1904 - The first recorded mosquito control efforts in California were under the direction of UC Professors and were directed at the
salt-marsh mosquitoes in the San Francisco Bay marshlands.

1908 - Malaria was devastating the central valley.

1910 - The first anti-Malaria program was started in the Sacramento Valley at Penryn.

1915 California Legislature adopted the 'Mosquito Abatement Act' which formed the basis for the formation, governing powers, and
functions of mosquito abatement and vector control districts.


1922 DELTA MOSQUITO ABATEMENT DISTRICT was formed with 16 sq miles including all of
the city of Visalia plus some adjacent suburban area. Malaria was a common
disease at that time, and pest mosquitoes provided an added stimulus
for the residents to attempt control.
The Visalia Women's club played a key part in our formation.

The Board held meetings downtown at a bank, and Percy Menefee was the
first Superintendent. Hired at the rate of $150/month.

1928 The total budget for the District was set at $1900 dollars.

April 1933 the adjacent area North and West of our boundaries were added because we needed to control producers that were
sending mosquitoes into the populated areas of the city.

1937 the District's budget was increased by $500 to include a new car.

1942 US Military requested the District's help in reducing mosquito numbers at the Visalia Airport, which they were using for
military purposes

1946, October: The area from Goshen to the Woodlake hills was annexed to the District.

Delta MAD and Tulare MAD jointly hired an entomologist that they shared for several years.

Land was purchased on Houston Avenue for $600.00

1947, February: The areas North and West of the then current District was annexed to the County line, with the border northeast
following a school district boundary

1947, November Exeter, Farmersville and Three Rivers areas were annexed into the District.

1947, November: The Three Rivers area was removed from the annexation by board member vote.

Aerial spraying was conducted by contracting with private agencies

1948 purchased used TD-9 tractor for land work

1957, July approximately 2 1/2 miles were added to the district

1958, Annexed this area

1959 Airplane was purchased for aerial spraying

1960, The proposal to provide residents in the City of Lindsay coverage was forwarded and later dropped due to a lack of support.

1973, March 14th: The District changed it's name from 'Delta Mosquito Abatement District' to 'Delta Vector Control District' to reflect
the program, which included the control of mosquitoes, flies and other vectors.

In 1976 it was proposed to annex an area West of Hiway 99 which would include the Visalia Wastewater treatment plant, and an
area south along Mooney Blvd to include Mooney's Grove. This was turned down by LAFCO.

1999 West Nile virus appeared in New York

2002 was the first California Human West Nile virus case

2007 brought our first Aerial reconnaissance flights looking for neglected swimming pools, which had become a huge problem
source, due to high numbers of home foreclosures. The first flights consisted of a man holding the camera out a helicopter window
and taking pictures of some areas that had high numbers of mosquitoes trapped.

2008 commercially available Foreclosed property lists were used to identify potentially empty properties with swimming pools

2008 There was an effort to have the Lindsay-Porterville and even the Springville areas included within adjacent District boundaries.
The Tulare County LAFCO rendered a decision stating that the Tulare MAD is better positioned to take care of the Lindsay-Porterville
area.  The DVCD Board of Directors decided not to pursue the matter in light of economic and geographic circumstances.

The last district Boundary change left the District with approximately 712 Sq miles.
We serve a population of 190,000, including 58,000 households, the incorporated cities
of Visalia, Exeter, Farmersville, Dinuba and Woodlake.

A CDC Report set the totals of WNvirus confirmed and probable infections through the
2008 year as being 28,961 human cases.
11,822 of these infections became Neuroinvasive and had resulted in 1120 deaths.

2009 brought high-tech aerial imaging to Delta.  Contracted agencies, armed with expensive, computer controlled cameras and
sensitive GPS devices, took hi-resolution images of most urban areas. The images were compared to our in-house database of
tracked sources and technicians were dispatched to any newly found green pools.

The City of Visalia Code Enforcement office started draining some problem pools and citing property owners.

By the end of 2009 it is estimated (by the CDC), that more than 1,000,000 birds have been killed by WNv.
There have been 2,867 human WNv cases in California, with 95 deaths

February 2010,  approx. 54,000 Benefit Assessment ballots
were mailed to property owners within The District,
to determine the level of desire  for a local Lab facility.

June 2010,  the number of swimming pools, both in-ground
and above ground, that we have treated is 1379.

The Benefit Assessment passed.

July of 2011 construction began on the new Lab facility

        November 2011 the 'shell' is nearly complete

December 2016, the laboratory received it's Name  "Lourenco Laboratory",
after the retiring Biologist/Assistant Manager.