On Sunday I GPSed the courses of the two largest ditches in Green Valley: the High Ditch (HD), which traverses all of Green Valley, from east to west; and the Green Valley Blue Gravel Mine Ditch (GVBGMD), which begins on the North Fork upstream from Euchre Bar, crosses the river about midway between Euchre Bar and Green Valley, and ends in the center of Green Valley.
I found that the High Ditch holds an elevation of about 2100 feet, or a little less, and the GVBGMD comes in at about 1960 feet, or a little more or less, at its terminus, in the center of Green Valley.
Tom Martin of Alta tells me that the High Ditch is called the McCaffery Ditch, and that it took its water from the North Fork of the North Fork (NFNFAR). He cited Gene Markley as the source for this information. I called Gene and asked him about it. He said that he learned the name from Matt Bailey; and suddenly I understood the origin of that name. It appears on the earliest official map of this area, the 1866 General Land Office map of Township 15 North, Range 11 East (a "township," in the surveying sense, meaning a six-by-six block of thirty-six "sections," each section nominally a square mile--and here in Northern California, the numbering of townships is referenced to Mt. Diablo as the local "origin" of coordinates--that is, we here, near Green Valley, are in the 15th township north of Mt. Diablo, and the 11th township east of Mt. Diablo. The northeast corner of the township is thus 90 miles north, and 66 miles east, of Mt. Diablo. By the Theorem of Pythagoras (combined with the Flat Earth of Ptolemy), that means that Mt. Diablo is about 111 miles from where Casa Loma Road crosses the railroad tracks.)
At any rate. On this 1866 map, along the east boundary, in Green Valley, is a little black square with the words "Mchaffey's House and Garden." It is easy to see how "Mchaffey" could become "McCaffery." This surname is usually spelled 'McHaffey'; let us imagine that the surveyors, in 1866, mistakenly used a small 'h', and correct their error. And, the High Ditch terminates not far from the McHaffey house site, today, marked by much Vinca and some cellar holes and fruit trees. It is close to the Pyramid, in the west part of Green Valley, and right on the West Trail.
However, the High Ditch existed to serve the hydraulic mine(s) at the west end of Green Valley, not McHaffey's garden. Perhaps McHaffey himself was the owner of one or more of the mines there; perhaps he built the ditch, or hired it done; it would have been quite costly. But, I do not know that. For now I reject the "McHaffey" name in favor of the generic and descriptive "High Ditch." Perhaps it could be called the Pyramid Ditch.
But, what of this business about the High Ditch originating on the North Fork of the North Fork? It turns out that Gene Markley himself had made the same mistake I had, in mistaking the High Ditch for the ditch which is cut into the marble cliffs at the east end of Green Valley.
I knew that this marble-cliff ditch is the GVBGMD, but (like Gene) I *had* thought it was the same ditch which crosses all Green Valley to end near the Pyramid--near the McHaffey house site. It is not. The High Ditch originates within Green Valley itself, at the very east end, drawing water from what I call Iron Point Ravine, and probably also taking water from the other ravines along its way west--Casa Loma, Moonshine, and Ginseng ravines (my names). If one scouts past the source of the High Ditch, across Iron Point Ravine to the south and east, there is no trace of any continuation.
But, even the GVBGMD did not originate on the NFNFAR. Instead, it drew from the main North Fork, well above the confluence with the NFNFAR, and crossed the North Fork about .35 mile downstream from the Euchre Bar bridge. Today, only a cable crosses the river at that point. One can easily find and follow the line of the GVBGMD on the south side of the NF at Euchre Bar, either east or west, upstream or down; follow it west and downstream, and it mysteriously ends, near the cable.
Similarly, one can scramble out along the marble cliffs at the east end of Green Valley, and follow the GVBGMD upstream, to where, again, it mysteriously ends, near the cable. I figured out about twenty years ago that it must have crossed the North Fork on a flume, near the cable. And this was confirmed by an 1876 newspaper article from the Dutch Flat Forum, which describes operations of the GVBGM, and the ditch, and the flume.
Let me quote from that article about the GVBGM: first, an inexact reference to the cost of the ditch:
"Ten men are employed who work the claim night and day, and, having a strata of gravel which prospects well, it is thought that it will pay expenses this run. The disbursements of this Co. since active measures were taken to construct a canal, up to the present time, has been between $60,000 and $70,000, while the receipts have been but $1800."
