The Town of Mendocino was established in 1851.
For the first 120 years, the Community did not have a public wastewater
collection system, and to this day does not have a public water system.
Wastewater facilities consisted of cesspools, septic tanks, and some small
private collectors, which discharged untreated wastes over the bluff directly
to the ocean. The residents' water source is still from private wells.
On January 19, 1971, Mendocino City Community Services
District was formed as a first step in solving the community's wastewater
and water problems. Since Mendocino had limited financial resources,
the wastewater treatment plant was given first priority. Public hearings
were held, news articles were published, a citizens committee was formed,
and poster and essay contests were conducted by elementary and high school
students to accurately inform the residents of the important environmental,
esthetic, technical, and financial aspects of the project. Through
the efforts of citizens, business owners, students, and the original MCCSD
Board of Directors the general obligation bonds for the treatment facility
were approved by an 86% "yes" vote. The treatment plant and the collection
system went online in 1975, only four years after the District was formed.
Activated Sludge Wastewater Treatment
MCCSD treats approximately 35 million gallons
of wastewater per year. The plant has the capacity to treat up to
300,000 gallon of water a day.
The District operates an extended aeration activated
sludge treatment plant. The activated sludge wastewater treatment
process is a biological process that uses microorganisms to decompose wastes.
The microorganisms feed and grow on waste particles in the wastewater.
As the organisms grow and reproduce, more and more waste is removed from
the wastewater, leaving the water partially cleaned.
The organisms feed on the wastewater in the aeration
tank (see diagram). After the aeration period, the wastewater is
routed into a settling tank or clarifier. The organisms are allowed
to settle to the bottom of the clarifier, and the treated water, called
effluent, is chlorinated and discharged from the plant. The organisms
that have settled to the bottom of the clarifier are returned to the aeration
tank, so they can feed on the new incoming wastewater.
Severe water shortages continue to exist in Mendocino
during the dry summer months for residents with marginal wells. In
the past twenty-five years, two droughts have affected Mendocino residents,
the first from 1976 to 1977 and the last dry period lasted from 1986 to
In 1990, the MCCSD took over groundwater management
authority from Mendocino County. The District has developed a groundwater
withdrawal program, which limits groundwater extraction. The primary
tool of the Groundwater Management Plan (GMP) is the Groundwater Extraction
Permit Ordinance. The Ordinance is used to establish groundwater
allotments, which are based on the size and type of development on a parcel.
A hydrological study must be performed prior to issuance of a groundwater
extraction permit for new development, to insure that there is adequate
water for the development and that the proposed extraction will not adversely
affect neighboring wells.
The GMP allows local government to mandate the amount
of naturally occurring groundwater that can be withdrawn from the Town's
aquifers on a sustained basis. The purpose of the program is to prevent
depletion of the Town's groundwater by not exceeding the aquifers safe
yield, which is the amount of water that can be pumped regularly and permanently
without dangerous depletion of the groundwater storage reserve.
The District's current groundwater management policies
are to promote water conservation measures, to increase the use of reclaimed
water to reduce groundwater extraction, and to collect and analyze information
on groundwater conditions within the District boundaries to assist the
Board in the groundwater management decision-making process.
Water Reclamation Program
MCCSD has had a recycled water program since 1977.
A new reused water system was constructed at the treatment plant in 1997.
This system pumps tertiary treated effluent from the wastewater plant to
the Mendocino High School. This water is used to irrigate the school
athletic fields. An average of 2 million gallons per year is transferred
to the school. The fields are now in excellent condition, in part
due to the reused water, and the reused water has helped reduce the demand
on the groundwater resource.