Narrative:

I was level at 1;700 ft and 8 miles north of kttd. I checked in with kttd tower and they instructed me to enter a right base for runway 25. Within 15 seconds; ttd tower called again about traffic just off grove (1w1) at 1;300 feet. I reported that we were looking and mentally this became my number one priority to avoid that traffic. Shortly after; ttd tower reported traffic 1/2 mile; 1;500 feet; northwestbound. I reported no contact with the traffic. I climbed up to a little over 1;800 feet to stay as high as I could without busting pdx class C airspace at 2;000 feet. I also stayed to the right side of lackamas lake to clear the airplane laterally as well. I spotted the plane within 1/4 mile at our 11 o'clock and I estimate he was 300 ft below us although it is hard to say exactly how close he was. He passed underneath us or maybe slightly to the right. By the time I saw the traffic; I had very little time to react; but due to my decision to remain high until I saw the traffic; I was in a position to miss the traffic before acquiring visual contact. Both airplanes were low wings.ttd tower did an excellent job handling the situation by providing quick updates on the traffic even though we were still outside of his airspace. Assessing my performance; I was satisfied with my decision to trust my instinct that I shouldn't descend until I knew for sure where that traffic was. I could have deviated further to the right and possibly used some clearing turns to help identify the traffic sooner. I did use my landing light for identification.this is a very busy corridor with terrain; airspace; and multiple airports. It is a reminder to stay vigilant and plan ahead for traffic avoidance. In the future; I will avoid flying near lackamas lake when traffic is departing to the west.

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Original NASA ASRS Text

Title: A general aviation pilot reported receiving traffic notice by ATC but difficulty in seeing the traffic in a congested area.

Narrative: I was level at 1;700 ft and 8 miles north of KTTD. I checked in with KTTD tower and they instructed me to enter a right base for runway 25. Within 15 seconds; TTD tower called again about traffic just off Grove (1W1) at 1;300 feet. I reported that we were looking and mentally this became my number one priority to avoid that traffic. Shortly after; TTD tower reported traffic 1/2 mile; 1;500 feet; northwestbound. I reported no contact with the traffic. I climbed up to a little over 1;800 feet to stay as high as I could without busting PDX class C airspace at 2;000 feet. I also stayed to the right side of Lackamas Lake to clear the airplane laterally as well. I spotted the plane within 1/4 mile at our 11 o'clock and I estimate he was 300 ft below us although it is hard to say exactly how close he was. He passed underneath us or maybe slightly to the right. By the time I saw the traffic; I had very little time to react; but due to my decision to remain high until I saw the traffic; I was in a position to miss the traffic before acquiring visual contact. Both airplanes were low wings.TTD tower did an excellent job handling the situation by providing quick updates on the traffic even though we were still outside of his airspace. Assessing my performance; I was satisfied with my decision to trust my instinct that I shouldn't descend until I knew for sure where that traffic was. I could have deviated further to the right and possibly used some clearing turns to help identify the traffic sooner. I did use my landing light for identification.This is a very busy corridor with terrain; airspace; and multiple airports. It is a reminder to stay vigilant and plan ahead for traffic avoidance. In the future; I will avoid flying near Lackamas Lake when traffic is departing to the west.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.