices require three times the daily average use for emergency storage.The City would need an additional 2.63 million gallons of storage for fire and emergency storage.

  • Aging Infrastructure: The City’s waterline distribution system and sewer collection system were constructed in the early 1900's and are need in of replacement. These service lines are beyond their useful service life and very susceptible to breaks due to frequent earthquake shocks, as the City is located in the area that is very susceptible to seismic activities.

  • Critical Facilities: The City provides wastewater treatment services at the Arcata Wastewater Treatment Facility (AWTF) for the treatment of residential and commercial sewage that is generated within the City. The AWTF serves approximately 18,695 people, has a design average dry weather flow of 2.3 million gallons per day (MGD), average wet weather flow of 5.0 MGD, and peak wet weather flow of 5.9 MGD. The AWTF is located in Arcata, California, on the northern shoreline of Humboldt Bay, which is a large natural body of water that is connected to the Pacific Ocean. Due to the proximity of the AWTF to Humboldt Bay, flood, earthquake, tsunami, sea level rise and severe storm hazards threaten the facility’s structural and operational integrity. Hazards that threaten the AWTF include the following: the entire AWTF (including its protective levee) is located within the 100-year floodplain and the tsunami inundation zone; the facility is prone to damage due to sea level rise; and it is in active earthquake country (Humboldt Operational Area Hazard Mitigation Plan [HOAHMP], 2014). The rock-armored earthen levee that separates and protects the AWTF from Humboldt Bay surrounds the majority of the outer perimeter of the facility. The top elevation of the levee varies from approximately 10-13 feet NAVD 88, depending on the location. Projections made by the California Coastal Commission (2015) predict that by the year 2050, the Mean Annual Maximum Tide (MAMW) will be 10.7 feet (does not account for storm surges, which would bring the water level even higher), which would overtop and cause subsequent erosion and failure of the existing levee, subsequently flood the AWTF, causing severe damage to equipment and buildings, likely rendering the facility largely inoperable and impacting Humboldt Bay with untreated wastewater. Additionally, the levee does not completely surround the existing facility. The levee protects the AWTF in the locations where it is adjacent to the Bay; however, the northern/northeastern portion of the AWTF is not protected by the existing levee, and elevations in much of this area range from 9 to 11 feet NAVD 88, which is below the floodplain and tsunami inundation zones.

  • Emergency Shelters:  The Arcata Community Center and the D Street Neighborhood Center are the City of Arcata’s two emergency disaster shelters. These centers are set up to supply shelter and amenities in the case of an emergency event. As emergency shelters, the centers need to be able to support community members with various needs. This includes providing food, water, and reliable power. A reliable backup generator at each center will be able to provide power for community members whose medicals needs require electricity. Currently, both locations do not have a reliable backup generator.

Hazard Mitigation Action Plan

Table 1‑13. Hazard Mitigation Action Plan Matrix

Action ARC1— Where appropriate, support retrofitting, purchase or relocate structures located in hazard areas, prioritizing those that have experienced repetitive losses and/or are located in high or medium-risk areas.

Action ARC2— Integrate the hazard mitigation plan into other plans, ordinances and programs that dictate land use decisions in the community, including the Local Coastal Program, the Forest Management Plan, the Arcata Land Use Code and the Arcata General Plan Safety Element.

Action ARC3—Actively participate in plan maintenance protocols outlined in Volume 1 of this hazard mitigation plan.

Action ARC4—Continue to maintain good standing and compliance under the NFIP through implementation of floodplain management programs that, at a minimum, meet the NFIP requirements to:

  • Enforce the flood damage prevention ordinance.
  • Participate in floodplain identification and mapping updates.
  • Provide public assistance/information on floodplain requirements and impacts.

Action ARC5—Identify and pursue strategies to increase adaptive capacity to climate change including but not limited to the following:

  • Conduct a vulnerability assessment for sea level rise;
  • Flood diversion and storage opportunities in wetlands and floodplains;
  • Public outreach and education regarding emergency preparedness and hazard risk awareness.

Action ARC6— Purchase generators for critical facilities and infrastructure that lack adequate backup power, including emergency locations at the Arcata Community Center and D Street Neighborhood Center.

Action ARC7— Implement the City’s Capital Improvement Plan.

Action ARC8— Improve reliability of continued operations of critical water pump station on Alliance Road during emergencies.

Action ARC9— Continue to support the Hazard Mitigation Plan partnership as well as local hazard mitigation working groups.

Action ARC10— Continue to improve levees around risk critical facilities.

Action ARC11— Develop a list of needed seismic retrofits of City’s critical facilities.

Action ARC12— Improve local radio communication on a designated shared channel.

Action ARC13— Develop detailed lists of existing and needed emergency resources (shelters, food sources, etc.).

Action ARC14— Continue to support the development and ongoing training of Community Emergency Response Teams (CERT)

Action ARC15— Maintain updated Hazard and Emergency Preparedness information on the City’s Website with a link to the County’s Website.

Action ARC16— Develop Semi-annual City staff training in community emergency response.

Action ARC17— Increase emergency water storage capacity (fire protection, back-up supply, etc.).

Action ARC18— Develop a Debris Management Plan.

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