will be divided into three distinct parts: (1) pre-logging calibra- 
tion period, (2) transition period, and (3) post-logging period. The 
calibration period will continue as long as a watershed remains uncut. 
Logging began on one of the watersheds, Maybeso Creek, in August, 1953. 
This report presents a summary of the results of research for the 
first 5-year period. 
CLIMATE AND WATERSHEDS OF SOUTHEAST ALASKA 
Climate 
Precipitation is generally heavy in Southeast Alaska and is well 
distributed throughout the growing season. Total annual precipitation 
varies from approximately 20 inches in the extreme northern portion 
to over 150 inches in the southern and southwestern portions (fig. 1). 
The least amount of rainfall occurs during the months of May, June, 
and July, and ranges from 10 to 15 percent of the annual. The largest 
percentage occurs during the months of September, October, and 
November; frequently being 35 percent of the annual. As a general 
observation, at least 50 percent, and sometimes 60 percent, of the 
annual precipitation occurs during the five months of September 
through January (7). Wide departures from these average conditions 
occur, however. Stations with long records show that precipitation 
during the wettest years ranges from 20 to 65 percent above normal 
years, while the driest years may show a range of 10 to 44 percent 
below normal. 
The climate of Southeast Alaska is characterized by mild winters 
and cool summers; a relatively narrow range exists between tempera- 
ture extremes during the year (1). Snowfall is moderate except on 
elevated mountain slopes. Near sea level the first frosts generally 
occur in September or October, and the last in May or early June. 
Average length of growing season, which varies considerably with loca- 
tion, is about 180 days (2). 
Watersheds 
Southeast Alaska is composed of a narrow strip of continental land 
bordered by a large and unbroken chain of mountainous islands. Streams 
of the Alexander Archipelago and of the mainland are typically short 
and empty into salt water. The watersheds, which are generally small, 
have soils with thin, poorly developed mineral horizons, and deep un- 
incorporated organic layers. Many muskegs, consisting of deep, poorly 
decomposed and water-logged organic materials, are found in the drainage 
area. The prevalence of large quantities of organic matter in these 
soils is conducive to high water-holding capacity. The impermeable 
nature of underlying materials, steep slopes, and general shallowness 
of the soils, however, severely limit ground-water storage. In 
addition, soils are often near the saturation point in this region of 
high precipitation. Runoff is generally rapid, except in streams which 
head in lakes, and streams are frequently reduced from maximum to 
minimum flow within a short time after precipitation ceases (ll) (21). 
Figs. 2 and 3 show Indian Creek during high and low stream stages. 
