Collins, B., 1998. Preliminary Assessment of Historic Conditions of the Skagit River in the Fir Island Area – Implications for Salmonid Habitat Restoration. Skagit System Cooperative, La Conner, WA. pp. 72.

This investigation describes current and historic conditions of distributary and blind-tidal channels of the
lower Skagit River, downstream from where it branches into the North and South forks and forms Fir Island
before entering Skagit Bay. The study is pan of a larger effort by the Skagit System Coop to document
salmonid habitat use and estimate historic habitat loss and its potential for future restoration.
Fir Island is a relatively small portion of the river’s historic delta. Prior to late-19th century river diking,
floodwaters and associated suspended sediment commonly exited to Samish Bay and Padilla Bay as well as
to Skagit Bay. According to several map sources, historically at least one-half of the delta was perennially
wet, consisting of tidal marsh, fresh-water marsh, or open channels. A persistent logjam nearly a mile long
at the town of Mount Vernon presented an obstruction to floodwaters, and contributed to the routing of
floodwaters onto the Skagit Flats and to Padilla and Samish bays. Removal of the jam in the late 1870s and
the later completion of an effective diking system together increased the efficiency with which floodwater
was routed to the Fir Island area. This enhanced routing of floodwater to Fir Island was later counterbalanced
beginning in the 1930s by headwaters dams which substantially reduced flood peaks.
The river historically stored and transported vast amounts of large woody debris. Records of the federal
“snagging” program provide an indication of the amounts of debris that accumulated in the river. For example,
35,000 snags were removed from the lower Skagit River in the two decades prior to 1910. Snags
included very large pieces: the snag-boat captain’s records include the largest-diameter snag removed each
year from Puget Sound rivers. The maximum diameter ranged between 3.7 m and 5.2 m in the 1898-1909
period. It is likely that such large snags had significant geomorphic effects such as retaining and sorting
sediment and scouring pools. The very large number of pieces would also have significantly affected
stream productivity and the organic matter budget. Debris transported in floods also tended to plug distributary
channels, especially in the South Fork. By the turn of the century, streamside forests were logged