The Marion R. Walker Filtration Plant and our aeration/oxygenation systems are responsible for treating water before it reaches our customers. All Casitas customers receive treated surface water from Lake Casitas at some point during any given year and the water may be blended with treated groundwater from our Mira Monte Well. Ojai Water System customers primarily receive treated groundwater from the San Antonio and Mutual well fields. This is typically supplemented by treated surface water during periods of warm weather and drought, when well production is low and demand is high.

Aeration and oxygenation of Lake Casitas is an important first step in providing pleasant tasting and smelling water by supporting aerobic respiration, and inhibiting nutrient cycling and therefore algae growth. This is particularly important during summer months when algae growth is at its highest. The aeration system releases pumped air at a single elevation, while the oxygenation system diffuses pure oxygen at three distinct depths. The rate and depth of oxygen diffusion is optimized by profiling (measuring dissolved oxygen, temperature, and other water quality parameters throughout the water column) and inputting the data into an oxygen plume model. Oxygenating the deep portions of the lake prevents the release of hydrogen sulfide, phosphorous and other undesirable compounds and nutrients from sediments. When algae levels need to be further reduced, low doses of copper sulfate are used along the shoreline. This chemical is distributed at least 100 feet off the shoreline and away from the bass breeding areas at the north end of the lake in an effort to protect bass fisheries.

Water is released from the lake into the filtration plant through a multi-level, screened intake structure. This allows staff to select the depth water is released at 24 foot intervals. Due to ever-changing lake dynamics, we perform regular water quality profiles and test samples taken from depths corresponding with each available intake gate to select the best available raw, untreated water.

The Marion R. Walker Filtration Plant is a high-rate in-line pressure filtration plant. Features include horizontal pressure filters, continuous real-time monitoring and alarm systems. Chlorine is applied for initial disinfection, and converted to chloramines to provide a protective disinfection residual throughout the distribution system. The filter plant clarifies and reduces turbidity in the water. Silt and other natural materials removed from the water are placed in drying beds and later hauled off for disposal. The filtration plant has a pilot plant attached, which is a small-scale treatment plant that simulates the full-scale treatment plant. It is used to evaluate variations in water quality, and allows testing of different treatment options prior to full scale implementation.

The San Antonio Manganese Filtration Treatment Plant filters groundwater from six groundwater wells located within the San Antonio and Mutual well fields. Chlorine is added to aid in filtration and provide a protective disinfection residual in the distribution system.

Casitas service areas include Ojai, Upper Ojai, The Ventura River Valley, City of Ventura to Mills Road and beach areas from Solimar to Rincon and up to the Santa Barbara County Line.

Casitas has a network of pipelines that carry and pump treated water from the Marion Walker Pressure Filtration Plant and San Antonio Manganese Filtration Plant to several above ground reservoirs for temporary storage and eventually our customers. Each reservoir has a mixing device to circulate the water to keep it fresh.

In addition, Casitas has a cross connection control (backflow) program to eliminate the accidental mixing of our water supply with another water source.

Casitas goes above and beyond what is required by state and federal regulations for water quality.

The District monitors the lake, watershed, treatment plants, and distribution systems beyond compliance standards to bring you a consistently safe and dependable water supply.

Casitas regularly tests source water for algae, pH, temperature, turbidity (suspended material), conductivity, dissolved oxygen, and contaminants such as nitrate and heavy metals. The distribution systems are tested weekly for bacterial contamination along with pH, temperature, turbidity, conductivity, and chlorine residual. Other contaminants and parameters are tested for on a monthly, quarterly, or annual basis. The District began its monitoring program for microbiological samples in the 1960s and analyzes supplemental bacteria samples beyond what is required. This supplemental sampling program provides additional assurance customers in all parts of the distribution system are receiving high quality water. Casitas also tests for Giardia and Cryptosporidum, two microscopic protozoan parasites that can cause intestinal distress. The Marion Walker Pressure Filtration system is designed to filter out and inactivate these parasites.

The following items are related to the appearance of the water, and are not health issues.

1. If your water appears discolored and you have galvanized plumbing, let your tap run for a while to clear it up. Galvanized plumbing materials can leach rust into the water if it sits for a long time.
2. Sometimes customers experience discolored water from their hot water heater. To help prevent this drain and flush the hot water heater once a year.
3. When you fill a glass of water at your sink, do you smell a sulfur odor? Sometimes this odor is coming from your sink drain and not your water. Correct this problem by pouring a small amount of bleach into the drain as necessary.
4. If you experience other taste, color, or odor problems that does not clear up after flushing your plumbing lines, you may contact Casitas’ Water Quality Department at 805-649-2251 Ext. 120. Thank you!