Halleck had arrived in California in 1847 as a lieutenant in the United States Engineers, accompanied by his friend, Lt. William Tecumseh Sherman.

[7] Originating on Big Rock Ridge west of the city of Novato, Nicasio Creek descends initially to the south.

By blockage and inundation the dam reduced by 50 percent of the salmon and steelhead populations entering Lagunitas Creek watershed.

Author and landscape artist Russell Chatham wrote, "One of the most tragic sights I ever beheld was the year after Nicasio Dam blocked that critical watershed.

[9] A river otter (Lontra canadensis) was collected by the Museum of Vertebrate Zoology at the southwest corner of Nicasio Reservoir in January, 2008.

Point Reyes-Petaluma Road crosses the creek in two places: once 3.47 miles (5.58 km) east of State Route 1 on a 133-foot (41 m) concrete continuous tee beam constructed in 1960, and again 3.2 miles (5.1 km) east of State Route 1 on a 102-foot (31 m) concrete tee beam built in 1937.