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sacramento delta
An aerial view of the Sacramento-San Joaquin River Delta near San Francisco Bay.Photo courtesy

Periphery Canal Redux?

Tunnel Revision

••••••• December 20, 2023 •••••••

Glenn Rogers
Glenn Rogers

The Delta Conveyance Project (DCP) is back on the drawing board, attempting to use one tunnel to bypass the Delta and move clean water to the Los Angeles Southern Basin. Initially, there were two tunnels, but more water leaving the Delta was soon realized to be a bad idea. The project is not unlike the Peripheral Canal, which was rejected by a voter referendum in 1982. One main difference between this tunnel and the Peripheral Canal is the DCP tunnel goes straight through sensitive Delta habitat, severely damaging the environment, while the Peripheral Canal skirted the Delta and caused less physical habitat damage.

Sandhill CranesPhoto courtesy


Climate change has caused 20 years of drought in the west, leaving the Colorado River far less water. Lake Powell has dropped as much as 170 feet. What is likely to happen to the Colorado? Water will drop so low that existing locations for water discharge into Lake Mead or Lake Powell will be above the water line.

Lake Powell
Lake PowellPhoto courtesy The Guardian

When this happens, new holes must be drilled through the existing dam to allow water to enter the lake. Besides creating a lack of water for crops and drinking water for cities, the drought also minimizes electricity production.

Then, water temperatures in the Grand Canyon can become a roller coaster ride of frigid night-time temperatures followed by warmer temperatures in the day, throwing the ecosystem into a perilous decline.


No wonder water from the Delta is welcome to the Los Angeles Southern Basin. However, what will happen to the Northern California water supply that is so dear to local farmers, fishermen, and native Americans? ”


Delta Smelt
Delta Smelt

No wonder water from the Delta is welcome to the Los Angeles Southern Basin. However, what will happen to the Northern California water supply that is so dear to local farmers, fishermen, and native Americans? Delta Smelt, considered an indicator species of the health of the Delta, were classified as endangered in 2009. In 2007, there were too few species to count, indicating that this species is near extinction and down to less than 1% of historical numbers.

Researchers believe the Delta Smelt is likely to become extinct within 20 years. Sadly, the Delta Smelt is only one of 12 original species threatened in the Delta. Other species near extinction include the longfin smelt, salmon and sturgeon.


woolly rose mallow
Woolly Rose MallowPhoto courtesy

Today, less than 2% of marsh habitat in the Sacramento-San Joaquin Delta remains. Most notable of these plant species, which occur nowhere e lse, are the Delta tule pea (Lathyrus jepsonii var. jepsonii) and the woolly rose mallow (Hibiscus lasiocarpos var. occidentalis), which are considered seriously threatened due to habitat disturbance and development. The California Native Plant Society testified in hearings for the Peripheral Canal in the 1980s.

Their position was that saltwater intrusion can also cause habitat loss in the Delta as more water is diverted to the Los Angeles Southern Basin.


Salt Ponds in San Francisco Bay
Photo courtesy

A common misconception about freshwater is that it is wasted when it flows into the Pacific Ocean during the winter. Farmers are quick to criticize government agencies that allow this water to be misused since water provides jobs and a source of food for Californians, if not the whole world. This naive view of the ecosystem disregards the fact that the southern part of the San Francisco Bay, which is often very shallow and subject to poor circulation, can only dispose of pollution when surplus freshwater flows into the southern SF Bay during the winter. Without this excess of abundant freshwater, pollutants build up to dangerous levels. This body of water, we should not forget, generates salt used by the whole nation. We should allow this water to be as clean as possible.


Water comes from three sources in the LA Basin. Imported water (from the State Water Project), which will become the Delta Conveyance Project), the Colorado River is also a source of imported water. Other sources of water include surface water and recycled water. Lastly, groundwater is available to the population. Water from the Colorado River is an unreliable source.


Today, water is used to support the environment (10%), agriculture (80%) and the rest is used for drinking water (10%).

Agriculture can significantly improve water-use efficiency with the use of drip irrigation. Currently, farmers are using drip irrigation, consuming the same amount of water they did in the 1960s. We are glad farmers made the change, but they need to do more.

Glenn Rogers, RLA
Landscape Architect / License 3223

December 20, 2023

Glenn Rogers
Glenn Rogers

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