Regional drinking water quality monitoring program: long-term monitoring of water quality in select canals, reservoirs, and treatment plants of the greater Phoenix, Arizona metropolitan area drinking water system, ongoing since 1998

Regional Drinking Water Quality Monitoring Program
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Arizona Statue University (ASU) has been working with regional water providers
(Salt River Project (SRP), Central Arizona Project (CAP)) and metropolitan
Phoenix cities since 1998 on algae-related issues affecting drinking water
supplies, treatment, and distribution. The results have improved the
understanding of taste and odor (T&O) occurrence, control, and treatment,
improved the understanding of dissolved organic and algae dynamics, and
initiated a forum to discuss and address regional water quality issues. The
monitoring benefits local Water Treatment Plants (WTPs) by optimizing ongoing
operations (i.e., reducing operating costs), improving the quality of municipal
water for consumers, facilitating long-term water quality planning, and
providing information on potentially future-regulated compounds. ASU has been
monitoring water quality in terminal reservoirs (Lake Pleasant, Saguaro Lake,
and Bartlett Lake) continuously from 1998 to the present for algae-related
constituents (taste and odors, and more recently metals from the upper
reservoirs), nutrients, and disinfection by-product precursors (i.e., total and
dissolved organic carbon and organic nitrogen). Additional monitoring has been
conducted in the SRP and CAP canal systems and in water treatment plants in
Phoenix, Tempe and Peoria. During this work the Valley has been in a prolonged
drought and recently one above average wet year, and this data provides
important baseline data for development of new or expanded WTPs and management
of existing WTPs in the future. The current work has improved the understanding
of T&O sources and treatment, but additional research and monitoring into the
future is necessary.

Reservoir monitoring is conducted once per month at Bartlett Lake, Saguaro
Lake, and Lake Pleasant, and quarterly at Roosevelt, Apache, and Canyon Lakes.
Samples are depth integrated in the epilimnion and hypolimnion. CAP will
collect samples from Lake Pleasant. SRP will collect samples from Bartlett,
Saguaro, Roosevelt, Apache, and Canyon Lakes. Field measurements for
temperature with depth will also be collected. River samples (Salt River below
Saguaro Lake @ Blue Point Bridge and Verde River at the Beeline Highway) will
be collected once per month. Samples will be analyzed for carbon (TOC/DOC),
total nitrogen, total phosphorous, arsenic, conductance and T&O compounds (MIB,
Geosmin, Cyclocitrol). The purpose of the lake sampling is to provide early
warning information on potentially large changes in water quality – due to
algae production, lake destratification, and forest fire or other runoff
events. Additional monthly sampling will be coordinated with USGS (Salt River
above Roosevelt, Verde River at Tangle) and CAP (Lake Havasu).

Canal monitoring is conducted once per month (January through June), and twice
per month as needed during periods of higher T&O production (i.e.,
July-December). Field measurements for temperature and pH will be made.
Sampling will include the CAP, Arizona, and South canals at multiple locations.
Monthly samples will be analyzed for carbon (TOC/DOC), SUVA/UV254, total
dissolved nitrogen, microbes, conductance, and T&O compounds (MIB and Geosmin).
Bi-weekly samples will be analyzed only for T&O compounds. The purpose of the
canal sampling is to identify hot-spots of T&O production and to make
recommendations to the cities/SRP/CAP to perform some type of treatment
(brushing, copper, etc.). Additional canal sampling will be scheduled to
further identify canal hot spots or to provide more frequent process control
information.

WTP raw and finished water is collected once per month (January through June),
and twice per month as needed during periods of higher T&O production (e.g.,
July-December). WTP sampling will be conducted at two Tempe WTPs, one Peoria
WTP, Glendale WTPs and other selected WTPs. Monthly samples will be analyzed
for carbon (TOC/DOC), SUVA/UV254, total dissolved nitrogen, microbes,
conductance, and T&O compounds (MIB and Geosmin). Bi-weekly samples will be
analyzed only for T&O compounds. The purpose of the WTP sampling is to provide
continued evaluation of water quality produced at the WTPs.