Parts of Glenn County are sinking at a statistically significant rate. That’s according to a recent study conducted by the state Department of Water Resources.
The survey identifies two areas of concern, one south of Orland, the other South of Hamilton City. The rate of subsidence in Glenn County is orders of magnitude less than in parts of the San Joaquin Valley, but may still create expansive and expensive problems.
The new survey mostly confirms earlier findings.
The findings, show that an area south of Orland sank three and a quarter inches over the last nine years. The area south of Hamilton City sank one and a third inches over the same period. The amounts are less than previously thought. A survey released in January showed the same areas sinking over five inches and by nearly two inches respectively.
When land sinks or subsides, it does so at different rates across an area. That can wreak havoc on rigid objects like bridges, roads and pipelines. It can also disrupt California’s network of gravity dependent canals.
The pumping of large amounts of water from deep pockets below the surface can cause the land above to sink.
The problem is much worse in the San Joaquin Valley where some pockets are sinking by as much as two inches a month. According to a report released this week by NASA, an area near Arbuckle in the Sacramento Valley sank at a rate of an inch per month last year.
DWR Subsidence Study Glenn County