And next, the description of the flume across the North Fork:
"Another important and interesting item which has not been mentioned, is the trestle-work erected on the bridge to convey the water to a corresponding height on the opposite side of the river. The height of the bridge as before mentioned is 62 ft. from the bed of the river, and the trestle-work is 73 ft. up to the bed of the flume, making in all 139 ft. to the top of the flume. The American River at this point on its bed is about 40 ft. wide, and when its rushing waters are at their height and come plunging through this narrow gorge, it forms a scene, when viewed from a central position over the river, which would well repay those who admire the grandeur of nature together with the remarkable achievements of science and art."
It is true that the GVBGM has almost the perfect elevation to be the downstream continuation of the large mining ditch which indubitably does come down the NFNFAR to Euchre Bar. However, I believe that ditch served the minor hydraulic mines at Euchre Bar itself. There is certainly no sign of its continuation downstream, on the south side of the river, west of the Euchre Bar mines. I've been over those steep rubbly slopes twice, searching for it, years ago.
It is also possible, however, that the bridge mentioned in the 1876 article was the Euchre Bar bridge itself. Then the ditch coming down the NFNFAR might have been led across here, from the north side to the south side--only to cross again, .35 mile downstream. I regard this as highly unlikely.
While raising these kinds of points in my conversation with Gene, he eventually conceded that, yes, the ditch cut into the marble cliffs does not go through to Euchre Bar on the south side of the river; he recalled that there was a section one always had to just scramble, along the river itself.
All this just goes to show that it can be hard to figure out the origins and courses of old mining ditches, especially when one, like the GVBGMD, does something really strange--cross the North Fork itself, on a flume the newspaper article declares to be "139 feet" above the river. Suppose the flume was four feet high; then the bottom of the flume would have been 135 feet above the North Fork.
The crossing point is about 3/4 of the distance between where the 1840-foot contour crosses the North Fork, just above the marble cliffs, where Sugarloaf Ravine meets the river, and where the 1880-foot contour crosses. Hence we could take the elevation of the river at the crossing to be 1870 feet. Add 135 feet--and one arrives at 2005 feet for the elevation of the ditch at the crossing.
This is in good accord with my GPSed elevations for the GVBGMD to the west--it came in at 2000 feet at the marble cliffs, and around 1960 to 1980 feet at its terminus. However, I have found that, when near cliffs, GPS data is not to be trusted. Cliffs reflect the satellite signals and wreak havoc on the GPS unit's calculation of position. Trees also cause problems. And then, when one gets home, and hooks the GPS unit up to the computer, and downloads the waypoint and track data to a properly-georeferenced topographic map, using just the right "geoid" or map datum, one often finds that the elevations one recorded on the ground, do not match up well with contour lines on the map. For instance, at the terminus of the GVBGM, in the center of Green Valley, I was getting consistent readings of about 1985 feet; but, plotted on the map, the terminus came in below the 1960-foot contour.
I believe there is a goodly amount of inaccuracy in topographic maps, in the positions of the contour lines. The Dutch Flat quadrangle's rendering of the trails in Green Valley is simply terrible. Combine the built-in inaccuracies of the map with the inevitable inaccuracies of GPS and one is left having to make rather arbitrary decisions. For instance, in a best-possible drawing of the High Ditch on the Dutch Flat quadrangle, one might simply choose to use an elevation of 2100 feet, which is half-way between the 2080- and 2120-foot contours. A refinement might be to give the line of the ditch a gentle grade, of perhaps 10 to 20 feet per mile, from east to west.
Aerial photos would help resolve these kinds of mapping problems.
I can send a fairly large (~300K) map showing my GPS track records for the two ditches, and a photograph (~80K) of the GVBGM crossing the marble cliffs, to anyone interested.
The next-largest ditch in Green Valley is on the south side of the river, at about 2200' elevation; it drew from Giant Gap Ravine and McIntyre Ravine and delivered water to the Hayden Hill Mine. I have not GPSed this ditch, yet, but I have hiked it.
There are many many smaller ditches in Green Valley.